Conditions: Cystic Fibrosis Prediabetes
Keywords: cystic fibrosis diabetes inflammation oxidative stress redox balance lung disease
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 33
Healthy volunteers: no

Brief summary:
Acute systemic hyperglycemia causes oxidative stress and a pro-inflammatory response. The pro-inflammatory cytokines induced by hyperglycemia are toxic to islet insulin producing cells, and thus worsen glucose intolerance. Patients with cystic fibrosis (CF) have a high prevalence of CF related diabetes (CFRD) and up to 40% of CF adults develop CFRD. During the prediabetic phase in CF, there is progression from normal glucose homeostasis to high risk prediabetes characterized by episodes of acute hyperglycemia after meals and during respiratory exacerbations. The mild hyperglycemia seen in CF patients with high risk prediabetes following a meal would be expected to induce a degree of systemic inflammation and oxidative stress. These repetitive episodes, if left unchecked, could lead to progression of glucose impairment, worsening severity of oxidative stress and inflammation, and ultimately the development of CFRD, all via hyperglycemia-induced toxicity to beta cells. Furthermore, this process may be accelerated in CF because lung disease and resultant respiratory exacerbations are associated with oxidative stress and inflammation and this will further contribute to beta cell damage.

Sitagliptin is a recently approved agent for type 2 diabetes and markedly enhances insulin secretion in the presence of hyperglycemia and has been shown to be effective in preventing postprandial hyperglycemia. The hypothesis to be tested in this project is that sitagliptin will prevent the development of CFRD in CF subjects with high risk prediabetes by blocking postprandial hyperglycemia. The investigators propose a randomized, double-blind, placebo-controlled, multicenter, 15-month longitudinal study in 118 CF subjects with high risk prediabetes to test this hypothesis. Specifically, the investigators aim to show that chronic treatment with sitagliptin: prevents the conversion to diabetes; results in preservation of beta cell function; reduces systemic measures of oxidative stress and inflammation; and slows the rate of progression of lung disease.

Funding Source - FDA Office of Orphan Products Development

Detailed description:
This was a double-blind, placebo-controlled, multicenter study intending to enroll 118 CF subjects aged 13 years of age or older who have high risk prediabetes. High risk prediabetes was defined during the screening visit by performing an oral glucose tolerance test (OGTT) and finding that the fasting plasma glucose level is between 110-125 mg/dl and/or the 2-hour plasma glucose level is between 140 and 199 mg/dl. Upon enrollment, subjects were randomized to receive either sitagliptin or placebo. Each subject was to be followed for 15 months to determine if sitagliptin prevented the conversion to frank diabetes.

The following was to be done at enrollment and every 6 months: an OGTT with collection of blood at 0, 1/2, and 2 hours for measurement of glucose and insulin in order to determine progression of glucose intolerance; collection of blood at time 0 and 2 hours during the OGTT and measurement of systemic redox status, oxidative stress, and degree of inflammation to determine the degree of basal oxidative stress and inflammation as well as the degree of hyperglycemia-induced oxidative stress and inflammation; collection of exhaled breath condensate in a subset of subjects at selected sites at time 0 and 2 hours during the OGTT and measurement of airway redox status, degree of inflammation, and glucose levels to determine basal respiratory tract redox status and inflammation, the degree of hyperglycemia-induced changes in redox status and inflammation, and correlation between plasma and airway glucose levels; collection of blood to determine safety of the study medication (liver and renal function, complete blood count, electrolyte concentrations); and determination of progression of lung disease as defined by the number of respiratory exacerbations severe enough to require hospitalization and the rate of decline in lung function.

The results of two OGTTs performed at least one week apart was used to determine whether the subject had converted from high risk prediabetes to frank diabetes (primary objective). Conversion to CFRD was defined when both OGTTs were abnormal (abnormal is defined as a fasting plasma glucose level greater than 125 mg/dl and/or a 2 hour glucose level greater than 199 mg/dl). The results of measures of redox balance, oxidant stress and inflammation (secondary objectives) would provide biologic plausibility to our concept on the mechanism of action of sitagliptin in preventing the development of CF diabetes.

Hemoglobin-specific A1c fraction (HbA1c) was to be measured half-way between the 6-monthly visits and a rise of more than 0.5% from the enrollment value would result in two OGTT tests done at least one week apart to determine if diabetes has developed. At these interval study visits, blood was also collected to assess the safety of the study drug and, if the subject was female, to determine if pregnancy had occurred.

In the event that diabetes did develop, the study drug (or placebo) was to be stopped and the subject would have completed the study.

In summary, this was a double-blind, placebo-controlled clinical trial to determine whether sitagliptin prevents the conversion of CF subjects with high-risk prediabetes to frank diabetes. If successful, this would be the first treatment modality available to prevent the development of CFRD, a serious and life shortening complication of CF. Unfortunately, the study sites were unable to achieve enrollment targets and the study was prematurely terminated March 31, 2017 because of low enrollment. For those subjects enrolled in the study, there was no safety concerns. Data are currently being analyzed for the subjects that were enrolled.

Arms:
arm 1: CF patients receiving Sitagliptin.

Intervention: Dose is 100 mg taken orally once a day in the morning with breakfast. Duration is one year or until converted to CF diabetes, whichever comes sooner. arm 2: CF patients receiving placebo.

Intervention: Placebo is taken orally once a day in the morning with breakfast. Duration is one year or until converted to CF diabetes, whichever comes sooner.

Interventions: intervention 1: Sitagliptin
Intervention descriptions: intervention 1: 100 mg of sitagliptin is taken orally each morning with breakfast. Duration is 12 months or conversion to CF diabetes, whichever comes first.

Protocol document:
Prot_SAP_000.pdf: 
 
 
 
 
A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY 
TO DETERMINE WHETHER CHRONIC TREATMENT  
OF CYSTIC FIBROSIS SUBJECTS WITH IMPAIRED GLUCOSE TOLERANCE 
USING SITAGLIPTIN (JANUVIATM) 
PREVENTS THE DEVELOPMENT OF DIABETES 
 
Protocol version date: February 1, 2017 
 
NCT00967798 
 


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A RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED STUDY 
TO DETERMINE WHETHER CHRONIC TREATMENT  
OF CYSTIC FIBROSIS SUBJECTS WITH IMPAIRED GLUCOSE TOLERANCE 
USING SITAGLIPTIN (JANUVIATM) 
PREVENTS THE DEVELOPMENT OF DIABETES 
 
February 1, 2017 
Amendment 36 
 
Principal Investigator 
 
Arlene Stecenko, MD 
Associate Professor of Pediatrics and Medicine 
Emory University School of Medicine 
Atlanta, Georgia 
 
Co-Principal Investigator 
 
Lawrence Phillips, MD 
Professor of Medicine 
Emory University School of Medicine 
Atlanta, Georgia 
 
Other Sites 
Ruth Grossmann, PhD 
University of Iowa 
Iowa City, Iowa 
 
Kevin Kirchner, MD 
Children’s Healthcare of Atlanta at Scottish Rite 
Atlanta, Georgia 
 
Remi Rabasa-Lhoret, MD 
Institut de Recherches Cliniques de Montreal 
Montreal, Quebec, Canada 
 
 
 
 
US IND Number: 101, 313                                                         Compound: Sitagliptin Phosphate 
 
Industry Partner: Merck and Co., Inc.                                                                   Phase: Phase 3 
 
 
 


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INVESTIGATOR AGREEMENT 
 
Protocol Version:  1Feb 2017 
 
 
 
The signature below constitutes the review and approval of this protocol and provides the 
necessary assurances that this trial will be conducted according to all stipulations of the protocol, 
including all statements regarding confidentiality, and according to local legal and regulatory 
requirements and applicable US federal regulations and ICH guidelines. 
 
 
 
 
 
 
 
_________________________________      
_______________________ 
Investigator Signature: 
 
 
 
Date: 
 
*The protocol agreement should be signed by the site Investigator or Co-Investigator who is responsible for the day to day study implementation at 
his/her specific site. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


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 ABBREVIATIONS 
 
 
CF 
 
cystic fibrosis 
  
 
CFRD  
cystic fibrosis related diabetes 
 
 
CRF  
case report form 
 
 
DM 
 
diabetes mellitus 
 
 
DSMB  
Data Safety Monitoring Board 
 
 
DPP 4  
dipeptidyl peptidase IV 
 
 
EBC  
exhaled breath condensate 
 
 
FEV1.0 
forced expired volume in one second 
 
 
GIP 
 
gastric insulinotropic polypeptide 
 
 
GLP-1  
glucagon-like peptide-1 
 
 
HbA1c 
hemoglobin-specific A1c fraction 
 
 
IRB 
 
Institutional Review Board 
 
 
OGTT  
oral glucose tolerance test 
 
 
 


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1. 
OVERVIEW 
 
Hypotheses  
 
 Sitagliptin (JanuviaTM) will prevent the development of diabetes in cystic fibrosis (CF) 
subjects at high risk of developing diabetes. 
 A key pathogenic factor in the development of CFRD is hyperglycemia-induced 
oxidative stress and inflammation. 
 A key factor contributing to worsening lung function in CFRD is airway hyperglycosis 
which induces oxidative stress and inflammation. 
 
Rationale  
 
 
Patients with CF have a high prevalence of CF related diabetes (CFRD).  Patients with 
CFRD have a significantly higher mortality, up to 6-fold higher, than CF patients without diabetes 
(1). Death in CFRD is due to accelerated progression of lung disease and respiratory failure, not 
diabetes-induced vascular disease (2). The pre-diabetic phase in CF patients can last from 2 to 6 
years and is not without deleterious clinical consequences. During this phase there is progression 
from normal glucose homeostasis to high risk prediabetes characterized by episodes of acute 
hyperglycemia after meals and during respiratory exacerbations. CF patients experience 
accelerated decline in lung function and more frequent respiratory exacerbations during the pre-
diabetic phase (3, 4). Retrospective studies suggest that inflammation and oxidative stress are key 
factors contributing to this rapid decline in lung health during the pre-diabetic phase (2, 4). 
 
 
Acute hyperglycemia has been shown to cause oxidative stress and release of inflammatory 
mediators in normal subjects, non-CF subjects with mild prediabetes, and patients with type 2 
diabetes mellitus (DM) (5-7).  This occurs rapidly, within 1 hour of glucose or caloric challenge, and 
can persist for up to 4 hours in subjects with high risk prediabetes or type 2 DM. The mild 
hyperglycemia seen in CF patients with high risk prediabetes following a meal would be expected 
to induce a degree of systemic inflammation and oxidative stress. Oxidative stress and 
inflammation are toxic to the insulin-producing beta cells (9, 10). These repetitive episodes of 
acute postprandial hyperglycemia in CF patients, if left unchecked, could lead to progression of 
glucose impairment, worsening severity of postprandial hyperglycemia, worsening severity of 
oxidative stress and inflammation, and ultimately the development of CFRD, all via hyperglycemia-
induced toxicity to beta cells.  
 
 
We believe that preventing the acute episodes of hyperglycemia in CF subjects would 
prevent the development of CFRD. These episodes of acute hyperglycemia in CF subjects with 
high risk prediabetes are usually mild (ranging from 140 to 200 mg/dl); most frequently follow large 
meals, and often last only a few hours. Therefore standard beta cell enhancers (sulfonylureas, 
glitinides, etc.) are not appropriate for treatment of these episodes of hyperglycemia because of 
their risk of hypoglycemia. Similarly, agents that reduce insulin resistance are not appropriate 
because of their risk of gastrointestinal side effects (metformin) as CF patients already have 
significant gastrointestinal pathology and their risk of edema (thiazolidinediones) as CF patients 
may have hypoalbuminemia. In addition, insulin resistance is not the primary pathophysiologic 
defect in CFRD (11). Since CF subjects with high risk prediabetes still have significant residual 
beta cell mass, agents that prevent hyperglycemia by improving beta cell function could be the 
most effective and safest drugs to treat prediabetes. Sitagliptin is a recently approved agent for 


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type 2 DM. This new drug might be an ideal agent for CF patients with high risk prediabetes as 
sitagliptin markedly enhances insulin secretion in the presence of hyperglycemia by preventing the 
degradation of the incretins, glucagon-like peptide-1 (GLP-1) and gastric insulinotropic polypeptide 
(GIP) (12). 
 
 
 
2. 
BACKGROUND 
 
 
CF – An Overview:  CF is the most common fatal inherited disease of Caucasians and 
affects about 30,000 people in the US (14).  Over 90% of the morbidity and mortality is due to 
progressive pulmonary disease (15). The pathophysiology of CF lung disease consists of the triad 
of decreased mucociliary clearance because of decreased airway surface liquid volume and 
dehydrated mucus; persistent airway infection with bacteria, particularly Pseudomonas aeruginosa 
and Staphylococcal aureus; and an exaggerated inflammatory response. The ultimate outcome is 
destruction of the normal airway architecture and death due to respiratory failure. With therapy, 
primarily aimed at slowing the progression of lung disease and improving nutrition, median survival 
is approaching 40 years of age (14). However, there is no cure for CF. The average CF adult can 
expect to spend 2 to 3 hours a day taking a variety of inhaled medications, have health care costs 
of over $30,000 per year for outpatient medications alone, ingest 30 to 50 pills per day, and be 
hospitalized about once a year for a period of one to three weeks (16). The burden of this illness is 
much heavier if the CF patient develops CFRD.  
 
 
Burden of CFRD: Since it was first described more than 50 years ago, the prevalence of 
CFRD has increased significantly. The primary defect in CFRD is decreased and delayed insulin 
secretion because of beta cell failure (11). Age-specific mortality with CFRD is significantly 
increased compared to mortality in CF patients without diabetes.  CF Foundation Registry data 
published in the 1980’s indicated a six-fold increase in mortality in CFRD compared to CF without 
diabetes (1). More recent data indicate that this excess mortality is most pronounced in females 
(2). Premature death in CFRD is due to rapid progression of lung disease leading to respiratory 
failure and is not due to cardiovascular complications (2). Morbidity in patients with CFRD is also 
significantly higher than in CF patients without diabetes. Patients with CFRD have significantly 
poorer lung function, more frequent respiratory exacerbations, more frequent hospitalization, and 
poorer nutritional status compared to CF patients without diabetes (11).  
 
 
Clinical Impact of the Pre-Diabetes Phase: As with CFRD, the prediabetes phase (which 
can last from 2 to 6 years) is associated with a significant decline in lung health. The rate of decline 
in lung function is proportionate to the degree of glucose intolerance and insulin deficiency (3, 4, 
17, 18). The cause of this excess rate of decline in lung function in CF with high risk prediabetes is 
multifactorial, but the final common pathway might be oxidant injury. Hyperglycemia appears to 
play an important role in the deterioration in lung function as shown by studies in CFRD which 
demonstrated improvement in lung function after glucose levels were improved with the use of 
insulin (4, 17, 18). 
 
 
Hyperglycemia Induces Oxidative stress and Inflammation:  One of the clinical 
characteristics of CF subjects with high risk prediabetes or with CFRD is postprandial 
hyperglycemia. Acute hyperglycemia, either following a meal or with glucose challenge, results in 
oxidative stress and inflammation in normal subjects, subjects with mild glucose impairment, and 
patients with type 2 diabetes (5-7). This occurs rapidly and can be detected within an hour of 


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glucose challenge (5). Levels of cytokines, such as IL-6 and TNF, are higher and remain elevated 
longer in subjects with high risk prediabetes compared to healthy controls despite an identical 
degree of hyperglycemia (7). Mediation by oxidative stress was shown by studies in which the 
glucose challenge was repeated with the additional administration of glutathione, a powerful 
antioxidant. These studies showed that despite the same degree of hyperglycemia, the presence 
of an antioxidant blocked the increase in cytokine levels completely (7). Thus, hyperglycemia 
appears to induce a pro-inflammatory response via an increase in oxidative stress. 
 
 
 
Effect of Oxidative Stress and Proinflammatory Cytokines on-Cells:  Short periods of 
acute hyperglycemia stimulate insulin gene expression in -cells whereas more prolonged 
episodes of hyperglycemia, as seen in diabetes, can decrease -cell function. This is referred to as 
“-cell glucose toxicity” and oxidative stress is a significant factor in this toxicity (19). There now is 
ample evidence that hyperglycemia-induced oxidative stress impairs -cell function by decreasing 
insulin gene expression, decreasing glucose-dependent insulin secretion, and increasing 
peripheral insulin resistance (19). Hyperglycemia also causes release of pro-inflammatory 
cytokines which can further compromise -cell function by increasing insulin resistance and by 
inducing -cell apoptosis. Inflammatory cytokines that have been shown to contribute to 
destruction of -cells include IL-1, TNF, and IL-6 (20). The concept here is that oxidative stress 
and inflammation induced by acute hyperglycemia can markedly impair -cell function, which in 
turn will further compromise glucose tolerance and thus result in worsening hyperglycemia. 
 
Airway Hyperglycosis:  Respiratory tract fluid in humans, obtained either via nasal lavage 
or bronchoalveolar lavage, has much lower glucose concentrations than plasma but respiratory 
tract glucose concentrations correlate with blood glucose levels (21).  This is consistent with 
studies in animals where the glucose concentration in the fluid lining the lower airway was shown 
to be 1/20 to 1/3 of plasma glucose levels (22, 23). 
 
It is generally accepted that the degree of inflammation in the lower airway can be 
approximated by measuring levels of inflammatory cytokines in exhaled breath condensate (EBC): 
the greatest limitation of this test is that levels may be below the detection limit for some of the 
mediators, particularly in healthy controls. More recently, EBC levels of glucose have been 
validated as an indicator of lower airway glucose concentration (24). Using EBC, it was confirmed 
in humans that airway glucose concentrations are much lower than plasma glucose levels. Even 
with significant elevation of plasma glucose levels (as high as 300 mg/dl), the concentration in the 
airways remained 1/10 of systemic levels. This is true for healthy controls and patients with 
diabetes (type 1 or type 2). In marked contrast, CF patients without diabetes have airway glucose 
levels that are 30% of systemic levels and for patients with CFRD, airway glucose levels are over 
50% of systemic levels (24). It is unclear whether the increase in airway glucose levels in CF is due 
to increased airway permeability and/or failure of the sodium-glucose transporter at the apical 
surface of the cell to transport glucose out of the airway lumen. However, the implication of this 
abnormality is clear - just as acute systemic hyperglycemia can cause systemic oxidative stress 
and inflammation, airway hyperglycosis in CF could result in excess pulmonary oxidative stress 
and inflammation.   
 
 
CF and the Inflammatory Response:  Studies in animals, cells, and humans indicate that 
excess inflammation is an important pathologic feature of CF lung disease. This excess 
inflammation is largely limited to the respiratory tract. Evidence for systemic inflammation can be 


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found during significant respiratory exacerbations, although the origin of these inflammatory 
mediators most likely is the lung. Pulmonary inflammation in CF patients is neutrophil-dominated 
and occurs as early as a few weeks after birth (25). Pro-inflammatory cytokines found in lung 
tissue of patients with CF that are mediators of the excessive inflammatory response are IL-6, IL-8, 
TNFα, and IL-1β (26).  Lung inflammation is found in CF patients in the absence of any signs of 
infection, persists throughout the life of the patient, and is accentuated in the presence of bacteria 
(25, 26).  In vitro and in vivo studies suggest that there is a direct link between expression of 
mutant CF transmembrane conductance regulator (CFTR) and an abnormal inflammatory 
response (27, 28).   
 
 
CF and Oxidative stress:  Major regulators of extracellular redox status are the cysteine 
(Cys)/cystine (CySS) and glutathione (GSH)/glutathione disulfide (GSSG) redox couples.  Recent 
studies have shown that oxidation of the Cys/CySS redox couple decreases cell proliferation and 
promotes apoptosis (29, 30).  Although similar roles for GSH/GSSG have not been elucidated, it is 
very likely that this redox couple acts in a similar manner but may play an even greater role in CF 
pathogenesis as CFTR is also known to be a GSH transporter.  Interestingly, in CF patients, lung 
epithelial cells have normal total GSH but exhibit significantly diminished efflux of GSH through 
CFTR channels at the apical surface. Diminished efflux results in a profoundly decreased 
GSH/GSSG redox ratio (more oxidized) in the epithelial lining fluid of the CF lung which may 
further promote an inflammatory response. In vivo, the degree of oxidation is reflected by systemic 
markers of oxidative stress. These biomarkers are compounds generated by oxidative attack of 
reactive oxygen species on a number of organic substrates (e.g. lipids, carbohydrates, amino 
acids, proteins, nucleotides, etc).  In a preliminary experiment, we measured the amount of 
oxidative stress in clinically stable CF patients by measuring the amount of dissolved reactive 
oxygen metabolites (dROM) in plasma and found significant elevations compared to previous 
measurements from healthy individuals, indicating an increased systemic oxidative burden. 
Similarly, using other markers, several others have shown increased levels of oxidative stress in 
CF, particularly in the respiratory tract (31-33). 
 
 
Incretins and the Therapeutic Use of Dipeptidyl Peptidase IV Inhibitors:  Administration 
of glucose orally results in significantly greater insulin secretion than when glucose is given 
intravenously to achieve the same blood glucose levels as with the oral challenge. This 
observation has led to the study of the molecular signaling between the gut and the pancreas and 
subsequent identification of incretin hormones. Incretin hormones are secreted by the gut in 
response to oral nutrients and their major effect is to increase glucose-dependent insulin secretion 
(34). The two main incretin hormones are GLP-1 and GIP. In vitro studies show that GLP-1 
stimulates insulin secretion through a cAMP-mediated pathway that is largely independent of the 
primary pathway that regulates the glucose-dependent insulin secretory pathway. The glucose-
dependent pathway is initiated through generation of ATP and ultimately causes increases in 
intracellular calcium which triggers exocytosis of insulin secretory granules (12).  Incretin action 
enhances the ability of glucose to stimulate exocytosis and thus incretins potentiate glucose-
sensitive insulin secretion but do not stimulate insulin secretion directly. Although incretins signal 
through an independent pathway, the effect of incretins to promote insulin secretion is generally 
seen only with hyperglycemia (34). Thus, physiologic levels of incretins do not stimulate insulin 
secretion if blood glucose levels are normal, and incretin-based therapies carry little risk of 
hypoglycemia unless incretin levels are supraphysiologic (as can be seen with synthetic incretin 
analogues). The magnitude of the effect of GLP-1 and hyperglycemia on insulin secretion is far 
greater, almost 10 fold greater, than that seen with hyperglycemia alone (12). Finally, both GLP-1 


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and GIP have extremely short half-lives (2 minutes for GLP-1 and 7 minutes for GIP) due to 
degradation of the hormones by the enzyme dipeptidyl peptidase IV (DPP 4) (35). 
 
 
Type 2 DM is a complex, multifactorial disease but an important pathophysiologic 
component is a diminished incretin effect, attributed primarily to loss of beta cell mass and function 
(34, 36). This has led to the development of new therapies aimed at enhancing the effects of GLP-
1 and GIP. Exenatide, a DPP-4 resistant analogue of GLP-1, has been shown to be effective in 
reducing HbA1c levels in type 2 DM (37). However, exenatide must be given as an injection (either 
twice daily or, with a long-lasting preparation, once a week). For many patients, injection-based 
therapy is undesirable. Fortunately, the pharmaceutical industry has developed alternative 
therapeutic agents which raise GLP-1 levels by inhibiting degradation of endogenous GLP-1 by 
DPP 4. This has led to a new class of drugs called gliptins and the development of oral 
formulations that have sustained inhibition of DPP 4. Sitagliptin is one such formulation which is 
taken orally once daily. Several studies have shown efficacy of sitagliptin in reducing HbA1c levels 
in type 2 DM when used as monotherapy or in combination with an oral hypoglycemic agent (34). 
There are many advantages of such an approach besides the fact that it requires a once a day oral 
formulation. This includes a negligible risk of hypoglycemia (because incretin levels remain 
physiologic) as well as few reported drug interactions and side effects (because of the specificity of 
DPP 4 inhibition). Furthermore, there are intriguing data in animals and in vitro suggesting that 
raising GLP-1 levels via inhibition of DPP 4 increases -cell mass by a combination of decreasing 
apoptosis and increasing proliferation (38). Finally, beta cells from younger individual’s exhibit 
more proliferation capacity and greater resistance to glucose-induced apoptosis compared to beta 
cells from older individuals (39). Thus, CF patients with prediabetes, being relatively young, would 
appear to be ideal candidates for testing the ability of DPP 4 inhibition to prevent the progression 
of prediabetes to diabetes. 
 
 
Following FDA approval of sitagliptin and other incretin mimetics for type 2 diabetes, reports 
on potential side effects not seen during the initial trials appeared. For example, there was a 
suggestion of a link between these new drugs and the development of acute pancreatitis. Because 
of this association, CF subjects who had previously had pancreatitis were excluded from this study. 
In addition, because pancreatitis is only seen in CF subjects with pancreatic exocrine sufficiency, 
those with pancreatic sufficiency were also excluded from study.  
 
 
Another example is the concern raised about a potential link with pancreatic cancer. On May 
31, 2013, an article appeared in the New York Times focused on Dr. Peter Butler’s assertion that 
sitagliptin use was associated with precancerous lesions of the pancreas. In the same article, the 
Chief Scientific and Medical Officer of the American Diabetes Association countered that this was 
very controversial and if there were risk, “it would be exceptionally low”. Shortly afterwards, the 
British Medical Journal published an editorial suggesting that this class of drugs may be less safe 
than initially thought and that there may be “unwanted proliferative or inflammatory pancreatic 
effects”.  
 
On June 28, 2013, the NIH convened a workshop on the relationship between incretin 
therapy and pancreatic carcinoma. Epidemiologic studies, studies in rodents, and a report on 
autopsy results in diabetic patients treated with incretin mimetics formed the focus of the 
discussion (40-42). The FDA also reviewed pre-clinical results as well as three additional studies 
submitted at the request of the FDA. The American Diabetes Association, the European 
Association for the Study of Diabetes, and the International Diabetes Federation released a 


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statement summarizing this workshop and their conclusion was that although there was an 
association between diabetes and pancreatic carcinoma, there was “no concerns for pancreatic 
disease” with incretin therapy. 
 
Recent studies and clinical experience suggest that CF individuals may have the same, or 
potentially even less, risk of pancreatic cancer than non-CF people. This contention is based on 
the following. First, pancreatitis is thought to be the precursor of pancreatic cancer. Pancreatitis is 
seen in CF but only with mutations that are associated with pancreatic exocrine sufficiency and 
these mutations are rarely, if ever, associated with CF diabetes. Also, in CF teens and adults, the 
pancreas becomes completely atrophic and is a shrunken, small structure of fat and fibrous tissue 
with very little pancreatic ductal tissue remaining. Thus, the clinical picture of CF would imply CF 
people with pancreatic exocrine insufficiency do not develop pancreatitis and also, based on this 
observation plus that very little pancreatic tissue is present in CF teens and adults, CF people 
would not be expected to have an increased risk of pancreatic cancer. This contention is borne out 
by a recent epidemiologic publication on 344,114 CF patient-years showing no increased risk of 
pancreatic cancer in CF compared to background risk (43). In addition, incretin therapy is expected 
to increase levels of GLP-1 and this effect could be prolonged and is suggested as a potential 
mechanism to stimulate islet cell proliferation. However, CF subjects are shown to have lower 
basal levels of incretins and less of an increase with meals than healthy controls (44) and therefore 
incretin therapy may restore CF GLP-1 level to normal rather than super normal levels. Finally, the 
pathologic data show increase in both exocrine and endocrine cell mass with incretin therapy in 
humans and rodents – this still could be a beneficial effect if signaling pathways for these cells are 
normal – rather than the interpretation taken by some that this is a precursor to abnormal 
proliferation and cancer. 
 
 
Thus, taken together these data do not provide substantive evidence that CF subjects in this 
trial are at increased risk of developing pancreatic cancer. However, given the level of controversy, 
the Sponsor is requesting that the suitable language be added to the consent forms to describe 
this unknown risk.  Below is the language approved by the Emory University IRB: 
 
“Recently, scientists have found that sitagliptin could cause precancer-like spots in the 
pancreas. This was based on research studies in rats and in 20 middle-aged to elderly 
people without CF but with type 2 diabetes that were using sitaglipitin or similar medicines. 
In June 2013, the National Institutes of Health (NIH) with the FDA and the American 
Diabetes Association held a meeting, inviting scientists and doctors to look at this idea more 
closely. They decided that there were not enough immediate concerns that sitagliptin 
caused pancreatic disease or pancreatic cancer to tell patients to stop using the medicine. 
However, it has to be considered a possibility while other researchers and doctors look 
further into it. Our sense is that we do not think this will change the risk of being in the study 
for younger patients with CF, but everyone should be aware of it as a possibility, and 
include it as a risk similar to other rare side effects that all subjects should know about.” 
    
 
 
Summary  
 
Acute systemic hyperglycemia causes oxidative stress and a pro-inflammatory response. 
The pro-inflammatory cytokines induced by hyperglycemia are toxic to islet cells and thus worsen 
glucose intolerance.  If repeated episodes of acute hyperglycemia are allowed to continue 


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unabated, over time the accumulated effect of these repeated episodes of hyperglycemia-induced 
oxidative stress and inflammation can be beta cell failure and the development of diabetes. We 
believe that this process is accelerated in CF because CF lung disease and resultant respiratory 
exacerbations are associated with oxidative stress and inflammation and this will further contribute 
to beta cell damage. In other words, CFRD is primarily due to beta cell failure secondary to 
oxidative stress and inflammation. However, there is a vicious cycle of incremental beta cell 
damage leading to postprandial hyperglycemia and airway hyperglycosis which in turn worsens 
oxidative stress and inflammation. This results in reduced resistance to infection and a respiratory 
exacerbation ensues causing additional oxidative stress and inflammation which further damages 
beta cells and the cycle begins again. Thus, this vicious cycle could provide a molecular 
mechanism for the potent negative impact of the prediabetic state on lung health in CF as well as 
how repeated episodes of acute hyperglycemia in CF subjects with prediabetes could lead to the 
development of CFRD. Accordingly, reduction in hyperglycemia through treatment with sitagliptin 
should reduce hyperglycemia-induced oxidative stress and inflammation, the associated 
progression of pulmonary disease, and the subsequent development of CF diabetes in CF subjects 
with high risk prediabetes.  
 
3. 
OBJECTIVES  
 
Primary  
 
 
 
The primary objective of this study is to show that chronic treatment with sitagliptin in CF 
subjects with high risk prediabetes prevents the conversion to diabetes. 
 
Secondary 
 
 
The secondary objectives are to obtain evidence of biologic plausibility for disease benefit. 
Therefore, we propose to demonstrate that treatment with sitagliptin in CF subjects with high risk 
prediabetes results in a preservation of beta cell function and reduction in airway and systemic 
measures of oxidative stress and inflammation as well as a slower rate of progression of lung 
disease.  
 
4. 
STUDY DESIGN 
 
 
This is a Phase 3, double-blind, placebo-controlled multicenter study of 118 CF subjects 
aged 13 years of age or older who have high risk prediabetes.  *Sites without a sufficient pediatric 
population or expertise may only include adult subjects if approved by the Sponsor. 
High risk prediabetes is defined during the screening visit by performing an OGTT and 
finding high-risk impaired fasting glucose (fasting glucose level between 110 and 125 mg/dl, and/or 
1-hour plasma glucose level of 200 mg/dl or higher, and/or impaired glucose tolerance with 2-hour 
plasma glucose level on OGTT being between 140 and 199 mg/dl).  
Conversion to diabetes is defined when two OGTTs performed at least one week apart are 
abnormal (abnormal = fasting plasma glucose level greater than 125 mg/dl and/or a 2 hour glucose 
level greater than199 mg/dl). 
Upon enrollment, subjects will be randomized to receive either sitagliptin or placebo. Each 
subject will be followed for 15 months to determine if sitagliptin prevents the conversion to frank 
diabetes.  
 


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The following will be done at enrollment and every 6 months: 
 
 an OGTT (with a one-week washout period of study medication) and collection of blood for 
measurement of glucose and insulin levels at 0, 30 minutes and 2 hours during the OGTT to 
determine progression of glucose intolerance and the level of beta cell function;  
 collection of blood at time 0 and 2 hours during the OGTT for measurement of systemic 
redox status, oxidative stress, and degree of inflammation to determine the degree of basal 
oxidative stress and inflammation as well as the degree of hyperglycemia-induced oxidative 
stress and inflammation; 
 if applicable, collection of EBC at time 0 and 2 hours during the OGTT and measurement of 
airway redox status, degree of inflammation, and glucose levels to determine basal 
respiratory tract redox status and inflammation, the degree of hyperglycemia-induced 
changes in redox status and inflammation, and correlation between plasma and airway 
glucose levels; To be completed in a subset of subjects as directed by the study sponsor; 
 collection of blood to determine safety of the study medication (liver and renal function, 
complete blood count, electrolyte concentrations);  
 determination of progression of lung disease as defined by the number of respiratory 
exacerbations severe enough to require hospitalization and the rate of decline in lung 
function.  
 
 
Subjects will also be briefly evaluated half-way between the six-month assessments for 
interval history of intercurrent illnesses and measure of HbA1c. A rise of more than 0.5% from the 
enrollment value will result in two OGTT tests done at least one week apart to determine if 
diabetes has developed. A 0.5% rise in HbA1c was chosen as this degree of increase reflects the 
typical difference between high risk prediabetes and previously unrecognized diabetes detected by 
an OGTT in a given individual (LS Philips, unpublished data) and also the rise seen in those 
individuals with high risk prediabetes who progress to diabetes (13). Conversion to CFRD will be 
defined when both OGTTs are abnormal (abnormal = fasting plasma glucose level greater than 
125 mg/dl and/or a 2-hour glucose level greater than 199 mg/dl).  
 
In the event that diabetes does develop (either documented by OGTTs done at a 6-monthly 
visit, by OGTTs done in the interval between the 6-month visits for an elevation in HbA1c, or), the 
study drug (or placebo) will be stopped and the subject will cease participation in the study as the 
primary outcome – conversion to CFRD – has been reached.    
 
In summary, this is a double-blind, placebo-controlled clinical trial to determine whether 
sitagliptin prevents the conversion of high risk prediabetes to frank diabetes in CF subjects. If 
successful, this would be the first treatment modality available to prevent the development of 
CFRD, a serious and life shortening complication of CF.  
 
5. 
SUBJECT SELECTION CRITERIA 
 
 
At least 118 CF subjects will be enrolled in this study according to the following criteria.  
 
 
Inclusion criteria  
 
 
 
Subjects must meet all the following criteria to be enrolled in this study. 
 
1. Aged 13 years of age or older at the time of enrollment. 
 


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2. Diagnosis of CF confirmed by pilocarpine iontophoresis sweat chloride measurements 
and/or genotyping. 
 
3. Clinically stable with no lower respiratory tract exacerbation requiring intravenous antibiotics 
in the three weeks prior to enrollment. 
 
4. On a stable clinical treatment regimen for at least three weeks prior to enrollment. 
 
5. Male or female. If female, is not lactating and has a negative pregnancy test at screening. If 
female of child bearing potential, must practice effective birth control (i.e. a method known to 
decrease the risk of pregnancy to less than 1%). 
  
6. Able to understand and provide informed consent. 
 
7. Willing and able to comply with the study schedule and testing. 
 
8. High risk prediabetes found on an OGTT performed at screening 8 weeks or less before 
enrollment. 
 
9.  Available by telephone. 
 
10.  Has literacy and language skills required to fill out study material. 
 
 
Exclusion criteria  
 
 
 
Subjects will not be enrolled in this study if they meet any of the following exclusion criteria. 
 
1. Diagnosis of CFRD. 
 
2. Chronic heart failure with NYHA class III/IV, ejection fraction < 25%, or receiving digoxin. 
 
3. Liver disease as defined by ALT or AST three times above the upper limit of normal.  
 
4. Serum creatinine > 1.3 mg/dl for males and > 1.1 mg/dl for females or receiving chronic 
dialysis. 
 
5. Taking chronic systemic glucocorticosteroids during the past month. 
 
6. On insulin therapy during the past month. 
 
7. CF lung disease severe enough to require daytime chronic oxygen therapy via nasal 
cannula during the past month. 
 
8. Unable to perform pulmonary function testing. 
 
9. History of any illness or condition that, in the opinion of the Sponsor might confound the 
results of the study or pose an additional risk in administering study drug to the subject.   
 


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10. Post lung or liver transplant. 
 
11.  Listed and awaiting organ transplant. 
 
12. Current drug or alcohol dependency. 
 
13. Participating in another clinical drug trial or past participant within 30 days of enrollment. 
 
14. Pancreatic sufficient. 
 
15. History of acute pancreatitis as documented by characteristic clinical manifestations and 
elevation of serum amylase and lipase within the last 2 years. 
 
 
6. 
STUDY MEDICATION AND RANDOMIZATION 
 
 
Formulation and Storage 
 
 
The study medication, sitagliptin, will be given as a once daily dose of 100 mg each 
morning. The drug will be supplied by Merck and Co., Inc. The study medication and matching 
placebo is provided as solid white, round tablets.  Tablets will be stored at room temperature.  
 
 
Randomization  
 
 
Subjects who fulfill all the inclusion and exclusion criteria at screening (Visit 1) will be 
randomized at Visit 2 to receive either sitagliptin tablets or placebo tablets. Randomization will be 
done by the research pharmacist at Emory University using a computer generated randomizing 
scheme. Randomization will be stratified by gender.  Subjects will be randomly assigned to 
placebo or sitagliptin in a 1:1 ratio. 
Once conversion to CFRD has been documented by two abnormal OGTT tests done at 
least one week apart, the study drug will be stopped and the subject will cease participation in the 
study. 
 
 
Dispensing and administering study medication  
 
 
At Visit 2 (Week 0), study investigator will instruct the subject on how to store and to self-
administer the tablets. The subject will be instructed to take the tablets by mouth once a day in the 
morning before breakfast and to store the medication kits at room temperature. A 3-month supply 
of the tablets will be given to the subject at that time. The subject will be instructed to bring unused 
study medication kits at each three-monthly visit when the next medication kit will be dispensed. 
 
At Visit 3 (Month 3), the subject will be given a new medication kit and be instructed that the 
study medication needs to be stopped one week before the next visit so the tests can be done. 
Approximately one week prior to Visit 4 (Month 6), the subject will be contacted and reminded to 
stop taking any more study drug until after Visit 4 is completed. At Visit 4, a 3-month medication kit 
will be dispensed and unused kits from the previous three month period collected from the subject. 
This will continue until Visit 6, Month 12. At that visit, no further medication kits will be given as the 
final visit, visit # 7 (Month 15) is a washout visit. 
 


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If the subject develops side effects from the study medication that the investigator feels are 
unacceptable, then the study drug will be stopped and the subject withdrawn from the study.  
 
If the subject develops CFRD, study drug will be stopped, and subject will have completed 
the study.  
 
Drug accountability  
 
 
The research pharmacist at Emory University will receive delivery of the sitagliptin and 
placebo from Merck and Co., Inc. The study drug will be stored at room temperature, separate 
from the hospital stock of medication, and in a secure, locked area that is accessed only by the 
research pharmacist.  
 
The research pharmacist is responsible for randomization as well as packaging and 
dispensing of medication kits at each 3-month visit. He/she will also be responsible for maintaining 
accurate records of study medications dispensed and study medications returned. 
 
Study drug for the Institut de Recherches Cliniques de Montréal, will be shipped directly to 
the site by Merck. Other secondary sites will have study drug shipped directly from the Emory 
research pharmacy.  
 
Study subjects will have study drug accountability performed at each visit to help ensure 
compliance with study drug. If subjects are found to be less than 85% complaint with taking study 
drug, he/she will be counseled and re-educated by study investigator. Study subjects will not be 
withdrawn from the study due to non-compliance with study drug. 
 
Concomitant medications  
 
 
Subjects will continue their chronic therapy for CF throughout the duration of the study. The 
usual CF therapeutic regimen includes pancreatic enzyme replacement therapy, vitamins, inhaled 
medications (antibiotics, recombinant DNAse, bronchodilators, corticosteroids, and hypertonic 
saline), and oral anti-inflammatory agents (azithromycin, nonsteroidal anti-inflammatory drugs). All 
these drugs are permitted during this study but the therapeutic regimen must be unchanged for 
three weeks prior to enrollment. At screening, concomitant medications are documented. Following 
enrollment, changes in the daily, chronic CF therapy can be made at the discretion of the CF 
physician. During acute respiratory exacerbations, oral antibiotics will be prescribed according to 
the antibiotic sensitivity pattern of the most recent sputum culture which is done routinely as part of 
CF clinical care. For respiratory exacerbations severe enough to require hospitalizations, 
intravenous antibiotics (again based on the antibiotic sensitivity pattern of the most recent sputum 
culture) will be initiated as well as increased airway clearance. For specific infections with limited 
treatment options, (such as atypical mycobacterium), clinicians may use chronic IV suppression 
therapy for an extended period of time. These respiratory exacerbations and any other changes in 
clinical status will be recorded as adverse events. Concomitant medications (including chronic CF 
medications, new medications started for the acute illness, and medications stopped due to the 
acute illness) will be documented. The subject  should continue the study drug during the 
hospitalization. Some CF clinicians use a short course (less than 10 days) of systemic 
glucocorticosteroids for CF respiratory exacerbations that do not improve with intravenous 
antibiotics. This is acceptable for patients enrolled in this study provided that the course of 
glucocorticoid treatment lasts three weeks or less. If glucocorticosteroid treatment is needed for a 
longer period of time, such as for the treatment of ABPA, then permission from the Sponsor is 
required for the subject to continue of the study. Finally, during the hospitalization, postprandial 
glucose levels will be monitored as worsening hyperglycemia is frequently seen in CF patients with 


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prediabetes who have a respiratory exacerbation severe enough to require hospitalization. Acute 
hyperglycemia can be treated with insulin during the hospitalization according to the discretion of 
the CF physician. If hyperglycemia persists after completion of the course of intravenous antibiotics 
(the duration of which is usually two to three weeks) or two weeks after the last dose of 
corticosteroids, then the OGTT will be repeated two times at least one week apart. If the OGTTs 
indicate that the subject has developed CFRD (i.e. both OGTTs are abnormal where abnormal is 
defined as fasting plasma glucose greater than 125 mg/dl or a 2 hour level 200 mg/dl or greater) 
then the study drug will be discontinued and the subject will have completed the study.   
 
7. 
EXPERIMENTAL PROTOCOL 
 
 
The Emory University Cystic Fibrosis Center in Atlanta, Georgia will be the coordinating 
center for this project. Subject recruitment, measurement of markers of oxidative stress and 
inflammation, data management, and data analysis will be performed at this center. Additional CF 
Centers, will be enlisted to ensure recruitment of the 118 patients required for the study. Current 
secondary sites include Children’s Healthcare of Atlanta at Scottish Rite in Atlanta, Georgia; the 
University of Iowa in Iowa City, Iowa; and the Institut de Recherches Cliniques de Montreal in 
Montreal, Quebec, Canada. Some procedures for the study will be considered optional for 
secondary sites and will be completed at the discretion of the study sponsor. 
 
 
The schedule of study visits will be as follows: 
 
 Visit 1 – Screening - Up to 8 weeks prior to Visit 2 
 
 Visit 2 – Baseline studies and randomization – Week 0 
 
 Visit 3 – Interval visit #1 – Month 3 
 
 Visit 4 – Detailed assessment #1 – Month 6 
 
 Visit 5 – Interval visit #2 – Month 9 
 
 Visit 6 – Detailed assessment #2 – Month 12 
 
 Visit 7 –Washout Visit – Month 15 
 
 OGTT(s) to diagnose conversion to CFRD  
 
 
 
 
The date of the study visit is defined as the date the subject has his/her blood drawn for an 
OGTT or for safety labs.  For visits 3-7, if the subject is unable to complete all study procedures on 
the same date, the medical history, physical exam and PFTs may be completed within +/- 3 days 
of the date of the study visit.  
 
Enrollment and informed consent 
 
 
 
CF patients attending the CF Clinic who are 13 years of age or over, who are not known to 
have CFRD, and who the CF physician thinks would be appropriate for this study because they do 


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not meet any of the exclusion criteria, will be approached by study personnel as potential 
volunteers for this study.  
 
For sites using two separate consent forms, one consent form is for the screening visit only. 
The screening consent outlines in detail the procedures for the screening visit and explains that the 
goal of the half-day visit is to determine if they have high risk prediabetes and therefore might 
qualify for the clinical trial.  If the screening study shows their glucose status qualifies them for the 
double-blind, placebo-controlled interventional study they will be invited to participate in the clinical 
trial.  
 
Eligible subjects willing to participate in the interventional study will have the study 
procedures explained in detail and questions answered. They will be instructed that the study 
period is 1¼ years and will entail 7 visits in total, 5 of which will require an overnight fast and one 
half day of testing in the morning and two of which will be a short, one hour visit. Informed consent 
will be signed when the subject returns for Visit #2, the enrollment/baseline visit for the 
interventional study. When the patient has been without a respiratory exacerbation requiring IV 
antibiotics or oral steroids and has had no change in chronic medication for two weeks, the subject 
will have the Baseline/Enrollment visit #2.  
 
Some sites will use one consent form that describes the screening visit and the 
interventional study using one form. For those sites, participants will be required to complete 
consent prior to the start of the screening visit. This consent will include information on both the 
screening visit and interventional study visits, should the participant be eligible.   
 
 
 
Visit 1 - Screening (Up to 8 weeks prior to Visit 2) 
 
 
Screening will occur up to eight weeks before study medication is begun. The subject may 
be scheduled for the screening visit once he/she has had no changes in chronic medications and 
without a respiratory exacerbation requiring IV antibiotics or oral steroids for three weeks prior to 
the screening visit. 
 
The subject will be instructed to refrain from alcohol 24 hours before the study visit. The 
subject will also be instructed to have nothing to eat or drink overnight for at least 10 hours, except 
for water, not to take bronchodilators, such as albuterol, xopenex, etc. for a minimum of four hours 
prior to the OGTT and to withhold inhaled steroids, such as Advair (fluticasone), Symbicort, etc; for 
a minimum of 10 hours prior to the OGTT. Bronchodilators and inhaled steroids may be resumed 
at completion of the study visit. The subject will be asked to arrive at the research clinic in the 
morning at their scheduled appointment time for the screening visit. The following will be done 
during the screening visit after informed consent has been obtained: 
 
 Review Inclusion/Exclusion criteria to confirm subject eligibility 
 
 Record medical history  
 
 Perform a physical examination  
 
 Record concomitant medications 
 
 Measure body weight (in kg with coat and shoes off), height (in cm with shoes off), and 
vital signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 


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 After confirming overnight fast a minimum of 10 hours, collect blood for fasting plasma 
glucose levels, HbA1c, chemistry (Na+, K+, Cl-, BUN, and creatinine), hematology 
(complete blood count and differential), liver function (ALT, AST, bilirubin, alkaline 
phosphatase), and serum pregnancy test (hCG) if female.  
 
 
Perform an OGTT by giving glucola orally based on body weight (1.75 g glucola/kg body 
weight to a maximum of 75 g) then measure plasma glucose levels at 1 and 2 hours after 
the glucola. Subjects should be scheduled early enough to ensure glucola is administered 
no later than 11 am. High risk prediabetes will be defined as having a fasting glucose 
between 110 and 125 mg/dl, a 1-hour glucose level of 200 mg/dl or higher, and/or a 2 hour 
glucose level between 140 mg/dl and 199 mg/dl on the OGTT. If the subject did not fast 
overnight, then the OGTT will be rescheduled. Subjects may be allowed to waive the 
screening OGTT if he/she has recently had an OGTT within Emory Healthcare,  including 
the Emory Research Center (CRN), or Children’s Healthcare of Atlanta system for clinical or 
research purposes within a reasonable time frame prior to this visit. Use of previous OGTT 
for screening purposes is at the discretion of the sponsor.  
 
 
Approximately 2 tablespoons (30 mls) of blood will be drawn at this visit. 
 
The investigator will review the subject’s history, physical examination, list of concomitant 
medications, laboratory tests, and results of the OGTT, once available to confirm that the subject 
fulfills inclusion and exclusion criteria. Subjects that do fulfill criteria will be contacted to return for 
Visit 2 (baseline) which will be scheduled up to 8 weeks after the screening visit. Also, at this time 
the subject will be randomized to receive either sitagliptin or placebo by the research pharmacist.  
Subjects that do not fulfill criteria will be discontinued from the study. If the screening OGTT 
reveals that the patient has normal glucose levels, the patient will not be eligible for the study. If 
the screening OGTT shows that the subject has high risk prediabetes (fasting glucose between 
110 mg/dl and 125 mg/dl, 1 hour level of 200 mg/dl or higher, and/or a 2-hour glucose level 
between 140 mg/dl and 199 mg/dl), then the subject can be enrolled into the interventional study if 
willing to participate. If the screening OGTT reveals that the patient has plasma glucose levels in 
the diabetic range (i.e. fasting plasma glucose level > 125 mg/dl and/or 2 hour level > 199 mg/dl), 
the OGTT will be repeated at least one week later. If the second OGTT is diagnostic of CFRD, the 
subject is not eligible for the study and should be referred to an endocrinologist for treatment. If the 
second OGTT is within the normal or high risk prediabetic range, the patient is eligible for 
participation in the primary study. The second OGTT is done when the subject is free of lower 
respiratory tract exacerbation(s) requiring intravenous antibiotics for at least 3 weeks and has been 
on a stable clinical treatment regimen for at least 3 weeks. 
 
 
Visit 2 - Baseline and Randomization (Week 0)   
 
 
The Baseline and Randomization visit is done when the subject has had no changes in 
chronic medications and without a lower respiratory tract exacerbation requiring intravenous 
antibiotics or oral steroids for at least two weeks. 
 
Baseline visit should be scheduled within 8 weeks from the screening visit. 
 
The subject will be instructed to refrain from alcohol 24 hours before the study visit. The 
subject will also be instructed to have nothing to eat or drink overnight for at least 10 hours, except 
for water, and not to take bronchodilators, such as albuterol, xopenex, etc. for a minimum of four 


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hours prior to OGTT or pulmonary function test and to withhold inhaled steroids such as Advair 
(fluticasone), Symbicort, etc. for a minimum of 10 hours prior to the OGTT. Subjects may resume 
bronchodilators and inhaled steroids after completion of the study visit. Subjects will be asked to 
arrive at the research clinic in the morning at their scheduled appointment time for the baseline and 
randomization visit. The following will be done during this visit after informed consent has been 
obtained: 
 
 Confirm subject stability 
 
 Conduct an interval medical history since last study visit  
 
 Perform a physical examination  
 
 Measure body weight (in kg with coat and shoes off), height (in cm with shoes off), and 
vital signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 
 
 Review concomitant medications 
 
 Perform pulmonary function testing (spirometry). If subject is being seen in clinic the same 
day as the study visit, use the clinic PFTs.  
 
 Collect blood for chemistry (Na+, K+, Cl-, BUN, and creatinine), hematology (complete 
blood count and differential), liver function (ALT, AST, bilirubin, alkaline phosphatase), 
HbA1c, and serum pregnancy test (hCG) if female 
 
 Perform an OGTT and EBC, (if applicable) as follows:  
 
1. Collect blood for glucose and insulin levels, measures of oxidative stress (dROM, 
protein carbonyl) and redox couples (GSH/GSSG and cysteine/cystine), and levels 
of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
2. If applicable, EBC for glucose levels, measures of redox couples (GSH/GSSG and 
cysteine/cystine), and levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8)* 
Collection of EBC is optional and is at the discretion of the study sponsor.  
 
3. Administer glucola orally based on body weight (1.75gms glucola/Kg body weight to 
a maximum of 75 gms). Subjects should be scheduled early enough to ensure 
glucola is administered no later than 11 am. 
 
4. At ½  and 2 hours after administration of the glucola, collect blood for glucose and 
insulin levels 
 
5. At 2 hours after administration of the glucola, collect blood for measures of oxidative 
stress (dROM, protein carbonyl), redox couples (GSH/GSSG and cysteine/cystine), 
and levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 


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6. At 2 hours after administration of the glucola, collect EBC, if applicable, for 
measures of glucose levels, redox couples (GSH/GSSG and cysteine/cystine), and 
levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
 Approximately 3 tablespoons plus 1 ½ teaspoon (52 ml) of blood will be drawn at this visit.  
 
 Subjects will be randomized to receive either sitagliptin or placebo as described above, 
given a three-month medication kit, and instructed on storage and daily administration of 
the study medication. The subject will be instructed to start the study medication the next 
day in the morning before breakfast and to take the medication at a similar time each 
morning. An appointment will be made to return to the research clinic in three months and 
the subject will be instructed to bring all unused medication kits to that visit. 
 
Follow-up Visits 
 
 
Visit 3 – Interval Visit #1 (Month 3) 
 
 
 
Visit 3 is a short interval assessment visit, the primary purpose of which is to determine if 
any interval illnesses have occurred since the previous study visit and to assess whether the 
subject has developed CFRD in the intervening three months since the last study visit. The 
following will be done at this interval assessment study visit. 
 
 Perform interval history since the previous study visit with a focus on any interval increase in 
respiratory symptoms, any other intercurrent illnesses, and emergency department visits 
and/or hospitalizations  
 
 Conduct a physical examination (+/- 3 days) 
 
 Measure body weight (in kg with shoes and coat off), height (in cm with shoes off), and vital 
signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 
 
 Review adverse events and if any, all concomitant medications 
 
 Perform pulmonary function testing (spirometry).  If subject is being seen in clinic the same 
day as the study visit, use the clinic PFTs. (+/- 3 days) 
 
 Collect blood for chemistry (Na+, K+, Cl-, BUN, and creatinine), hematology (complete blood 
count and differential), liver function (ALT, AST, bilirubin, alkaline phosphatase), and serum 
pregnancy test (hCG) if female. Collect blood for HbA1c. Approximately 1 ½ tablespoons 
(22 mls) of blood will be drawn at this visit unless patients are scheduled to have annual 
clinical labs drawn as a part of routine clinic visit.  
 
 If the HbA1c is elevated by more than 0.5% from the baseline value at the time of 
enrollment and if the subject is well with no intercurrent illness, the subject will be instructed 
to stop study drug. An OGTT will be performed at minimum one week later and then 
repeated, one to four weeks later, again off study drug. 


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If the subject has an intercurrent illness, the study drug will be continued and the illness will 
be treated by the CF clinical team. Once the subject has been clinically stable and without 
any new medications for two weeks, (excluding chronic IV suppression therapy used for the 
treatment of mycobacteria taken greater than 6 weeks duration) the subject will be 
instructed to stop the study drug and the two OGTTs done as above.  
 
Conversion to CFRD will be defined when both OGTTs are abnormal (abnormal = fasting 
plasma glucose level greater than 125 mg/dl and/or 2 hour glucose level greater than199 
mg/dl). If the subject has developed CFRD then the study medication will be stopped and 
the subject will have completed the study and a referral to a CF endocrinologist will be 
made. If both OGTTs are not abnormal, study drug will be restarted and the subject will 
proceed with the study.  
 
If the HbA1c level is not elevated by more than 0.5% from the baseline value at the time of 
enrollment, the subject will be given a 3-month medication kit and will be instructed to 
continue the study medication until one week prior to the next visit and to bring all used and 
unused study medication kits to that visit.   
 
The subject will be instructed to continue the study medication until one week prior to the 
next visit and to bring all used and unused study medication kits to that visit. Study drug 
accountability and compliance with study drug to be reviewed.  
 
 All subjects will have an appointment date set in three months for the detailed assessment 
visit and will be instructed to fast for 10 hours overnight before that visit.  
 
 
 Visit 4 - Detailed Assessment Visit #1 (Month 6) 
 
 
The Detailed Assessment Visit is done when the subject has been without a respiratory 
exacerbation requiring intravenous antibiotics (excluding chronic IV suppression therapy for the 
treatment of mycobacterium greater than 6 weeks duration, with sponsor approval), or oral steroids 
for at least two weeks.  
 
The subjects with high risk prediabetes will be contacted approximately one week prior to 
the visit to remind them to stop the study medication and to bring all unused medications to the 
visit. All subjects will be contacted  prior to this study visit and instructed to refrain from alcohol 24 
hours before the study visit, to have nothing to eat or drink except for water overnight for at least 
10 hours, not to bronchodilators, such as albuterol, xopenex, etc. for a minimum of four hours prior 
to OGTT or pulmonary function test, and to withhold inhaled steroids, such as Advair (fluticasone), 
Symbicort, etc. for a minimum of 10 hours prior to the OGTT. Bronchodilators and inhaled steroids 
may be resumed at the completion of the study visit. Subjects will be asked to arrive at the 
research clinic in the morning at their scheduled appointment time for the detailed assessment 
visit. Subjects may resume bronchodilators after completion of the study visit. The following will be 
done during the detailed assessment visit: 
 
 Confirm subject stability 
 
 Conduct an interval medical history since the previous study visit with a focus on any 
interval increase in respiratory symptoms, any other intercurrent illnesses, and emergency 
department visits and/or hospitalizations  (+/- 3 days) 


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 Perform a physical examination (+/- 3 days) 
 
 Measure body weight (in kg with shoes and coat off), height (in cm with shoes off), and 
vital signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 
 
 Review adverse events and if any, record all concomitant medications 
 
 Perform pulmonary function testing (spirometry). If subject is being seen in clinic the same 
day as the study visit, use the clinic PFTs. (+/- 3 days)  
 
 Collect blood for chemistry (Na+, K+, Cl-, BUN, and creatinine), hematology (complete blood 
count and differential), liver function (ALT, AST, bilirubin, alkaline phosphatase), and 
serum pregnancy test (hCG) if female 
 
 Perform an OGTT as follows: 
 
1. Collect blood for glucose and insulin levels, measures of oxidative stress (dROM, 
protein carbonyl) and redox couples (GSH/GSSG and cysteine/cystine), and levels 
of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
2. If applicable, collect EBC for glucose levels, measures of redox couples 
(GSH/GSSG and cysteine/cystine), and levels of pro-inflammatory cytokines (TNF, 
IL-6, and IL-8) * Collection of EBC is optional and is at the discretion of the study 
sponsor. 
 
3. Administer glucola orally based on body weight (1.75gms glucola/Kg body weight to 
a maximum of 75 gms)  
 
4. At ½ and 2 hours after administration of the glucola, collect blood for glucose and 
insulin levels 
 
5. At 2 hours after administration of the glucola, collect blood for measures of oxidative 
stress (dROM, protein carbonyl), redox couples (GSH/GSSG and cysteine/cystine), 
and levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
6. At 2 hours after administration of the glucola, collect EBC, if applicable, for 
measures of glucose levels, redox couples (GSH/GSSG and cysteine/cystine), and 
levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
 Approximately 3 tablespoons plus 1 teaspoon (50 ml) of blood will be drawn at this visit.  
 
 Glucose levels from the OGTT will be analyzed within one week of study. If the results of 
the OGTT indicate that the subject may have developed CFRD (as defined by a fasting 
plasma glucose level greater than 125 mg/dl and/or a 2 hour glucose level greater than199 
mg/dl on the OGTT) then the study medication will be stopped.  A second OGTT will be 


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performed at minimum one week later, again off study drug. If the subject develops an 
intercurrent illness immediately after this visit and before the second OGTT can be done, 
the illness will be treated by the CF clinical team. Once the subject has been clinically 
stable and without any new medications for two weeks,the second OGTT will be 
performed. Conversion to CFRD will be defined when both OGTTs are abnormal 
(abnormal = fasting plasma glucose level greater than 125 mg/dl and/or a 2 hour glucose 
level greater than199 mg/dl). If the subject has developed CFRD then the study drug will 
be stopped and the subject will have completed the study and a referral to a CF 
endocrinologist will be made. If the subject has not developed CFRD (both OGTTs are not 
abnormal), then the study drug will be restarted and the subject will continue with the 
study.  
 
Unused study drug to be collected and study drug accountability and compliance to be 
reviewed. Subjects will be given a three-month medication kit and will be instructed to 
bring all unused medication kits to the next study visit.  
 
 For all subjects, an appointment will be made for the next study visit in three months.  
 
 
 
Visit 5 – Interval visit #2 (Month 9) 
 
 
 
Visit 5 is a short interval assessment visit, the primary purpose of which is to determine if 
any interval illnesses have occurred since the previous study visit and to assess whether the 
subject has developed CFRD in the intervening three months since the last study visit. The 
following will be done at this interval assessment study visit. 
 
 
 Perform interval history since the previous study visit with a focus on any interval increase in 
respiratory symptoms, any other intercurrent illnesses, and emergency department visits 
and/or hospitalizations (+/- 3 days) 
 
 Conduct a brief physical examination focused on the respiratory system (+/- 3 days) 
 
 Measure body weight (in kg with shoes and coat off), height (in cm with shoes off), and vital 
signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 
 
 Review adverse events and if any, record all concomitant medications 
 
 Perform pulmonary function testing (spirometry). If subject is being seen in clinic the same 
day as the study visit, use the clinic PFTs. (+/- 3 days) 
 
 Collect blood for chemistry (Na+, K+, Cl-, BUN, and creatinine), hematology (complete blood 
count and differential), liver function (ALT, AST, bilirubin, alkaline phosphatase), and serum 
pregnancy test (hCG) if female; Collect blood for HbA1c. Approximately 1 ½ tablespoons 
(22 mls) of blood will be drawn at this visit unless patients are scheduled to have annual 
clinical labs drawn as a part of routine clinic visit. 
 


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 If the HbA1c is elevated by more than 0.5% from the baseline value at the time of 
enrollment and if the subject is well with no intercurrent illness, the subject will be 
instructed to stop the study drug. An OGTT will be performed at minimum one week later 
and then repeated, one to four weeks later, again off study drug.  If the subject has an 
intercurrent illness, the study drug will be continued and the illness will be treated by the 
CF clinical team. Once the subject has been clinically stable and without any new 
medications for two weeks, the subject will be instructed to stop the study drug and the two 
OGTTs done as above. Conversion to CFRD will be defined when both OGTTs are 
abnormal (abnormal = fasting plasma glucose level greater than 125 mg/dl and/or 2 hour 
glucose level greater than199 mg/dl). If the subject has converted to CFRD then the study 
drug will be stopped and the subject will have completed the study and a referral to a CF 
endocrinologist will be made. If both OGTTs are not abnormal, then the study drug will be 
restarted and the subject will continue on the study. 
 
 Subjects whose HbA1c level is not elevated by more than 0.5% from the baseline value will 
proceed with study visit. 
 
 Unused study drug to be collected and study drug accountability and compliance to study 
drug to be reviewed. Subject   will be given a three-month medication kit and will be 
instructed to continue the study medication until one week prior to the next visit and to bring 
all used and unused medication kits to the next study visit.  
 
  All subjects will have an appointment date set in three months for the detailed assessment 
visit and will be instructed to fast for 10 hours overnight before that visit. 
 
 
 
Visit 6 - Detailed Assessment Visit #2  & Termination of Study Drug (Month 12) 
 
 
The Detailed Assessment Visit is done when the subject has been without a respiratory 
exacerbation requiring intravenous antibiotics (excluding chronic IV suppression therapy used for 
treatment of mycobacteria greater than 6 weeks duration, with sponsor approval) or oral steroids 
for at least two weeks.  
 
The subjects will be contacted approximately one week prior to the visit to remind them to 
stop the study medication and to bring all unused medications to the visit. All subjects will be 
contacted prior to this study visit and instructed to refrain from alcohol 24 hours before the study 
visit, to have nothing to eat or drink except for water overnight for at least 10 hours, not to take 
bronchodilators, such as albuterol, xopenex, etc. for a minimum of four hours prior to OGTT or 
pulmonary function test, and to withhold inhaled steroids, such as Advair (fluticasone), Symbicort, 
etc. for a minimum of 10 hours prior to the OGTT. Bronchodilators and inhaled steroids may be 
resumed after completion of the study visits. Subjects are asked to arrive at the research clinic in 
the morning at their scheduled appointment time for the detailed assessment visit. Subjects may 
resume bronchodilators after completion of the study visit. The following will be done during the 
detailed assessment visit: 
 
 Confirm subject stability 
 
 Perform interval medical history since the previous study visit with a focus on any interval 
increase in respiratory symptoms, any other intercurrent illnesses, and emergency 
department visits and/or hospitalizations  (+/- 3 days) 


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 Perform a physical examination (+/- 3 days ) 
 
 
 Measure body weight (in kg with shoes and coat off), height (in cm with shoes off), and 
vital signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 
 
 Review adverse events and if any, record all concomitant medications 
 
 Perform pulmonary function testing (spirometry). If subject is being seen in clinic the same 
day as the study visit, use the clinic PFTs. (+/- 3 days)  
 
 Collect blood for chemistry (Na+, K+, Cl-, BUN, and creatinine), hematology (complete 
blood count and differential), liver function (ALT, AST, bilirubin, alkaline phosphatase), and 
serum pregnancy test (hCG) if female 
 
 Perform an OGTT as follows: 
 
1. Collect blood for glucose and insulin levels, measures of oxidative stress (dROM, 
protein carbonyl) and redox couples (GSH/GSSG and cysteine/cystine), and levels 
of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
2. Collect EBC for glucose levels, measures of redox couples (GSH/GSSG and 
cysteine/cystine), and levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8)  
                       * Collection of EBC is optional and is at the discretion of the study sponsor. 
 
3. Administer glucola orally based on body weight (1.75gms glucola/Kg body weight to 
a maximum of 75 gms)  
 
4. At ½ and 2 hours after administration of the glucola, collect blood for glucose and 
insulin levels 
 
5. At 2 hours after administration of the glucola, collect blood for measures of oxidative 
stress (dROM, protein carbonyl), redox couples (GSH/GSSG and cysteine/cystine), 
and levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
6. At 2 hours after administration of the glucola, collect EBC, if applicable,  for 
measures of glucose levels, redox couples (GSH/GSSG and cysteine/cystine), and 
levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) 
 
 Approximately 3 tablespoons plus 1 teaspoon (50 ml) of blood will be drawn at this visit.  
 
 Glucose levels from the OGTT done this study visit will be analyzed within one week of 
study. If the results of the study OGTT indicate that the subject may have developed CFRD 
(as defined by a fasting plasma glucose level greater than 125 mg/dl and/or a 2 hour 


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glucose level greater than199 mg/dl on the OGTT) then the subject will have completed 
the study and a referral to a CF endocrinologist will be made.  
 
Visit 7 – Washout study – Month 15 
 
 
This visit is only for subjects that have completed the 12 month study without converting to 
CFRD. At the end of Visit 6, the subject will have been taken off the study drug and this visit will be 
done after the subject has been off study drug for 3 months.  
 
The subject will be instructed to refrain from alcohol 24 hours before the study visit. The 
subject will also be instructed to have nothing to eat or drink except for water overnight for at least 
10 hours, not to take beta-2 agonists (albuterol/xopenex, etc., commonly referred to as 
bronchodilators and used for CF treatment) for a minimum of four hours prior to OGTT or 
pulmonary function test, and to arrive at the research clinic in the morning at their scheduled 
appointment time for the washout visit. Subjects may resume bronchodilators after completion of 
study visit. The following will be done during the visit: 
 
 Perform interval medical history since the previous study visit with a focus on any interval 
increase in respiratory symptoms, any other intercurrent illnesses, and emergency 
department visits and/or hospitalizations  (+/- 3 days) 
 
 Perform a physical examination (+/- 3 days) 
 
 Measure body weight (in kg with shoes and coat off), height (in cm with shoes off), and vital 
signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 
 
 Review adverse events and if any, record changes in  concomitant medications 
 
 Collect blood for fasting glucose and insulin. 
 
 Perform an OGTT by giving glucola orally based on body weight (1.75gms glucola/Kg body 
weight to a maximum of 75 gms) then measure plasma glucose and insulin levels at ½ hour 
and 2 hours after the glucola. If the OGTTs is abnormal (abnormal = fasting plasma glucose 
level greater than 125 mg/dl and/or 2 hour glucose level greater than199 mg/dl) the subject 
will be referred to the CF endocrinologist for further evaluation and management of their 
diabetes.  
 
 Approximately 5 teaspoons (22 ml) of blood will be drawn at this visit.  
 
 
OGTT(s) to diagnose conversion to CFRD  
 
 
As outlined in the sections above on experimental protocol, two OGTTs are needed to 
diagnose conversion to CFRD. The trigger for having 2 OGTTs done are: 
1. The HbA1c is elevated by more than 0.5% from the baseline value at the time of enrollment. 
2. OGTT results at the detailed study visit indicate the subject may have developed CFRD, i.e. 
fasting plasma glucose greater than 125 mg/dL and/or 2 hour plasma glucose level greater 
than 199 mg/dl, on detailed visit 


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The subject will be instructed to stop study drug for a minimum of 7 days prior to the repeat 
OGTT.  If subject is experiencing an intermittent illness, the illness should be treated clinically and 
the OGTT should be postponed until the subject has been clinically stable for at least 2 weeks. 
 
The subject will be instructed to refrain from alcohol 24 hours before the study visit. The 
subject will also be instructed to have nothing to eat or drink overnight for at least 10 hours, except 
for water, not to take beta-2 agonists (albuterol/xopenex, etc., commonly referred to as 
bronchodilators and used for CF treatment) for a minimum of four hours prior to OGTT, and to 
arrive at the research clinic in the morning at their scheduled appointment time for the repeat 
OGTT. Subjects may resume bronchodilators after completion of study visit. The following will be 
completed: 
 
 Measure body weight (in kg with coat and shoes off), height (in cm with shoes off), and 
vital signs to include oral temperature, heart rate, respiratory rate, transcutaneous oxygen 
saturation, and systolic and diastolic blood pressure after sitting quietly for 5 minutes 
 
 Collect blood for fasting plasma glucose levels  
 
 Perform an OGTT by giving glucola orally based on body weight (1.75 g glucola/kg body 
weight to a maximum of 75 g) then measure plasma glucose levels at 2 hours after the 
glucola. Subjects should be scheduled early enough to ensure glucola is administered no 
later than 11 am.  
 
 Approximately 2 teaspoons (10 ml) of blood will be drawn at this visit. 
 
 
Subject withdrawal  
 
The subject may withdraw from the study at any time by requesting to be withdrawn. The 
reason for the withdrawal will be recorded and the subject will return all medication kits. 
 
The subject may also be withdrawn from the study by the investigator. Finally, the CF 
physician may request of the investigator that the subject be withdrawn from the study. In these 
two situations, the reason for the withdrawal will be recorded and the subject will return all 
medication kits. 
 
Reasons why the investigator would withdraw the subject from the study include: 
 
 Adverse events potentially attributable to the study medication and that are unacceptable to 
the subject and/or the CF physician 
 
 Development during the course of the study of one of the exclusion criterion that could, in 
the opinion of the investigator, impact negatively on the safety of the subject or the 
assessment of efficacy of the study drug 
 
 Subject is noncompliant with protocol procedures 
 
 The subject becomes pregnant  
 
 Death of the subject 
 
 
 


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8. 
SPECIFIC METHODOLOGY 
 
Oral glucose tolerance test (OGTT)  
 
The OGTT is assumed as the “gold standard” for the detection of high risk prediabetes and 
the diagnosis of diabetes. OGTT is performed as follows. After an overnight 10 hour fast, an 
intravenous needle is inserted into an arm vein and blood for glucose and insulin levels are 
collected. Glucola is then given orally based on the subject’s body weight (1.75 gms glucola/Kg 
body weight to a maximum of 75 gms) and should be given no later than 11 am. Blood is collected 
at 30 minutes and 2 hours after administration of the glucola for measurement of insulin and 
glucose levels.  
 
Exhaled breath condensate (EBC)  
* Collection of EBC is optional and is at the discretion of the study sponsor. 
 
EBC is thought to be representative of the microenvironment of the lower airway. This 
concept is based on the premise that an aerosol of respiratory droplets containing solutes and 
water vapor is exhaled during tidal breathing (45).  When the breath is cooled, the water vapor and 
respiratory droplets change from a gas to a liquid phase. The resulting condensate can be 
analyzed for constituents including cytokines, measures of oxidative stress, and glucose.  
 
 
In sites collecting EBC, EBC will be collected for 10 minutes through a polypropylene breath 
collection device with a one-way inhalation valve and condensation tube chilled at -20º C 
(RTube,TM Respiratory Research, Charlottesville, VA).  Participants will be asked to breathe 
relaxed tidal breaths through the device, taking small breaks if needed.  Approximately 2.0 ml of 
EBC is collected during this time frame from vast majority of subjects. If the amount of EBC is less 
than 2 ml, participants will be asked to breathe through the device for an additional 10 minutes. 
Breath samples will be placed on ice and stored at -80oC for later analysis. Batch analysis will be 
done once a month. 
 
Redox status and markers of oxidative stress 
 
Plasma redox status is measured by determining thiol redox couples (GSH/GSSG, 
CYS/CYS2).  The d-ROM assay will determine the amount of reactive oxygen metabolites and is a 
marker for oxidative stress. Protein carbonyls assess the degree of oxidative stress by determining 
the degree of modification of proteins.  For thiol redox pair measurement, samples will be 
processed to form N-dansyl derivatives and analyzed by HPLC with fluorescence detection.  The 
d-ROM test is a spectrophotometric test that allows for the assessment of concentration of 
peroxides (ROOH).  Such compounds are generated in cells by oxidative attack of reactive oxygen 
species on a number of organic substrates (e.g. lipids, carbohydrates, amino acids, proteins, 
nucleotides, etc)  In the d-ROM test, the peroxides in blood react with a chromogenic substrate 
(Diacron international, Italy) to develop a colored derivative (pink to red) that is quantifiable by 
absorbance spectrophotometry. Protein carbonyls will be measured using the Protein carbonyl kit 
supplied by Cayman Chemical (Ann Arbor, MI) per the manufacturer’s instructions. 
 
Pro-inflammatory cytokine assays 
 
 
We use the Bio-Plex flow cytometery HTP system by Bio-Rad to quantify cytokine 
concentrations.  Cytokines to be measured include IL-6, IL-8, and TNF.  Bio-Plex flow cytometery 
is a very sensitive method, especially designed to analyze microsphere based multiplex protein 


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assays. BioPlex techniques are an alternative to using ELISA assays to determine the 
concentration of specific proteins in solution. The advantage of doing multiplex assays is that 
simultaneous measurement for many proteins can be achieved using a very small volume (50 μl). 
To detect and quantify each captured analyte, a fluorescently labeled reporter molecule that 
specifically binds to the analyte is added. Following incubation, the contents of each microplate 
well are drawn into the Bio-Plex array reader, and precision fluids align the beads in single file 
through a flow cell, where two lasers excite the beads individually. One excites the dyes in each 
bead, identifying its spectral address, and the other excites the reporter molecule associated with 
the bead, which allows quantitation of the captured analyte. High-speed digital signal processors 
and Bio-Plex Manager software record the fluorescent signals simultaneously for each bead, 
translating the signals into data for each bead-based assay. 
 
           Pulmonary function testing and pulmonary status  
 
 Pulmonary function testing (spirometry) and interval respiratory history will be obtained 
every three months so rate of decline and the number of significant respiratory exacerbations while 
taking the study medications can be calculated. For detailed visits, subjects may opt to complete 
pulmonary function test during regular clinic appointment if the clinic appointment takes place on 
the same day as the research visit. Subjects must not take beta-2 agonists (albuterol/xopenex, 
etc., commonly referred to as bronchodilators and used for CF treatment) for a minimum of four 
hours prior the pulmonary function test. Bronchodilators may be resumed after completion of study 
visit.  
9. 
SAFETY ASSESSMENTS  
 
Safety of the study medications will be assessed by examination of adverse events, the 
interval medical history, physical examination and vital signs, concomitant medications, and clinical 
laboratory testing.  
 
            Adverse events  
 
           An adverse event (AE) is any untoward medical occurrence associated with the use of a 
drug in humans, whether or not considered drug related.  
 
Over 90% of the morbidity in CF is due to respiratory dysfunction and so in order to more 
readily be able to identify an increase in the frequency of respiratory exacerbations in subjects; 
adverse events will be classified as respiratory or non-respiratory events. Respiratory events are 
defined as any increase in respiratory symptoms and/or signs (increase sputum production, 
increase in cough, runny or stuffy nose, a cold, decrease in lung function, and/or change in 
physical findings of the respiratory system). Non-respiratory adverse events are those that involve 
any organ system other than the respiratory system. A separate respiratory or non-respiratory CRF 
is to be filled out for each event and the event recorded in the respiratory or the non-respiratory 
adverse event log. 
 
AEs can include: 
 
Clinically significant change in physical signs or symptoms  
 
Abnormal laboratory values,  
 
Changes in vital signs, physical examinations, etc.;  
 
An increase in frequency or intensity of a baseline condition,  


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 
Complications from a surgery or procedure. 
 
Drug interactions not defined in Investigator’s Brochure or Package Insert 
 
A Serious Adverse Event (SAE) or Serious Suspected Reaction (SSR) is one that results in:  
 Death 
 Is life threatening  
 Requires inpatient hospitalization or prolongation of an existing hospitalization 
 Results in persistent or significant incapacity or substantial disruption of the ability to 
conduct    normal life functions 
 Is a congenital anomaly/birth defect 
 Based on appropriate medical judgment, event jeopardizes subject and may require 
medical or surgical intervention to prevent one of the above mentioned outcomes. 
 
Suspected Adverse Reaction: any AE for which there is a Reasonable possibility that the drug 
caused the AE 
 
When reporting AEs and SAEs be sure to include the following: 
 Definition of Event: Diagnosis, signs or symptoms 
 Define seriousness: AE vs. SAE 
 Determine if the AE is expected/unexpected 
 Define severity/intensity 
 Relationship to study drug (Causality) 
 
The FDA expects the investigator to make the determination of causality/relatedness and 
severity/intensity. Under the new Safety Reporting Rules, both Sponsors and Investigators can 
assess causality/relatedness. 
 
Expected/Unexpected Classification: 
 
 EXPECTED: An adverse event is expected if: 1) the adverse event is a known side 
effect of the study drug based on previous research and/or listed in the Investigator’s 
Brochure; 2) the event is known to be a complication of the disease under study and/or 
due to the natural progression of the disease; or 3. The event is a known complication 
of the treatments used in the disease. 
 
 UNEXPECTED: An adverse event is unexpected if: 1) the event is not reported in the 
Investigator’s Brochure or previous literature on the study drug; 2) the event is not a 
known complication of the disease or treatment of the disease; or 3) event(s) occur(s) 
with greater severity or frequency than previously reported. 
 
 
Intensity Classification: 
 
Respiratory AE’s Only: 
 
MILD = upper respiratory symptoms only 
 
MODERATE = lower respiratory symptoms treated as an outpatient 
 
SEVERE = lower respiratory symptoms requiring hospitalization 


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Non-respiratory AEs Only: 
 MILD = no medical intervention required. 
 MODERATE = requires minimal, local, or noninvasive intervention. 
 SEVERE = requires hospitalization or invasive intervention. 
 
Causality Classification: 
 
The investigator will also assess causality and judge whether there is a potential that the adverse 
event is related to the study medication. 
 
 UNRELATED = adverse event is judged to be related to the subject’s underlying CF 
and/or treatment for CF. 
 POSSIBLY RELATED = the investigator does not know whether it is related or not to 
the study medication. 
 RELATED = adverse event is judged to be related to the study medication 
 
The event does not necessarily have to have a causal relationship with the study medication.  
 
For this study, the reporting period for adverse events is from the time the subject signs the 
interventional ICF and becomes randomized to 90 days after taking the last dose of the study 
medication.  
 
Adverse events will be recorded in the CRF. All clinically significant adverse events that continue at 
termination of or withdrawal from the study will be followed up by the investigator. Additional tests 
may be necessary until the underlying cause is identified or the situation resolved.  
 
 
Reporting Requirements 
 
If an event is: 
 
 Serious AE (respiratory or non-respiratory) AND unexpected AND related to study drug 
must be reported to the sponsor by telephone and FAX within 48 hours of knowledge of the 
event. The site must also obtain confirmation from the sponsor that the report was received. 
The sponsor is then required to report to the FDA within 15 calendar days of first knowledge 
of the event. If the event is also fatal or life-threatening then the sponsor must report to the 
FDA via telephone or fax within 7 calendar days of first knowledge of the event and a written 
report must be filed within 8 additional calendar days.  
 
 Serious, non-respiratory AEs that are not related to the study drug should be sent to the 
sponsor via FAX within 2 calendar days of knowledge of the event. 
 
 Serious, respiratory AEs not considered to be a standard Cystic Fibrosis exacerbation 
should be sent to the sponsor within 2 calendar days of knowledge of the event. 
 
 Serious, respiratory AEs considered to BE a standard Cystic Fibrosis exacerbation do NOT 
need to be sent to the sponsor but rather entered into the CRF. 
 
 


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Sites should ensure that all AEs/SAEs are entered into CRF as soon as information is received 
and all attempts should be made to close/end any open AEs within 14 days of completion of the 
event. 
 
 For reporting AEs:  
 
 Fax: 404-712-0920 
 Phone: 404-712-2657 
 
Pregnancy  
 
 
Female subjects will have a pregnancy test performed every three months during a study 
visit. A negative pregnancy test must be confirmed at each study visit before study medication is 
administered. Subjects who become pregnant during the study will be withdrawn from the study 
immediately. The pregnancy will be recorded as a protocol violation. The outcome of the 
pregnancy will be monitored by the investigator and any complication of the pregnancy will be 
recorded as an adverse event.  
 
Abnormal clinical laboratory test results  
 
 
The criteria for determining whether an abnormal clinical laboratory test result should be 
reported as an adverse are as follows: 
 
 The test result is associated with new symptoms or signs that were not present at baseline 
 
 The test result requires further diagnostic testing or therapeutic intervention 
 
 The test result results in discontinuation of the study medication or significant additional 
concomitant medication 
 
 The test result is considered an adverse event by the investigator. 
 
 
10. 
DATA SAFETY AND MANAGEMENT 
 
 
Data Safety Monitoring Board (DSMB)  
 
Oversight for this trial will be conducted by the Cystic Fibrosis Foundation Therapeutics 
(CFFT) Data and Safety Monitoring Board (DSMB) Chair, Wayne J. Morgan, MD.  A subcommittee 
called a Data Monitoring Committee (DMC) will serve as the review board for this trial.  The DMC is 
an independent group consisting of individuals who have experience and expertise in the 
management of participants within this disease area, experience in statistical methods, experience 
in safety monitoring and experience in the monitoring of randomized clinical trials.  The members 
of the DMC were formally appointed by the CFFT DSMB Chair in consultation with the Sponsor.  
The DMC is composed of the following individuals: 


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Data Monitoring Committee members and Program Coordinator 
Expertise (Specialty) 
Institution, City, Country 
Contact Information 
John McBride MD, Chair 
- Pulmonologist 
Children’s Hospital Medical 
Center of Akron, Akron, 
OH 
Phone: 330-543-8906 
Email: jmcbride@chmca.org 
Antoinette Moran MD, 
Member – CF 
Endocrinologist 
University of Minnesota, 
Minneapolis, MN 
Phone: 612-624-5409 
Email: moran001@umn.edu 
Randall Young, Jr. MD, 
Member - Pulmonologist 
Albert Einstein Medical 
Center 
Klein Professional 
Building, Room 363 
Phone:  215-456-8304 
Email:  younggkr@einstein.edu 
John Conlon PhD, 
Member - Biostatistician 
Independent 
Biostatistician, Blue Bell, 
PA 
Phone: 267-872-6603 
Email: jconlon17@comcast.net 
Miriam H. Bennett 
CFFT DSMB 
Program Coordinator, 
Sr. 
 
University of Arizona 
Respiratory Sciences 
1501 N. Campbell Avenue 
box 245030, room 2306B 
Tucson, AZ 85724 
Phone: 520-626-8407 
Fax: 520-626-8800 
Cell: 520-909-6796 
Email: mhunt@arc.arizona.edu 
The DMC is responsible for monitoring the safety of the trial participants, ensuring that the trial 
is being conducted with the highest scientific and ethical standards and making appropriate 
recommendations based on review of the data.   Briefly, the DMC will be responsible for: 
- 
Approving the charter which outlines responsibilities, functions, rules of conduct, and the 
basis for monitoring the trial. 
- 
Reviewing the study protocol and any amendments or modifications during the course of the 
trial and advising the Sponsor on any concerns. 
- 
Reviewing serious adverse events (SAEs) and toxicity data. 
- 
Examining accumulated safety data in order to make recommendations concerning 
continuation, termination or modification of the trial based on the effects of the interventions 
under study. 
- 
Reviewing the general progress of the study with regard to accrual, protocol violations, and 
study conduct.  
 
 
Data Management  
 
 
The data management team at the Department of Biostatistics, School of Public Health at 
Emory University will develop a centralized, web-based relational database for data acquisition and 
storage for this project. CRFs will be designed through a joint effort between study investigators 
and biostatistics personnel.  All CRFs will be designed with FrameMaker.  Form questions and lay-
out will be optimized for ease of forms completion and ease of data entry.  The desktop publishing 
of the forms will be done by the data management team, and the forms will feature easy-to-read 
fonts with appropriate sized spaces for responses. 
 
Microsoft’s Structured Query Language (MS SQL) server 2000 database will be used for 
data collection and storage. MS SQL server 2000 database is an American National Standards 


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Institute (ANSI) compliant relational database management system.  MS SQL server 2000 runs on 
a Sun server under the Solaris operating system (UNIX). The data management group has 
successfully used the MS SQL server 2000 database as the back-end database for several 
applications.  The database tables and systems will be tested and validated prior to the start of 
each study.  The data model will be tested and normalized to reduce data redundancies.   
Relationships (such as one-to-one and one-to-many) among data tables will be established to 
accommodate study hypotheses. Each study participant will be assigned a unique identifier that 
will enable programmers to merge data across projects. The database application will be flexible 
enough to add new variables to an existing CRF or to add a new CRF.  
 
Data entry will be distributed and the study database will be centralized, that is, staff 
members will see patients, collect data, complete CRFs, and enter the data into a centralized 
database.  Data collection will be done on traditional paper forms and these forms will be keyed by 
study staff into the web forms. The data entry applications will be web based forms developed 
using DreamWeaver MX 7.00 software with ColdFusion 7.0 scripting language, JavaScript, and 
HTML, following the format of the paper forms to make it easy for data entry personnel to keep 
their place during data entry.  Use of the web for data forms will provide platform independence.  A 
staff member will be able to enter data from any location with web access; no specific type of 
computer or operating system is required, as long as the unit has a current version of a web 
browser such as Netscape or Internet Explorer which allow secure encrypted data transmission.  
Before actual data transmission begins, the data management staff will help each site determine if 
the current web browser and location with respect to the firewall will work for data entry. 
 
The data management group will maintain a web site for this project consisting of public and 
personnel only components.  The web link will take the user to the log-on page for the study. 
Person-specific log-on names and passwords will be implemented.  Once a user has logged on to 
the site, the home page will be displayed.  The home page lists all of the categories under which 
documents are stored including: Protocols, Meeting Minutes, Questions and Answers, News and 
Events, Reports, Presentations, and Publications. 
 
Extensive edits will be done at the time of data entry and uploads, and the data discrepancy 
correction system will track changes made to the database.  Database edit checking programs will 
check for the completeness of each form, check for validity between forms, and check whether 
these data were collected and key-entered in the study protocol’s prescribed time frame.  At the 
time of initial data entry, data items on the web-based forms will be checked for valid codes, dates 
and value ranges at the hospital site browser level. The SNOMED data naming conventions will be 
followed for standardized coding.   
 
Data access and security rules will be established for all study personnel. Privileges will be 
granted as needed to study personnel to create database objects, enter data, search data, create 
reports, export data or print the data dictionary. Only authorized persons from each project will load 
data into the central database using the web-interface.  All data will be maintained in a database 
that is fully compliant with Emory University’s HIPAA policy and is subject to audit by the University 
Compliance Office. Quality control is the responsibility of all investigators and staff. This covers all 
phases of the projects, from building good data collection instruments and procedures, to training, 
and monitoring for adherence to the protocol timeline and visit schedules.  
 
11. STATISTICAL METHODS AND DATA ANALYSIS 
 
Primary Objective: 
The null hypothesis of interest is that chronic treatment with sitagliptin in CF subjects with 
high risk prediabetes does not change the rate of conversion to diabetes compared to CF subjects 


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not treated with sitagliptin. The primary outcomes of interest are the rate of conversion to diabetes 
and the time to conversion to diabetes in CF subjects. We will first use statistical tests of inequality 
between population proportions to test the null hypothesis of interest. We will then treat the 
conversion to diabetes during the two year follow-up, if applicable as a binary variable and use 
logistic regression to evaluate the treatment effect on the rate of conversion adjusting for other 
potential confounders. Lastly we will use survival analysis to analyze the time to event outcome, 
that is, the time to conversion. The exact time of the conversion to diabetes for CF subjects in the 
trial will be only known to take place between two follow-up visits; therefore the time to event 
outcome of interest, that is, the time to conversion to diabetes, is a type of interval-censored data. 
Statistical method for interval censored data (46, 47) will be used to evaluate the treatment effect 
and adjust for other potential confounders. Potential confounders for our analyses include baseline 
lung function, gender, and the degree of impairment in glucose intolerance, and baseline nutritional 
status,  
 
Secondary Objective: 
The null hypotheses are that the treatment with sitagliptin in CF subjects with high risk 
prediabetes does not: 1) result in preservation of beta cell mass and function;  2) reduce basal or 
hyperglycemia-induced levels of lung oxidative stress and inflammation: and  3) slow the rate of 
progression of lung disease.   
The outcomes of interest for systemic oxidative stress and inflammation are baseline redox 
couples (GSH/GSSG and cysteine/cystine), baseline markers of oxidative stress (dROM and 
protein carbonyls), and baseline levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) as well 
as changes in these levels from baseline to the two hour time point on the OGTT. The outcomes of 
interest for lung oxidative status and inflammation are baseline redox couples (GSH/GSSG and 
cysteine/cystine) and baseline levels of pro-inflammatory cytokines (TNF, IL-6, and IL-8) as well 
as changes in these levels from baseline to the two hour time point on the OGTT. The outcomes of 
interest for progression of lung disease are the rate of decline in lung function (FEV1.0) and the 
number of respiratory exacerbations requiring intravenous antibiotics. These outcome variables 
are measured at each 6 month follow-up visit (except lung function which is measured at every visit 
that is every three months) and hence are a type of repeated measurements. For each outcome 
measure, we will first conduct separate analyses at each follow-up visit using ANOVA for 
continuous outcomes and generalized linear models (48) for other types of outcomes, and then 
across all follow-up visits using generalized estimating equations (GEE) (49), which takes into 
account the correlation between observations from same subjects and are robust to miss-
specification of the covariance matrix. In addition, GEE modeling allows us to examine the effect of 
treatment across time on the outcomes of interest and adjust for other potential confounders, such 
as baseline lung function, gender, the degree of impairment in glucose intolerance, and baseline 
nutritional status.   
 
Drop-outs and Missing data: 
Descriptive data analysis will be conducted to summarize the study populations and detect 
potential selection bias due to dropouts and missing values. Based on previous experience, the 
primary reasons for dropouts are expected to be time constraints because of work and family 
making continued adherence to the protocol difficult, rapid progression of lung disease in those 
with more severe disease and thus the need to evaluate for transplant and withdraw from the 
study, and relocation to another city/state. Hence, the assumption of missing at random is valid 
(50). To account for drop-outs and missing data, we will use weighted survival analysis and GEE 
methods (51-53). 


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Sample size calculation/power analysis:  
            All sample size calculations were performed using PASS, commercial software for power 
calculations. Where possible, sample size calculations were based on the results obtained in previous 
studies in individuals with high risk prediabetes (7,8). 
            The primary outcome variable is the conversion from high risk prediabetes to overt CFRD. Forty 
percent of CF patients in the study age range are expected to have high risk prediabetes (54). We assume 
from analyses of the natural history of glucose intolerance, that CF subjects with high risk prediabetes are 
the pool of patients from which CFRD develops: few will transition directly from normal glucose tolerance to 
diabetes. We can estimate the annual rate of development of CFRD in this group with high risk prediabetes 
from the incidence of CFRD which is reported to be 9.3% of CF subjects over 20 years of age will develop 
CFRD per year (13, 55). Thus, assuming CFRD develops in the CF patients with high risk prediabetes, we 
calculate that 23% of the CF adults with high risk prediabetes will develop CFRD each year (i.e. incidence 
of CFRD in all CF adults, 9.3%, divided by fraction of CF adults with prediabetes, 0.40). Hence, for our 
sample size calculation, we assume that 20% of the CF adults with high risk prediabetes will develop CFRD 
each year, which is a conservative estimate. We propose to show that use of sitagliptin will have an effect 
size similar to that shown in treatment of type 2 DM. For example, the effect size in type 2 DM was 0.4 with 
metformin, 0.58 with life style changes, and 0.65 with TZD (13). The effect with pharmacologic agents was 
lower when the studies were repeated after washout (13). For this study, we are proposing that sitagliptin 
will have an effect size in the range of that seen for various treatment modalities used in type 2 DM. In 
addition, our preliminary data showed that 3 out of 24 participants (12 in the control group and 12 in the 
treatment group) who were followed for a minimum of 12 months converted to diabetes within 12 months. If 
all three conversions were in the control group, then the one-year conversion rate is 25% in the control 
group and 0% in the treatment group; if two conversions were in the control group, then the one-year 
conversion rate is 17% in the control group and 8% in the treatment group. We assume that the one-year 
conversion rate is between 17% and 25% in the control group and between 2% and 8% in the treatment 
group. Our preliminary data also showed that 2 out of 26 enrolled patients withdrew before 12 months, a 
dropout rate of 8%. 
The sample sizes are equal in the two treatment groups. Table 1 presents the total sample sizes 
required to achieve 80% power when a log-rank test is used to compare the two groups with a one-year 
follow-up, assuming an 8% dropout rate. Particularly, a total sample size of n=118 will achieve 80% power 
to detect the difference between a conversion rate of 5% (or 2%) in the treatment group and a conversion 
rate of 25% (or 20%) within a one-year follow-up. 
 
Table 1: Total sample size (n) required to achieve 80% of power with a significance level of 0.05, assuming 
an 8% dropout rate in 12 months. 
One-year conversion 
rate in the control 
group  
One-year conversion rate in the treatment group 
2% 
5% 
8% 
25% 
n=84 
n=118 
n=172 
20% 
n=112 
n=176 
n=294 
17% 
n=140 
n=242 
n=470 
 
            For the secondary objective, there is very little preliminary data to base a power analysis due to the 
novel and exploratory nature of the proposed study. Our sample size calculation showed that a total sample 
size of 114 achieves 80% power to detect an effect size of 0.544 or greater with a significance level of 0.05 
using a simple two-sample t-test at each visit. We expect the treatment effect to become more pronounced 
as the trial progresses. Thus, in a repeated measurement GEE analysis, adjusting for positive correlation 
between measurements at different visits from same individuals and other significant confounders is 
expected to increase the power for detecting a similar effect size compared to a simple t-test at each visit. 
 
 


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