Low-Carbohydrate Dietary Pattern on Glycemic Outcomes Trial
Phase: NA
Conditions: Diabetes, PreDiabetes, Metabolic Disease, Hyperglycemia, Diet Modification, Glucose Intolerance, Glucose Metabolism Disorders (Including Diabetes Mellitus), Endocrine System Diseases
Sponsor: Tulane University School of Public Health and Tropical Medicine

 
 
 
 
 
 
 
 
 
 
 
 
 
 
Low-Carbohydrate Dietary Pattern on 
Glycemic Outcomes Trial 
 
PROTOCOL 
 
 
 
 
 
 
 
 
 
 
 
PROTOCOL VERSION 2.2 
Dated: September 14, 2020 
New Orleans, LA 
 
 

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Table of Contents 
1. Overview ................................................................................................................................... 5 
2. Background and Significance ................................................................................................ 6 
2.A. Type 2 Diabetes Mellitus is a major global public health challenge ........................ 6 
2.B. Prediabetes is a major risk factor for cardiometabolic diseases .............................. 6 
2.C. Role of lifestyle in preventing diabetes ......................................................................... 6 
2.D. Low-to-moderate carbohydrate diets, weight loss, and cardiometabolic diseases 7 
2.E.  Mediterranean-style diet is associated with reduced risk of T2D and improved 
glycemic control ........................................................................................................................ 8 
2.F. Evidence for low-carbohydrate diets that emphasize Mediterranean-style dietary 
components ............................................................................................................................... 8 
2.G. Evidence for specific food groups and risk of T2D ..................................................... 8 
2.H. Gut microbiota, diet and T2D ......................................................................................... 9 
2.I. Continuous Glucose Monitoring ...................................................................................... 9 
2.I. Clinical and public health significance of the proposed study .................................... 9 
2.J. Innovation......................................................................................................................... 10 
3. Preliminary Studies ................................................................................................................ 10 
3.A. Summary of aggregate experience of the research team ....................................... 10 
3.B. Low-carbohydrate behavioral dietary intervention trial experience ........................ 11 
3.C. Other dietary intervention trial experience ................................................................. 11 
4. Study Design and Organization ........................................................................................... 12 
 4.A. Overview of trial design ................................................................................................ 12 
4.B. Study outcomes .............................................................................................................. 13 
4.B.1. Primary outcome ................................................................................................................ 13 
4.B.2. Secondary outcomes ........................................................................................................ 13 
4.C Study Timeline ................................................................................................................. 13 
6. Study Participants .................................................................................................................. 13 
6.A. Eligibility criteria .............................................................................................................. 13 
7. Recruitment and Randomization ......................................................................................... 14 
7.A. Recruitment ..................................................................................................................... 14 
7.A.1. Mass mailing, placement of brochures/flyers in community, TV/radio/billboard 
advertisements ............................................................................................................................... 15 
7.A.2. Database searches and targeted mailing..................................................................... 15 
7.A.3. Referrals and Local Partnerships .................................................................................. 15 
7.B. Randomization ................................................................................................................ 15 

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7.C. Masking ........................................................................................................................... 15 
7.D. Safety Considerations ................................................................................................... 16 
8. Dietary Intervention Program ............................................................................................... 16 
8.A. Low-carbohydrate dietary intervention group ............................................................ 16 
8.B. Usual Diet Group ............................................................................................................ 17 
8.C. Physical Activity ............................................................................................................. 17 
8.D. Dietary Adherence ......................................................................................................... 17 
9. Safety of Dietary Intervention .............................................................................................. 18 
10. Data Collection ..................................................................................................................... 18 
10.A. Study visits .................................................................................................................... 18 
10.A.1. Screening/baseline visits ............................................................................................... 19 
10.A.2. Follow-up visits and final visit ...................................................................................... 20 
10.A.3. CGM 6-month visit ........................................................................................................... 20 
10.B Study measurements ................................................................................................... 21 
10.B.1. Questionnaires ................................................................................................................. 21 
10.B.2. Dietary measurements .................................................................................................... 21 
10.B.3. Assessment and management of adverse effects .................................................. 21 
10.B.4. BP and anthropometric measures ............................................................................... 21 
10.B.5. Blood samples .................................................................................................................. 21 
10.B.6. Urine collection ................................................................................................................. 22 
10.B.7. Stool Specimen Collection ............................................................................................ 22 
10.B.8. CGM at 6 months: ............................................................................................................ 23 
11. Quality Assurance and Quality Control ............................................................................ 23 
11.A. Manual of procedures ................................................................................................. 23 
11.B. Training and certification ............................................................................................ 23 
12. Sample Size and Statistical Power ................................................................................... 23 
13. Data Management and Analysis ....................................................................................... 24 
13.A. Data management ....................................................................................................... 24 
13.B. Data analysis plan ....................................................................................................... 24 
13.B.1. Exploratory data analysis .............................................................................................. 24 
13.B.2. Primary, secondary, and exploratory outcomes ..................................................... 24 
15. Anticipated Challenges ....................................................................................................... 25 
16. Protection of Human Subjects ........................................................................................... 25 

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16.A. Protection of human subjects from research risks ................................................. 25 
16.A.1. Risks to the subjects ....................................................................................................... 26 
16.A.2. Adequacy of protection against risks......................................................................... 27 
16.A.3. Potential benefits of the proposed research to human subjects and others ... 28 
16.A.4. Importance of knowledge to be gained ...................................................................... 28 
16.A.5. Remuneration .................................................................................................................... 29 
16.B. Data safety and monitoring plan ................................................................................ 29 
Bibliography and References Cited ......................................................................................... 31 
 
 
 
 
 

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1. Overview 
The increasing prevalence of type 2 diabetes mellitus (T2D), a major cause of morbidity and 
mortality worldwide, is a critical public health concern. In the United States, an estimated 33.9% 
of adults have prediabetes (impaired fasting glucose, elevated hemoglobin A1c (HbA1c), or 
impaired glucose tolerance). Individuals with prediabetes are at elevated risk of T2D and 
cardiovascular disease (CVD), with 5–10% developing clinical T2D each year.  
In the short-term, among patients with T2D, low-to-moderate carbohydrate diets (energy 
percentage below 45) have a greater glucose-lowering effect than do high-carbohydrate diets, 
with larger glucose-lowering effect the greater the carbohydrate reduction. Additionally, 
compared with low-fat diets, Mediterranean diets that are high in unsaturated fats (particularly 
cis-monounsaturated fats) reduce risk of T2D and CVD and improve glycemic control among 
diabetics. However, compared with usual diets, the effect of a behavioral intervention promoting 
a low-carbohydrate/high-unsaturated fat and protein dietary pattern that emphasizes 
consumption of non-starchy vegetables, plant-based oils, fish, poultry, and mixed nuts on 
glucose homeostasis, and other metabolic risk factors among individuals with prediabetes or 
early-stage untreated T2D is not well understood.  
Our long-term goal is to develop and implement dietary intervention(s) that reduce risk of 
T2D. The overall goal of this randomized controlled trial is to study the effect of a behavioral 
intervention promoting a low-carbohydrate/high-unsaturated fat and high-protein dietary pattern 
(initial target <40 g digestible carbohydrates, final target <60 g digestible carbohydrates) 
compared with a usual diet on metabolic risk factors among individuals with prediabetes or 
early-stage untreated diabetes (HbA1c 6.0–6.9%). Specifically, we will test the following 
hypotheses: 
Primary hypothesis: Compared with usual diet, over a 6-month period, a healthy low-
carbohydrate/high unsaturated fat and high-protein dietary pattern will lead to a larger decrease 
of HbA1c, by at least 0.15%. 
Secondary hypothesis: Over a 6-month period, a healthy low-carbohydrate/high-unsaturated 
fat and high-protein dietary pattern will lead to larger improvements in the following major 
secondary outcomes: fasting glucose, systolic blood pressure (BP), total-to-HDL-cholesterol 
ratio, and body weight.  
Exploratory outcomes: We will also study the effect of the intervention on the 6-month change 
in: insulin and homeostasis model assessment of insulin resistance (HOMA-IR); diastolic BP; 
waist circumference; and estimated CVD risk.  
To achieve these study aims, we will recruit 150 adults with prediabetes or untreated 
diabetes (HbA1c 6.0–6.9%) in the Greater New Orleans, LA area. Using a stratified, blocked 
randomization scheme, participants will be assigned to either a behavioral modification 
intervention aimed at promoting a healthy low-carbohydrate dietary pattern or to usual diet. The 
intervention group will have an intensive phase for 3 months, followed by a maintenance phase 
in months 4 through 6. The primary outcome will be difference between the active intervention 
and control groups in the change in HbA1c from baseline to 6 months of follow-up. We expect 
80% power to detect a difference of at least 0.15% in change of HbA1c. Changes in other 
metabolic risk factors will be studied concurrently. Metabolic risk factors will be assessed at 
baseline, 3 months, and 6 months of follow-up. 
There is much interest regarding dietary approaches to prevent T2D and its complications. 
The results from this study will help to determine whether, compared with usual diet, a 
behavioral intervention aimed at promoting a healthy low-carbohydrate dietary pattern improves 
metabolic risk factors. 
 
 

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2. Background and Significance 
2.A. Type 2 Diabetes Mellitus is a major global public health challenge 
Diabetes is a strong and independent risk factor for CVD morbidity and mortality. A meta-
analysis of 102 prospective studies (698,782 participants) estimated diabetes leads to an 
approximately 2-fold increased risk in vascular diseases, including coronary heart disease 
(CHD) and major stroke subtypes, and deaths due to other vascular causes.1 Among 
participants with diabetes, CHD risk is about 50% higher among those with fasting blood 
glucose ≥7 mmol/L compared with those with fasting blood glucose <7 mmol/L.1  In addition to 
increasing CVD risk, diabetes can cause diabetic retinopathy,2 chronic kidney disease,3 lower 
limb amputation,4 and other complications. Most individuals with diabetes have T2D.5 The US 
Centers for Disease Control and Prevention (CDC) estimated that 30.2 million adults ≥18 years 
(12.2%) had diabetes in 2015, with 7.2 million (23.8%) not being aware of or reporting 
diabetes.5 Diagnosed diabetes prevalence among US adults has increased substantially over 
time, from 2.54% in 1980 to 7.40% in 2015.6 Diabetes prevalence is also high globally, with an 
estimated 2014 age-standardized prevalence of 9.0% in men and 7.9% in women.7 Diabetes 
accounts for an increasing portion of US healthcare expenditures. Total cost of diagnosed 
diabetes in the US was estimated to be $245 billion in 2012, 41% higher than in 2007.8 Diabetes 
is associated with much higher lifetime medical expenses, with higher expenses for those 
diagnosed at younger ages.9 
2.B. Prediabetes is a major risk factor for cardiometabolic diseases  
Prediabetes, defined by the American Diabetes Association (ADA) as impaired fasting 
glucose (IFG), impaired glucose tolerance (IGT), or elevated HbA1c, is also referred to as 
“intermediate hyperglycemia”10 and “high-risk state of developing diabetes”.11 The ADA defines 
prediabetes as having: fasting plasma glucose of 100–125 mg/dL (IFG); 2-hour post-load 
glucose in the 75-g oral glucose tolerance test (OGTT) of 140–199 mg/dL (IGT); or HbA1c 5.7–
6.4%.12 Prediabetes itself is not a disease; for all three tests, “risk is continuous, extending 
below the lower limit of the range and becoming disproportionately greater at the higher end of 
the range”.12 The CDC estimated that in 2015, 33.9% of US adults had prediabetes based on 
fasting glucose or HbA1c.5 Among those with prediabetes, only 11.9% reported having being 
told this by a medical professional.5 Approximately 5–10% of individuals with prediabetes 
develop diabetes within one year, depending on how prediabetes is defined.13 In a meta-
analysis, annual diabetes incidence was 15–19% among individuals with both IFG and IGT, 
while it was 4–6% in those with isolated IFG and 6–9% in those with isolated IGT.13  
A recent meta-analysis (1,611,339 participants from 53 studies) reported that prediabetes as 
defined by the ADA is associated with higher risk of composite CVD events and CHD.14 IFG and 
IGT were also positively associated with increased risk of stroke and all-cause mortality.14 
Prediabetes is linked with increased risk of other conditions typically thought of as diabetes 
complications, such as neuropathies and nephropathies.15 Importantly, it is possible for 
individuals with prediabetes to revert to normoglycemia, as observed in observational studies13 
and lifestyle or drug intervention trials.16,17 In the Diabetes Prevention Program (DPP), reversion 
to normoglycemia was associated with lower long-term T2D risk18 and lower predicted CVD 
risk.19 
2.C. Role of lifestyle in preventing diabetes 
Much evidence from observational studies and clinical trials supports the critical role of diet 
and other lifestyle factors in preventing T2D. Globally, lifestyle transitions towards reduced 
physical activity, increased consumption of refined carbohydrates, coupled with resulting 
changes in body composition, has led to increases in diabetes prevalence and severity.20 Body 

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mass index (BMI), waist circumference, and waist-to-height ratio are predictors of T2D.21 The 
DPP, which combined calorie restriction and exercise to promote weight loss, substantially 
reduced risk of T2D (by 58%) among individuals with elevated FPG and IGT;22 a benefit that 
persisted in 10-year follow-up analyses.16 Other trials of lifestyle modification focused on diet 
and exercise have also shown benefits in study populations in China,23 Finland,24 and India.25  
2.D. Low-to-moderate carbohydrate diets, weight loss, and cardiometabolic 
diseases 
Low-to-moderate carbohydrate diets (<45% of energy from carbohydrates) are popular 
dietary approaches for losing weight. Weight loss is a key component of the DPP lifestyle 
intervention26 and ADA lifestyle recommendations.12,27 Meta-analyses from our group28 and 
others support that low-to-moderate carbohydrate diets are at least as effective as low-fat diets 
at promoting weight loss. For instance, a meta-analysis reported a 2-kg (95% CI, 3.1–0.9) larger 
weight loss in low-carbohydrate diet (<120 g carbohydrates/day) arms compared with low-fat 
diet (<30% energy from fat) arms.29 Estimated 10-year CVD risk was lower in low-carbohydrate 
than low-fat arms.29 This aligns with research published by our team; in a 12-month trial of 
participants with obesity, a low-carbohydrate diet (target <40 g carbohydrates/day) was more 
effective than a low-fat diet (target <30% energy from fat, <7% saturated fat) for weight loss and 
CVD risk factor reduction.30  
Low-to-moderate carbohydrate diets may also be beneficial among patients with T2D. Low-
carbohydrate diets have come in and out of favor as treatment of diabetes.31 In a meta-analysis 
(1376 patients;10 trials), after 3 or 6 months of the intervention, low-to-moderate carbohydrate 
diets (<45% energy from carbohydrates) led to a 0.34% lower HbA1c (95% CI, 0.06–0.63%) 
compared with high-carbohydrate diets.32 Compared with high-carbohydrate diets, there was a 
greater reduction in HbA1c the greater the reported carbohydrate restriction.32 There was no 
benefit of the low-to-moderate carbohydrate diets on HbA1c at 12 months or longer, and no 
difference between interventions on BMI, body weight, low-density lipoprotein (LDL) cholesterol 
or quality of life.32 However, results may have been affected by dietary adherence or glucose 
medication. There was evidence of diabetes medication reduction in the low-carbohydrate arms 
in some studies,33–37 with evidence of medication reduction and improved blood glucose stability 
persisting for up to 2 years.38 Hypoglycemia (though not after medication adjustment) was 
observed in three subjects taking insulin or a sulfonylurea out of twelve subjects in the low-
carbohydrate arm of another study.39 In a subset of participants with T2D (n=46) from a large 
weight loss trial, compared with those randomized to a low-fat diet and orlistat, those 
randomized to a low-carbohydrate diet for 48 weeks had improved HbA1c (0.8% lower, 95% CI, 
-1.5, -0.02%) and a reduction in antiglycemic medications, despite similar weight loss effects of 
the interventions.40 
Though low-to-moderate carbohydrate diets have been studied among overweight and 
obese participants (primarily focused on weight loss), less is understood about the effects of 
such diets on glycemic outcomes specifically among individuals with prediabetes. A study 
among participants with IGT observed a reduction at 12 months in weight, HbA1c, and other 
glycemic outcomes among individuals who participated in a 7-day in-hospital education 
program, though this was not randomized.41 A randomized pilot trial of overweight or obese 
individuals with T2D or prediabetes found that, over 3 months and at 12 months, a very low-
carbohydrate diet improved HbA1c, led to higher medication discontinuation, and more weight 
loss compared with a low-fat diet.34,37 However, only 4 individuals had prediabetes. Given 
benefits of low-to-moderate carbohydrate diets for weight loss in general populations and for 
glycemic control among patients with T2D, further study of these diets are warranted among 
individuals with prediabetes who are at elevated cardiometabolic disease risk. 

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2.E.  Mediterranean-style diet is associated with reduced risk of T2D and 
improved glycemic control  
Though there is no one “Mediterranean diet”, the Mediterranean dietary pattern tends to 
have the following characteristics: high consumption of vegetables, fruits, breads and cereals, 
legumes, nuts and seeds; low-to-moderate consumption of dairy products, fish, poultry and 
eggs; little consumption of red meat and sweets; and red wine in moderation.42 Olive oil is an 
important source of fat. In many observational studies, adherence to the Mediterranean-style 
dietary pattern is associated with reduced risk of CVD43 and T2D.44,45 Evidence from 
randomized trials also supports the benefits of this dietary pattern. In several trials, participants 
randomized to Mediterranean diets had substantially lower risk of CVD than those randomized 
to low-fat control diets.46,47 In the three-arm randomized PREDIMED trial of participants at high 
risk of CVD, after 4.1 years of follow-up, those randomized to a traditional Mediterranean diet 
supplemented with either olive oil or nuts had a 30% reduced risk of T2D compared to those in 
the low-fat control diet group.48 In all PREDIMED arms, average carbohydrate intake was 
relatively low (39.7–43.7% at end of trial).47 Two trials have found a higher rate of remission 
from metabolic syndrome among individuals randomized to a Mediterranean diet compared with 
those randomized to control diets (prudent or low-fat) during 2–5 years of follow-up.49,50 The 
Mediterranean pattern may also be beneficial among individuals with T2D. Meta-analyses have 
reported that, among patients with T2D, those randomized to a Mediterranean diet had lower 
HbA1c levels and CVD risk factors, and more significant weight loss, compared with those 
randomized to control diets.51  
2.F. Evidence for low-carbohydrate diets that emphasize Mediterranean-style 
dietary components 
Many low-carbohydrate diets involve increased consumption of food items, such as red 
meat,52 that are associated with increased cardiometabolic disease risk. However, low-
carbohydrate dietary approaches can focus on substituting carbohydrates with foods common in 
Mediterranean-style diets, such as olive oil and nuts, which may improve cardiometabolic 
health. In a 4-year Italian study of individuals with newly diagnosed T2D, those randomized to a 
low-carbohydrate Mediterranean diet (<50% carbohydrates; consumed ~44%) had more 
favorable changes in glycemic control, higher rates of T2D remission, and delayed need for 
antiglycemic drugs compared with participants randomized to a low-fat diet (<30% fat, <10% 
saturated fat).53,54 A 12-month Israeli study assessed low-carbohydrate Mediterranean (35% 
carbohydrates), traditional Mediterranean, and ADA (both 50–55% carbohydrates) diets in 259 
overweight participants with T2D.55 Most CVD risk factors improved in all groups; there was only 
HDL improvement in the low-carbohydrate Mediterranean diet and this diet was superior to the 
other diets in improving glycemic control.55 In a 2-year weight-loss study of moderately obese 
participants, low-carbohydrate and Mediterranean diets were superior to low-fat diet for weight 
loss.56 Participants in the low-carbohydrate arm were counseled to choose vegetarian sources 
of fat and protein and to avoid trans fat. At 6 years after study commencement, despite weight 
regain, there were still long-term benefits, particularly for the low-carbohydrate and 
Mediterranean diets.57 In whole, evidence supports that low-carbohydrate Mediterranean-style 
diets are feasible and may have metabolic benefits. 
2.G. Evidence for specific food groups and risk of T2D 
Prospective cohort studies have found consumption of specific foods and beverages is 
associated with diabetes risk. Meta-analyses report higher consumption of processed and 
unprocessed red meat,58 white rice (particularly in Asian populations),59 and sugar-sweetened 
beverages60,61 are associated with higher T2D risk. Consumption of green leafy vegetables,62,63 
yogurt,64 whole grains,65 decaffeinated and total coffee,66 and light-to-moderate alcohol 

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consumption67 are associated with reduced risk. Consumption of fruits, particularly blueberries, 
grapes, and apples, are associated with reduced risk; fruit juice is associated with higher risk.68 
2.H. Gut microbiota, diet and T2D 
There is increasing evidence for the importance of gut microbiota in risk of type 2 diabetes 
and other cardiometabolic diseases.69 Additionally, dietary modifications, including changes in 
carbohydrate consumption, can lead to substantial changes in gut microbiome over short 
periods of time.70,71 Less is known about longer-term changes to the gut microbiota during the 
adoption of a low-carbohydrate diet and how these changes may influence cardiometabolic risk. 
We plan to collect stool specimens at baseline, 3 months, and at 6 months, for potential future 
studies on how this intervention affects the gut microbiome.  
 
2.I. Continuous Glucose Monitoring 
As HbA1c is a marker of weighted average glucose over the past 8 to 12 weeks, it does not 
explicitly capture short-term glycemic excursions or variability. It has been theorized that such 
fluctuations may have an independent role in the development of diabetes complications.72 
Though more evidence is needed, research has found relationships of higher glycemic 
variability with coronary artery disease (CAD) and microvascular outcomes in type 2 diabetes 
(T2D).73,74 This suggests that improved control of extreme glucose excursions, particularly 
postprandially, may help to reduce risks of such complications.74 
In one study of a low-calorie, low-carbohydrate diet compared with a low-calorie, low-fat 
behavioral dietary intervention among individuals with T2D, there was evidence that some 
markers of glycemic variability were further reduced in the low-carbohydrate arm compared with 
the low-fat arm (assessed by 48-hour continuous glucose monitoring) at 6 months, 1 year, and 2 
years.35,38,75  However, there is not prior work assessing how a behavioral intervention aimed at 
reducing carbohydrate consumption affects mean glucose, glucose exposure above the set-
point of 100 mg/dL, glucose excursions, or glycemic variability as measured by continuous 
glucose monitoring among individuals with untreated T2D or at high risk of T2D.  
Given this background, we will use continuous glucose monitors (CGM) to collect data for up 
to 14 days on glucose levels at the end of the 6-months study and will compare mean 24-h 
glucose among those in the intervention group compared with mean 24-h glucose among those 
in the control group. We will also measure other markers of glycemic exposure, such as 
glycemic variability (mean amplitude of glycemic excursions (MAGE), standard deviation of 
glucose, coefficient of variation) and mean 24-hour glucose during wake-time (6:00 AM to 12:00 
AM), and during sleep-time (12:00 AM to 6:00 AM). 
 
2.I. Clinical and public health significance of the proposed study 
Prediabetes, or intermediate hyperglycemia, is a marker of high risk of developing T2D and 
other complications. Due to increasing prevalence of T2D and associated morbidity and 
mortality globally, a better understanding of dietary approaches to delay progression to T2D or 
to promote reversion to normoglycemia is a high public health priority. This study proposes to 
assess the effect of a behavioral intervention promoting a low-carbohydrate/high-unsaturated fat 
dietary pattern (initial target <40 g digestible carbohydrates, final target <60 g digestible 
carbohydrates) on HbA1c, a marker of glycemic control, and other metabolic risk factors. 
Building from prior findings from clinical and observational studies, we will develop a dietary 
intervention that promotes the consumption of non-starchy vegetables, plant-based oils, fish, 
poultry, and mixed nuts, that are thought to reduced risk of T2D or CVD. Participants assigned  

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to the intervention will be trained in behavioral techniques that will provide capacity to 
maintain dietary changes long after study completion. Our outcome measures will assess the 
effect of this dietary intervention in a “real-life” setting as opposed to dietary modifications 
achieved in metabolic ward studies or through food prepared in research kitchens. Findings 
from this study may provide evidence in support of promoting alternative dietary styles among 
individuals with high T2D and CVD risk and could potentially be used to inform dietary 
interventions used in programs like DPP.  
2.J. Innovation 
The status quo as it pertains to dietary approaches for reducing risk of T2D is focused on 
reducing caloric intake and total fat intake. However, recent evidence suggests that the types of 
fat, rather than the quantity of fats may be more important, with evidence supporting that a 
Mediterranean-style diet that does not restrict fat intake reduces risk of developing both T2D48 
and CVD47. Moreover, in the short-term, low-carbohydrate diets, which are popular weight loss 
diets, have a greater glucose-lowering effect than do high-carbohydrate diets among patients 
with T2D.32 However, the effect of low-carbohydrate diets that emphasize consumption of non-
starchy vegetables, plant-based oils, fish, poultry, and mixed nuts on T2D prevention is unclear, 
particularly compared with higher-carbohydrate diets more commonly consumed in the US. The 
proposed research is innovative, in our opinion, because it represents a substantial departure 
from the status quo by assessing the combined effect of a low-carbohydrate, high unsaturated 
fat and protein diet on cardiometabolic risk factors among adults with prediabetes or early-stage 
untreated diabetes. We expect the results from this study have the potential to lead to new 
horizons for developing and implementing dietary approaches (other than the most commonly 
used reduced fat diet) that will substantially reduce risk of cardiometabolic disease among 
adults with T2D or at high risk of T2D. The proposed intervention dietary approach promotes 
consumption of dietary components thought to reduce risk of cardiometabolic disease and the 
behavior change intervention has expected applicability in clinical practice. 
 
3. Preliminary Studies 
3.A. Summary of aggregate experience of the research team 
Dr. Kirsten Dorans is trained in cardiovascular disease epidemiology, with strong training in 
epidemiologic methods and biostatistics. Her publication record includes studies of behavioral 
risk factors and risk of chronic disease. She has published on the relationships between dietary 
intake and chronic heart failure76,77 and on physical activity and incident multiple sclerosis78. She 
served as lead author, conducting data management, analysis, drafting, and revision of two of 
these manuscripts. In graduate school, she focused on studying links between outdoor air 
pollution and chronic diseases and has published several papers in this field. The COBRE 
program will provide an excellent opportunity for the JFI to transition from air pollution research 
to clinical and translational research focused on nutrition and diabetes. Building off of her 
training in observational epidemiology, this program will involve training and practical 
experience that will allow her to broaden her expertise and to develop practical skills for carrying 
out clinical research.   
The mentorship team has much experience and prior successful collaborations in key areas 
related to this study. Dr. Jiang He is an internationally renowned expert in cardiometabolic 
disease clinical and epidemiological research. He has served as PI for many epidemiological 
studies and clinical trials, including clinical and observational studies focused on dietary 
consumption and chronic diseases79–84 and has conducted extensive global research on 
diabetes.85,86 Dr. Bazzano has collaborated extensively with Dr. He for more than 15 years in 
research related to diet and chronic disease. She is a clinical investigator and has expertise in 

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nutritional epidemiology and clinical research. Dr. Bazzano was the PI of a highly successful 
clinical trial comparing the effects of low-carbohydrate and low-fat diets on weight and 
cardiovascular risk factors among individuals with obesity, which was a subproject within the 
Tulane COBRE in Hypertension and Renal Biology.30 Dr. He served as Dr. Bazzano’s mentor 
for this clinical trial. They have collaborated on much other work related to dietary and chronic 
disease, including a meta-analysis on low-carbohydrate diets.28 Dr. Bazzano has also published 
many articles on diet and risk of diabetes87,88 and on diabetes in the Bogalusa Heart Study.89–91  
3.B. Low-carbohydrate behavioral dietary intervention trial experience  
In the study on macronutrient composition of diet and risk factors for cardiovascular disease 
(MACRO) study, 148 individuals without clinical cardiovascular disease or diabetes and with 
obesity were randomly assigned to a low-carbohydrate or a low-fat behavioral dietary 
intervention for 12 months. In the low-carbohydrate arm, daily dietary intake of carbohydrates 
decreased from an average of 242 g at baseline to 97 g, 93 g, and 127 g at 3, 6, and 12 
months, respectively. At 12 months, participants in the low-carbohydrate intervention group had 
greater decreases in weight (-3.5 kg; 95% CI, -5.6 to -1.4 kg) and fat mass (-1.5%; 95% CI, -
2.6% to -0.4%) and greater improvement in several cardiovascular risk factors.30 This suggests 
that restricting carbohydrates may be an option for weight loss and reduction of cardiovascular 
risk factors. Further analyses found that the low-carbohydrate dietary intervention led to similar 
or greater improvement in inflammation, adipocyte dysfunction, and endothelial dysfunction 
compared with the low-fat dietary intervention92 and that the low-fat diet reduced peptide YY 
more than the low-carbohydrate diet, suggesting satiety may be better preserved on low-
carbohydrate diets.93 No serious adverse events were reported in this study and the number of 
participants with symptoms were similar between the two diets, with the exception of more 
participants having headaches on the low-fat diet at 3 months (18 vs 6 participants, p = 0.03).30 
Dr. Bazzano served as PI for this study and Dr. He served as her mentor. Dr. Bazzano 
mentored one of her PhD students in conducting analyses and writing and editing manuscripts 
related to this project. 
3.C. Other dietary intervention trial experience 
Dr. He has also led or been involved with many dietary intervention trials, including both 
behavioral change and feeding study interventions. In the Protein and Blood Pressure (ProBP) 
study, 352 adults with prehypertension or stage 1 hypertension in New Orleans, LA and 
Jackson, MS were assigned to take, in a random order, 40 g/d soy protein, milk protein, or 
carbohydrate supplementation each for 8 weeks. Compared with the high-glycemic index 
refined carbohydrate, both soy protein and milk protein supplementation were associated with a 
-2.0 mm Hg (95% CI -3.2 to -0.7 mm Hg) and -2.3 mm Hg (-3.7 to -1.0 mm Hg) net change in 
systolic blood pressure.84 These findings suggest that partial replacement of carbohydrate with 
soy or milk protein might be an important part of nutrition intervention strategies to prevent and 
treat hypertension. Additionally, soy protein supplementation led to reduction in plasma E-
selectin compared with carbohydrate and milk protein and in plasma leptin compared with 
carbohydrate.94 Soy protein also led to improvement in lipid profile compared with carbohydrate 
and milk protein.95 Dr. He was PI for this project. 
In the Fiber Intervention on Blood Pressure (FIBRE) study, 110 participants ages 30–65 
years with untreated pre-hypertension or stage-1 hypertension and serum cholesterol level < 
240 mg/dl were randomly assigned to 8-g/day of water soluble fiber from oat bran or a control 
intervention (double-blind RCT). Over the 12-week study period, net changes in systolic and 
diastolic blood pressure were -1.8 mm Hg (-4.3 to 0.8) and -1.2 mm Hg (-3.0 to 0.5 mm Hg), 
respectively.82 Net changes in total, HDL-, and LDL-cholesterol were -2.40 mg/dL (-10.60 to 

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5.81 mg/d:), -1.66 mg/dL (-4.55 to 1.22 mg/dL), and -1.33 mg/dl (-8.33 to 5.68 mg/dL), 
respectively.96 Dr He was PI for this study. 
Dr. He is currently serving as a mentor for Dr. Katherine Mills’ COBRE project (Effect of 
Dietary Sodium Reduction in Kidney Disease Patients with Albuminuria; SUPER). In this project, 
participants with chronic kidney disease and albuminuria are being randomized to a behavioral 
modification program designed to reduce dietary sodium intake to ≤2,300 mg/day or to usual 
care and test the effect of this intervention on change in albumin-to-creatinine ratio from 
baseline to 24-weeks.  
 
4. Study Design and Organization 
 4.A. Overview of trial design 
We propose to conduct a randomized controlled trial aimed 
at testing the effect of a behavioral intervention that promotes 
reduced carbohydrate intake and increased consumption of 
heart-healthy unsaturated fats and protein in patients with 
HbA1c 6.0–6.9% (Figure 1). We  plan to recruit 150 individuals 
with elevated HbA1c and randomly assign them to a 
moderately intensive intervention on diet pattern,97 using well-
established methods for behavioral modification, or to usual 
diet. We will compare the difference between the active 
intervention and control groups for change in HbA1c from 
baseline to 6 months of follow-up (primary outcome). We will 
assess four major secondary outcomes: fasting plasma 
glucose, systolic BP, total-to-HDL cholesterol ratio, and body weight. In addition, we will look at 
several other exploratory outcomes: insulin and HOMA-IR, diastolic BP, waist circumference, 
and estimated CVD risk, as estimated by the 2013 ACC/AHA risk equation. The main trial 
components are summarized in Table 1.  
Table 1. Study Overview 
Study Design 
Randomized controlled trial 
Study Participants 
150 participants with elevated HbA1c (6.0–6.9%) 
Intervention Group (n=75) Behavioral modification to reduce carbohydrate consumption and 
promote consumption of foods such as non-starchy vegetables, 
plant-based unsaturated oils, nuts and seeds, avocados, eggs, 
seafood, poultry, lean meat and tofu. We will recommend 
moderate consumption of cheese, unsweetened Greek yogurt, 
and low-carb milk. If consuming higher-carbohydrate items, 
recommend legumes, fruits, (limited) whole grains. Target <40 g 
net carbohydrates per day for first 3 months and will have a goal 
of <40 net g carbohydrates per day; <60 g net carbohydrates per 
day for months 4 onwards.  
Usual Diet Group (n=75) 
No dietary intervention. To encourage continued participation in 
the trial, we will offer optional monthly educational sessions on 
unrelated topics, such as retirement planning or health insurance 
Outcome Measures 
Primary: HbA1c; Secondary: fasting plasma glucose, systolic BP, 
total-to-HDL-cholesterol ratio, and body weight   

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4.B. Study outcomes 
4.B.1. Primary outcome: The primary outcome will be the difference between the intervention 
group and the usual diet group for change in HbA1c from baseline to 6 months. Changes in 
HbA1c will be calculated from blood samples taken at baseline and 6 months. 
4.B.2. Secondary outcomes: Secondary outcomes will include changes from baseline to 6 
months of fasting plasma glucose, systolic BP, total-to-HDL cholesterol ratio, and body weight.,  
4.B.3. Other outcomes: We will also study the effect of the intervention on the following 
outcomes: insulin and homeostasis model assessment of insulin resistance (HOMA-IR); 
diastolic BP; waist circumference; total-to-HDL-cholesterol ratio; and estimated CVD risk.  
4.C Study Timeline 
Table 2 shows 
the timeline, 
which will be 
followed in the 
implementation 
of study-
related 
activities, such 
as publications 
and 
submission of 
an R01 grant 
application. 
The first 6 months will focus on development of manual of operations (MOP), intervention 
program, study forms, study protocol, Institutional Review Board (IRB) approval, and pilot 
testing of the intervention program. It will also involve staff training and certification. During the 
last half of year 1, recruitment, intervention, and data collection will commence. During the last 3 
months of year 3, data quality control and analysis will be carried out. Throughout the study 
period, the JFI will publish peer-reviewed manuscripts from ongoing Tulane University research 
projects. 
6. Study Participants 
6.A. Eligibility criteria 
Inclusion criteria 
• 
Men or women ages 40 to 70 years: aim to recruit 50% women 
• 
Any race or ethnicity: aim to recruit 40% ethnic minorities (i.e., African American and 
Hispanic), close to population in the greater New Orleans area98 
• 
HbA1c 6.0–6.9% 
• 
Willing and able to provide informed consent 
Exclusion criteria 
• 
Diagnosed type 1 diabetes mellitus based on patient self-report 
• 
Use of agents affecting glycemic control (medications for diabetes, oral glucocorticoids) 
within the past three months prior to enrollment based on patient self-report 
• 
Medical condition in which low-carbohydrate diet may not be advised  
o Estimated glomerular filtration rate (eGFR) ≤45 mL/min/1.73 m², which is close to 
the 5th percentile of eGFR among non-diseased individuals of 70 years of age99  
Table 2. Study Timeline 
 
 
 
 
Year 1 
Year 2 
Year 3 
Develop MOP, intervention program, 
study forms, and pilot testing 
X 
X 
 
 
 
 
Certification and training of staff 
X 
 
 
 
 
 
Recruitment 
 
X 
X 
 
 
 
Intervention and data collection, 
measurement, entry, cleaning 
 
X 
X 
X 
X 
 
Data quality control and analysis 
 
 
 
 
 
X 
Publications 
X 
X 
X 
X 
X 
X 
R01 grant submissions, resubmissions 
 
 
 
X 
X 
X 

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o Self-report of liver disease due to hepatitis or alcohol; osteoporosis; untreated 
thyroid disease; gout; or cancer (other than non-melanoma skin cancer) requiring 
treatment in the past year, unless prognosis is excellent 
• 
Factors that may affect HbA1c:  
o Hemoglobin <11 mg/dL (cutpoint for moderate-to-severe anemia, which could 
lead to falsely elevated or lowered HbA1c)100   
o Recent blood donation or blood transfusion (self-report, past 4 months) 
o Human Immunodeficiency Virus (self-report)101 
• 
Self-reported history of intensive care unit stay due to Coronavirus Disease 2019 
(COVID-19) in the past three months, as severe COVID-19 may affect blood glucose 
levels 
• 
Allergies to nuts 
• 
For women, current pregnancy, breastfeeding, or plans to become pregnant during the 
study 
• 
Consumption of ≥21 alcoholic drinks per week or consumption of ≥6 drinks per occasion 
• 
For the CGM collection at the end of the study period only: known allergy to adhesives 
or other products involved with CGM use (e.g., skin disinfectants), current pregnancy, 
currently on hemodialysis or peritoneal dialysis, or people with other implanted medical 
devices (e.g., a pacemaker) 
• 
Current or planned residence making it difficult to meet trial requirements (due to 
distance from study site and/or challenges regularly traveling to site) 
• 
Current participation in another lifestyle intervention trial or a pharmaceutical trial 
• 
Participation of another household member in the study; employees or persons living 
with employees of the study 
• 
Other concerns regarding ability to meet trial requirements, at the discretion of the 
principal investigator or study coordinator 
 
7. Recruitment and Randomization 
7.A. Recruitment 
We will recruit study participants from the greater New Orleans area. The initial focus of our 
recruitment will be mass mailing of individuals in the greater New Orleans area and recruitment 
through placing flyers and brochures in the community. If community-based recruitment is not 
successful or cost-effective, we will recruit out-patients from the Ochsner Health System and 
Tulane Medical Center (TMC), from which our group has prior experience recruiting patients. 
For this recruitment, we will focus on electronic searches of medical records and laboratory 
databases. We will also carry out targeted solicitation of referrals from physicians who care for 
patients likely to meet our inclusion and exclusion criteria.  
In addition to this recruitment plan, we have several contingency plans: (1) extending 
recruitment to other medical centers in the New Orleans area, including the Veterans Affairs 
Medical Center (VAMC), East Jefferson General Hospital, and West Jefferson Medical Center, 
with whom Tulane has well-established relationships; (2) TV/radio advertisements; (3) arrange a 
news story about the study in local TV newscasts, radio talk programs, and/or print media; and 
(4) conduct outreach at local community events and churches. We have ample experience with 
each of these approaches.  
Based on U.S. Census Bureau 2016 population estimates, the metro New Orleans area 
population was approximately 35% African American or black and 9% Hispanic.98 Given our 
prior experience and population distribution in this region, we plan to recruit a distribution of 
study participants with 40% ethnic minorities. 

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7.A.1. Mass mailing, placement of brochures/flyers in community, TV/radio/billboard 
advertisements: Community recruitment approaches include: mass mailing individuals who live 
in the New Orleans area; brochures/flyers in the community; emailing the brochure; TV, radio, 
poster, or billboard advertisements in the New Orleans area. Interested individuals will be pre-
screened; those at elevated risk for prediabetes or T2D, i.e. individuals who are obese or 
overweight and/or have a sufficiently high score from the American Diabetes Association’s 
Diabetes Risk Assessment Questionnaire will be invited into the clinic for a screening visit. 
7.A.2. Database searches and targeted mailing: We will request IRB approval for a waiver for 
HIPAA authorization to conduct database searching and hospital chart reviews for identification 
of potentially eligible study participants. After identifying a potentially eligible patient, we will  
send this individual an invitation letter signed by the investigators and/or the individual’s 
personal physician and brochure via mail or email. Individuals who express interest in the study 
will have a pre-screening telephone interview for confirmation of potential eligibility. Those still 
interested and potentially eligible for enrollment will be scheduled for a visit at the COBRE study 
clinic.  
7.A.3. Referrals and Local Partnerships: In addition to local physician referrals, we will 
explore holding outreach community events in the New Orleans area. Local community partners 
may post information about the study on their social media platforms. We may also identify 
potentially interested volunteers from a Tulane volunteer recruitment registry. We will also 
consider recruiting potentially eligible individuals who were screened or participated in other 
clinical studies in our clinic and have expressed interest in being contacted about future 
research projects. Potential participants referred by their physician or community partners will 
have a pre-screening telephone interview to confirm potential eligibility. Those who are still 
interested and potentially eligible for the study will be scheduled for a screening visit. 
7.B. Randomization 
Once eligibility has been confirmed, the study coordinator will ensure that all key variables 
have been entered into the trial-specific database. Additionally, the study coordinator will ensure 
any outliers have been recognized and reconciled, and will ensure receipt of informed consent 
prior to enrolling the volunteer in the study as a trial participant. Eligible participants will be 
randomly assigned to the behavioral intervention or the usual diet group in a 1:1 allocation ratio. 
Randomization will be stratified by sex, using a random block group size (4, 6) to maintain 
balance among groups over time. A statistician from the Methodology/Biostatistics Unit within 
the COBRE Clinical Research Core, who is not directly involved in the study and is not located 
at the clinic, will conduct the randomization. After ascertaining eligibility, clinical personnel will 
telephone the Methodology/Biostatistics Unit to obtain a randomization assignment. All 
randomization assignments will be created by a computer program and only accessible to the 
Staff at the Methodology/Biostatistics Unit. Once randomization assignment has been made, 
trial participants will be considered to be officially randomized into the study and every effort will 
be made to obtain complete follow-up information.   
7.C. Masking 
Clinical and laboratory staff members who assess outcomes will be blinded to the 
intervention assignment of participants. As this is a dietary intervention trial, study participants, 
and study staff members who conduct the intervention cannot be blinded to the intervention 
assignment. Participants will be instructed to avoid sharing knowledge of their treatment 
assignment with data collection staff members. We will have intervention visits and data 
collection study visits on different days and in separate locations. Data collectors will also use 
verbal cues and visual props to remind participants not to disclose treatment assignment. 
Investigators will be blinded to intervention assignment. 

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7.D. Safety Considerations 
Participants with HbA1c >7.9% will be referred to a clinician for follow-up102, though we will 
continue to collect data on these participants.  
 
8. Dietary Intervention Program 
8.A. Low-carbohydrate dietary intervention group 
Participants randomized to the low-carbohydrate intervention group will receive counseling  
aimed at reducing carbohydrate consumption. Phase I (Go Low) will occur for the first 3 
months, with a goal of <40 g digestible carbohydrates per day. Key recommended foods will 
include: non-starchy vegetables, fish, poultry, lean meat, eggs, olive oil and other plant-based 
unsaturated oils, unsweetened/unsalted nuts and seeds, nut butters, and avocados. We will 
recommend moderate consumption of cheese and unsweetened Greek yogurt and low-
carbohydrate milk. During Phase I, we will recommend limiting or avoiding other dairy, fruits, 
legumes, beans, and grains. Phase II (Keep it Low) will run from months 4 through 6. The net 
carbohydrate goal for this phase will be <40 g to <60 g, with the objective to choose a target that 
is as low as possible (e.g., as close to <40 g as possible). At 3 months, we expect different 
participants will have different levels of intake, with some consuming <40 g of net carbohydrates 
and others consuming levels higher than 60 g net carbohydrates per day. We have designed 
the intervention to accommodate various scenarios, with the goal of achieving as low of an 
intake as possible. For participants who consume >60 g per day, we will recommend they aim to 
either reduce or maintain carbohydrate intake. 
At a brief check-in at 3-months, if participants are satisfied with their current intake, we will 
instruct them to stay at this intake level (though will recommend they try to reduce intake, if 
possible, if they are eating >60 net grams of carbohydrates or have not yet reached the study 
goal of <40 net grams of carbohydrates). If they prefer to make modifications, we will provide 
guidance on how to modify carbohydrate intake (either decrease or increase). If they choose to 
add back carbohydrates, we will recommend that participants add 5 grams of carbohydrates for 
two weeks at a time (e.g., from 40 to 45 g for 2 weeks), for a maximum total of <60 g net 
carbohydrates. If they choose to further reduce carbohydrate intake, we will provide guidance 
on this as well. As they modify carbohydrate intake, we will have them monitor their satisfaction 
with their diet and energy levels. If adding back carbohydrates, we will recommend participants 
add back in foods like fruit (preferably berries), legumes, beans, and dairy, while still aiming to 
keep total carbohydrate intake as low as possible (e.g., as close to <40 net grams as able).  
Materials: We will develop a handbook that will be given to participants. This will contain diet 
guidelines, recipes, meal planners, shopping lists, and guides for counting carbohydrates and 
reading nutrition labels.  
Meals: Participants will select their own menus and prepare or buy their meals according to the 
guidelines. We will provide participants with supplemental low-carbohydrate foods, such as 
nuts, olive oil, and other products, to help facilitate their compliance. 
Counseling: Sessions and materials will focus on instructing participants to reduce digestible 
carbohydrate consumption by increasing consumption of protein and fat, with a particular 
emphasis on increased consumption of heart-healthy unsaturated fats. After randomization, 
participants will begin the 3-month Go Low phase consisting of individual counseling sessions 
each week for the first four weeks, followed by 4 group sessions held every other week with 
phone follow-ups occurring in between group sessions. During the Keep it Low phase, months 4 
through 6, participants will attend 3 monthly group sessions and have 3 telephone follow-ups. 
There will be a total of 11 in-person sessions and 7 telephone follow-ups over the full study 

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period. Sessions will be approximately one hour and phone calls will be no longer than thirty 
minutes. These sessions will consist of diet instruction and supportive counseling, addressing 
results from 24-hour dietary recalls, teaching self-monitoring and individual diet goal changes, 
and provide suggestions for replacing usual foods containing carbohydrates. Study materials 
will be modified from materials used in the successful MACRO study. The JFI will work closely 
with Drs. He and Bazzano to develop the intervention based on the MACRO study. 
Carbohydrate goal: In the MACRO study, carried out among individuals from the same study 
region, a behavioral intervention aimed at reducing digestible carbohydrate intake to <40 g/day 
led to reductions in weight and improvements in cardiovascular risk factors among individuals 
with obesity.30 Additionally, restriction of carbohydrate intake to <50g/day is sufficient to induce 
ketosis.103 Our rationale for having a multi-phased intervention is to allow participants to see 
how they feel on the more restrictive diet, and see how they respond to small increases in 
carbohydrate consumption. A similar technique was applied in the DIETFITS published study.104 
The higher target of 60 net grams may be more sustainable long-term and also allows for 
consumption of healthy higher-carbohydrate foods, such as berries, legumes, beans, and 
limited whole grains.   
8.B. Usual Diet Group   
We will provide participants randomized to the usual diet group written information with 
standard dietary advice. Participants randomized to the usual diet group will not receive ongoing 
dietary recommendations. Moreover, they will continue to receive clinical care recommendations 
from their physician(s). To encourage continued participation in the study and minimize the 
difference in participant contact with study staff, participants will be offered optional monthly 
educational sessions on topics unrelated to the study intervention, such as retirement planning 
or health insurance options. 
In another effort to encourage continued participation, patients randomized to the usual diet 
group will be offered a copy of all available intervention materials, as well as an optional one-
hour counseling session with the interventionist following their final study visit.  
8.C. Physical Activity 
At baseline, both groups will receive written information in study materials with standard 
physical activity recommendations.  
8.D. Dietary Adherence 
Strategies for measuring compliance: For the low-carbohydrate diet, adherence will be 
assessed through measurement of urinary ketones at 3-month visit and 6-month TV. Study staff 
will make all reasonable effort to maintain adherence of participants to the visit schedule and 
diet intervention.  
Strategies for improving compliance:   
• 
At the screening visit, we will ask participants who does most of the cooking in their 
households and how often they eat outside of the home. Results from the screening visit 
will help to select a group of cooperative study participants.  
• 
Visits will be scheduled at the participants’ convenience and to minimize waiting time 
and trips to the clinic; reminder calls, texts or emails (chosen based on participant 
preference) will also be made prior to clinic visits.  
• 
We will hire enthusiastic staff who have good interpersonal skills. 
• 
Participants will receive $40 gift cards for use at food stores or retailers when they 
complete each study visit, for a maximum of $120 over the study period. 
• 
Participants will receive $25 gift cards when they return the stool specimens, for a 
maximum of $75 over the study period. 

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• 
Participants will receive a $25 gift card when they return the continuous glucose monitor, 
for a maximum of $25 over the study period. 
• 
Participants will be offered small gifts (such as pens or magnets with study logo) to 
encourage compliance and adherence to the study protocol. 
• 
Participants will be provided with recipes, shopping lists, and food samples for the 
intervention diet. 
 
9. Safety of Dietary Intervention 
On the low-carbohydrate diet, participants will be encouraged to primarily focus on replacing 
carbohydrates (particularly highly refined carbohydrates) with foods such as non-starchy 
vegetables, olive oil and other plant-based unsaturated oils, nuts and seeds, avocados, eggs, 
seafood, tofu, poultry, and lean meat. Consumption of more unsaturated fats, protein, and fiber 
will be recommended. Participants will not be encouraged to increase consumption of saturated 
fats and will be advised to avoid consumption of trans fats.  
In animal studies, a high-protein diet has decreased renal function105 In the MACRO study, 
on average, participants tended to increase consumption of fats, rather than protein.30 The 
safety and tolerability of low-carbohydrate diets have previously been assessed in many 
studies, including MACRO.30 A number of studies, including some in individuals with T2D, have 
found no clinically significant increases in estimated glomerular filtration rates,33,38–40 
microalbuminuria,106 albumin excretion rate,33,38 urinary albumin,38 serum creatinine,38,40,106–111 
albumin,40 or uric acid levels.107–110 A small study of a very low-carbohydrate diet found 
significant increase in uric acid excretion, but no significant change in 24-hour urine creatinine 
clearance.110  
Study staff will carefully monitor participants’ BP, and HbA1c more often than what would 
occur in routine healthcare visits. A Data Safety and Monitoring Board (DSMB) consisting of an 
independent group of experts in areas such as biostatistics, nutrition medicine, general internal 
medicine, and endocrinology has been formed. The board will regularly review trial progress, 
including unblinded interim results, and can recommend that the trial prematurely end if 
participants are at risk or if it becomes clear that the trial will not be able to yield statistically 
significant results. 
 
10. Data Collection 
10.A. Study visits 
After the initial pre-screening interview, in which data on medications and medical conditions 
will be collected, there will be one screening visit, one randomization visit, a follow-up study visit 
at 3 months and a termination visit (TV) at 6 months. Table 3 summarizes study procedures and 
data collected at each study visit. 
 
 
 

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Table 3. Study visit schedule and data collection 
 
Pre-
screen 
SV 
RZ 
3 month 
6 month TV 
Pre-screen eligibility 
X 
 
 
 
 
Informed consent 
 
X 
 
 
 
Compliance form 
 
X 
 
 
 
Eligibility confirmation 
 
 
X 
 
 
Randomization 
 
 
X 
 
 
Demographics 
 
X 
 
 
 
Medical history 
questionnaire 
 
 
X 
X 
X 
Medications 
 
X 
X 
X 
X 
Lifestyle (alcohol, 
cigarette smoking) 
 
 
X 
X 
X 
Physical activity 
 
 
X 
X 
X 
24-hour diet recall* 
 
 
X 
X 
X 
3 BP measurements 
 
X 
X 
X 
X 
Body weight 
 
 
X 
X 
X 
Height 
 
 
X 
 
 
Waist circumference 
 
 
X 
X 
X 
Spot urine test 
 
 
X 
X 
X 
Blood samples 
 
X 
X 
X 
X 
Stool specimen 
 
 
X 
X 
X 
Side-effects 
assessment 
 
 
 
X 
X 
X 
Nut Consumption 
 
 
 
 
X 
CGM** 
 
 
 
 
X 
*Two 24-hour dietary recalls will be collected; one should cover a weekend and the other a 
weekday. 
**The CGM will be worn for up to 14 days prior to the 6-month TV and returned at the TV or by 
mail. Participants will come in for a 6-month CGM visit (prior to the 6-month TV) to have the 
CGM inserted.  
 
10.A.1. Screening/baseline visits:  
Participants will be pre-screened by phone or in-person by study staff to confirm eligibility for 
the Screening Visit. An approved questionnaire will be used to ensure the patient is eligible to 
attend the in-clinic screening visit, and the patient will be scheduled thereafter. 
At the screening visit (SV), participants will provide informed consent for the screening and 
main study. Study staff will schedule the SV and randomization (RZ) visit at least 2 days apart. If 
a participant is eligible based on the screening visit, he or she should be scheduled for the RZ 
once a sufficient group of eligible individuals has been recruited. Participants should be 
scheduled for the RZ at least 2 days and no more than two weeks after the screening visit.  
At the screening visit, we will collect information on inclusion/exclusion criteria, medication 
use, and demographics. At this visit, we will also have participants complete a compliance form, 

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to assess their ability to complete the study and attend all intervention and study visits. We will 
also measure blood pressure, and take blood samples. Women will be asked if they are 
postmenopausal or if they had surgical sterilization (such as a tubal ligation). If not, they will be 
tested for pregnancy through a spot urine test; pregnant women will be excluded from the study. 
Blood samples will be collected for measurement of HbA1c, and, if not available from medical 
records in the past 3 months, serum creatinine and hemoglobin. These blood samples will be 
used for excluding individuals with HbA1c <6.0 or >6.9, eGFR ≤45 mL/min/1.73 m², or 
hemoglobin <11 mg/dL.  
Before the start of the intervention, participants will complete two 24-hour dietary recalls. At 
least one (and potentially both) 24-h recalls will be collected by phone. At the RZ, participants 
will learn about the randomization process. After requirements for eligibility have been satisfied, 
participants will formally be enrolled into the study and randomized to either the active 
intervention or control group.  We will collect fasting blood samples for later measurement of 
glucose, insulin and lipids and other potential future measurements. At this visit, we will 
measure blood pressure, body weight, height, and waist circumference. We will collect 
information on medical history, lifestyle risk factors, and physical activity. A spot urine sample 
will be collected to measure ketones and other markers and participants will be asked to collect 
a stool specimen for potential use in future microbiome studies.  
 
10.A.2. Follow-up visits and final visit: A follow-up visit will occur at 3 months after 
randomization. A final visit will occur at 6-months post-randomization. These visits should be 
scheduled as close as possible to the 3-, or 6-months after randomization. At each visit, study 
staff will conduct dietary recalls and anthropometric measures, take 3 BP measurements, collect 
a fasting blood sample to measure HbA1c. At least one (and potentially both) 24-h recalls will be 
collected by phone. We will also collect samples for later measurement of glucose, insulin, lipid 
profile, and other potential future measurements. A spot urine sample will be collected to 
measure ketones and other markers. Participants will be asked to collect a stool specimen for 
potential use in future microbiome studies.  Information about participants’ nut consumption over 
the past 6 months will be collected at the 6-month TV. At study termination, we will mail 
participants and/or their physicians a summary of trial results and a record of participant BP, 
anthropometric measures, and laboratory data from the trial period. Throughout the study 
period, we will provide participants with their blood pressure and weight. We will request that, if 
possible, a participant who is prescribed a diabetes medication during the course of the study 
comes into the clinic for an additional separate supplemental visit for a fasting blood sample 
collection prior to starting the medication. Maintaining follow-up of all randomized participants is 
of utmost importance to ensure data integrity. In the event that a participant moves during the 
study we may request that the participant provides a fasting blood sample at a local LabCorp 
facility (this will be described on the informed consent form). 
 
10.A.3. CGM 6-month visit: Individuals who are willing to wear the CGM prior to their 6-month 
termination visit will come to the research clinic approximately 2 weeks before their 6-month 
termination visit for their CGM visit. At this time, they will have a factory-calibrated CGM inserted 
just under the skin of the upper arm and activated.112 If the CGM falls off of a participant prior to 
14 days of wear, we may request that the participant (if willing) returns to the clinic for the CGM 
to be re-inserted. The CGM will be returned at the 6-month TV, or by mail.  

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10.B Study measurements 
Measurements obtained for this study will be based on those used in other clinical trials and 
epidemiologic studies. We are familiar with strengths and limitations of such measurements and 
the importance of staff training and certification and use of stringent quality control procedures. 
10.B.1. Questionnaires: Study staff will administer a medical history questionnaire at the RZ, 
3-month visit and 6-month TV to assess medical conditions that would necessitate changes in 
therapy or medical management beyond this study’s scope. At the SV, demographic factors will 
be collected. At the SV, RZ, 3-month and 6-month TV, we will also administer medication 
tracking questionnaires. At RZ, 3-month, and 6-month TV, we will collect health behavior and 
physical activity data. 
10.B.2. Dietary measurements: Two 24-hour dietary recalls will be obtained from participants 
at baseline. At or close to both the 3-month and 6-month TV, two more 24-hour dietary recalls 
will be collected. The second sets of two recalls will be collected as closely as possible to 3- or 
6-month dates after randomization, with a goal of being within 2 weeks of the respective follow-
up period.  For each time point, one recall should reflect week day consumption, while the other 
should reflect weekend day consumption and the two recalls should be at least 2 days apart 
from each other. We will use computer software (Nutrition Data System for Research [NDS-R]) 
and food models used in previous and ongoing studies. Recalls will be conducted by a study 
staff member who has been certified in the use of NDS-R. Food composition tables of the NDS-
R will be used to calculate dietary nutrient intakes. The baseline dietary assessment will be 
done to characterize individual dietary intake of carbohydrates and other macronutrients. During 
the intervention, repeated measurements will be used to monitor short-term changes in mean 
dietary nutrient intake between the intervention and usual diet groups.  
10.B.3. Assessment and management of adverse effects: At RZ, 3-month visit, and 6-month 
TV, we will administer symptom questionnaires, which will consist of a checklist to identify 
participant complaints. Prior studies of low-carbohydrate dietary interventions suggest that 
participants may experience a range of adverse effects, including constipation, halitosis, fatigue, 
headache, thirst, polyuria, and nausea. Severe adverse events will be promptly reported to the 
DSMB. Management of adverse effects will be based on the protection and safety of the 
participant. If severe adverse effects are reported by a participant, carbohydrate intake will be 
examined and altered in order to mitigate the adverse effect. In any extreme cases, participants 
will be instructed to stop the intervention. As this is a behavioral intervention, adverse effects 
should be rare. 
10.B.4. BP and anthropometric measures: BP will be measured 3 times at the screening visit 
and at each follow-up visit. To minimize random error, averages of the measurements at the 
screening and randomization visits will be taken. BP will be measured by a standard automated 
blood pressure measurement device (OMRON HEM-907 XL Professional Digital Blood 
Pressure Monitor) and performed by experienced staff, trained and certified in BP 
measurement. Prior to BP measurements, participants will be asked to rest quietly in a seated 
position with their feet supported for at least 5 minutes; staff members will use an appropriate 
cuff size over a bare arm. Trained and certified staff will measure weight using a calibrated 
balance beam scale at the screening visits, and follow-up visits. Weight and height will be 
measured at the RZ, and weight will also be measured at the subsequent visits. 
10.B.5. Blood samples: For SV, participants will not need to fast. For RZ, 3-month visit, and 6-
month TV, participants will be instructed to fast for 12 hours prior to blood sample collection.  At 
SV, blood samples will be collected to measure HbA1c, hemoglobin, and serum creatinine.  At 
RZ, fasting blood samples will be collected and stored as serum/plasma, whole blood aliquots 
and buffy coats at -80°C for future analyses, including measurement of glucose, insulin and 
lipids, and potential future metabolomics or genetic analyses. At 3-month visit and 6-month TV,  

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we will collect fasting blood samples to measure HbA1c and will also store additional 
serum/plasma, whole blood aliquots and buffy coats at -80°C for future analyses, including 
measurement of glucose, insulin and lipids, and potential future metabolomics or genetic 
analyses. Details of the blood sample collection are shown in Table 4. In the event that a 
participant moves, we may request that they collect a fasting blood sample at a local LabCorp 
and we will measure HbA1c, glucose, insulin, and lipids at the 3 and 6-month visits. HOMA-IR 
will be calculated from fasting glucose and insulin. 
HbA1c will be measured at LabCorp (Roche Tina Quant; fresh samples) from whole blood 
collected at screening, 3-month, and 6-month visits. Following trial completion, to improve 
precision of HbA1c estimates, HbA1c will also be measured at the Diabetes Diagnostic 
Laboratory (ion-exchange method; Tosoh G8 HPLC Analyzer; frozen samples) from whole 
blood collected at randomization, 3-month, and 6-month visits. Samples with Hb variants (C, D, 
E, S) that are measured at the Diabetes Diagnostic Laboratory will be reflexed for measurement 
by boronate affinity HPLC (Trinity Premier Hb9210).113 
 
Table 4. Study visit schedule for specimen collection 
 
SV 
RZ 
3 month 
6 month TV 
HbA1c 
X 
 
X 
X 
Serum creatinine 
X 
 
 
 
Hemoglobin 
X 
 
 
 
Storage of aliquots and 
buffy coats (for 
measurement of 
glucose, insulin, lipids, 
other potential future 
measurements) 
 
X 
X 
X 
Urine sample for 
pregnancy 
X 
 
 
 
Urine sample for 
ketones and other 
markers 
 
X 
X 
X 
Stool sample 
 
X 
X 
X 
CGM 
 
 
 
X 
 
10.B.6. Urine collection: Study staff will collect spot urine specimens at RZ, interim visit, and 
the final visit to measure ketones. 
10.B.7. Stool Specimen Collection: Stool samples will be collected from all eligible and willing 
trial participants during the RZ, 3-month, and 6-month TV, following the protocol set forth by the 
Human Microbiome Project.114,115 Participants will be given a stool collection kit, which includes 
the specimen collection container, a shipper for home collection, and a form to record the timing 
and pertinent information related to specimen collection. Participants will be instructed to return 
the kit to the clinic within two days of collection (in-person or via shipping), at which time stool 
samples are stored at -80°C until analyses. Kits and instructions for collection will be reviewed by 
study staff with the participant at the required visits.  
 

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10.B.8. CGM at 6 months: Approximately two weeks before their 6-month termination visit, 
participants willing to wear the CGM will come to the clinic to have their CGM inserted. This CGM 
has been found to be accurate compared with capillary blood glucose reference values over 14 
days of wear.112 This CGM records interstitial glucose every 15 minutes throughout the day for a 
period of up to 14 days. The sensor uses a thin, flexible filament inserted just under the skin to 
measure glucose and is read through near-field communication by touching the reader to the 
sensor. For quality control of the CGM data, a subset of participants who wear the CGM will be 
asked to wear two CGMs at the same time, one on each arm. Prior to insertion, one arm will be 
designated as the arm used for data collection and the other arm as a duplicate. 
11. Quality Assurance and Quality Control 
Throughout the study, we will implement rigorous quality assurance (QA) and quality control 
(QC) measures. We describe some of these approaches here.  
11.A. Manual of procedures 
We will develop a manual of procedures (MOP) based on the MOP successfully used in the 
MACRO behavior change clinical trial. The MOP will provide instructions and describe 
procedures for staff training and certification, participant recruitment, intervention counseling, 
study form completion and procedures, data entry, safety measures (e.g., methods for 
emergency participant/primary care physician contact). 
11.B. Training and certification 
Trial personnel will all be required to participate in a training session before the start of any 
trial procedures or measurements. Training will include particular attention to core trial 
elements, such as recruitment, retention, intervention, completeness and quality of data 
acquisition (e.g., blinding procedures for the data collectors), and data entry. Separately, 
intervention staff will meet and receive detailed instruction on trial approaches to group and 
individual behavior change counseling and procedures that ensure data collectors are blinded to 
treatment assignment. Throughout the trial, periodic re-training/certification sessions will be 
conducted to ensure all trial-related procedures are being applied in a standard manner. 
Investigators will also monitor all aspects of study performance to ensure study goal 
achievement, timeliness and completeness of study visits, completeness and quality of data 
collection, intervention adherence, and adequacy of the procedures separating data collection 
from intervention. Study staff and investigators will pay particularly careful attention to the 
quality of all laboratory measurements, particularly key exposure, outcome, and intervention 
monitoring variables.  
 
12. Sample Size and Statistical Power 
The primary outcome will be the difference in the change of HbA1c between the intervention 
and usual diet groups from baseline to 6 months of follow-up. Preliminary data from ADEPT 
suggests that the SD of the 6-month change in HbA1c is 0.28%, with preliminary 6-month 
follow-up >90%. Based on an estimated standard deviation of change in HbA1c of 0.35% and 
95% follow-up, we would need 142 participants to have 80% power to detect a difference in the 
change in HbA1c from baseline to 6 months of 0.17% between the intervention and usual diet 
groups. Assuming 95% follow-up, we would need 150 total participants.   
In a follow-up analysis of the DPP, a 0.15% decrement in HbA1c at 6 months was 
associated with a 16% lower risk of incident T2D, adjusting for treatment arm, age, sex, 
race/ethnicity, household income, and baseline HbA1c.116 In a pooled analysis from the 
Atherosclerosis Risk in Communities and Framingham Heart Studies, a 0.15% higher HbA1c 
was associated with an 16% higher risk of T2D over 20 years, a 30% higher risk over 8 years, 
and a 13% higher risk after 8 years, after adjusting for age, sex, fasting glucose, triglycerides, 

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HDL, family history of T2D, SBP, and BMI.117  Additionally, in EPIC-Norfork, a difference of 
HbA1c of 0.15% was associated with approximately a 5% higher risk of CHD among those free 
of CHD, stroke, diabetes, and with HbA1c <7.0%.118 
In the DPP study, HbA1c was 0.15% lower among those in the lifestyle intervention arm 
than in the control arm at 6-months follow-up; HbA1c at study commencement was 5.9% and 
levels increased in the control arm and decreased in the behavioral intervention arm.22  In a 
small behavioral intervention study (n=34) of a very low-carbohydrate ketogenic diet compared 
with a moderate carbohydrate, calorie-restricted, low-fat diet among individuals with type 2 
diabetes or prediabetes (HbA1c >6.0%) and elevated body weight (BMI >25), mean HbA1c  
decreased from 6.6% to 6.1% in the 
very low-carbohydrate group and from 
6.9% to 6.7% in the moderate 
carbohydrate group over a 12-month 
period; additionally, the very low-
carbohydrate group had greater 
reductions in glucose-lowering 
medications.37 
Detectable differences are listed for 
HbA1c and secondary outcomes in 
Table 5, based on data from prior 
studies.30,53,56,119 These were calculated 
for unpaired t-tests, power of 80%, two-
sided alpha of 0.05, and assuming 95% 
follow-up of 150 participants, which 
would yield an estimated 142 
participants. 
 
13. Data Management and Analysis 
13.A. Data management 
Personnel will double-enter all study data. Prior to entering data, the study coordinator will 
conduct quality control on all study forms, study measures, and laboratory data. Data will be 
cleaned and logically checked. 
13.B. Data analysis plan 
The data will be analyzed using intention to treat; this involves comparing the primary and 
secondary outcomes between participants based on randomization assignment.  
13.B.1. Exploratory data analysis: We will express group data for variables with a normal 
distribution as mean ± standard deviation and for variables not normally distributed as median 
and interquartile ranges (or will log-transform the variables to obtain a normal distribution). We 
will compare means and percentages of baseline variables across the intervention and usual 
diet group to assess similarity of these groups at randomization. 
13.B.2. Primary, secondary, and exploratory outcomes: We will test the primary study 
hypothesis that there is a greater reduction in HbA1c from baseline to 6 months in the 
intervention group than in the usual diet group. To do this, we will use linear regression with 
change in HbA1c from baseline to 6 months as the dependent variable 
 
Table 5. Minimum detectable differences 
Change from baseline to 
6 months in 
SD 
Detectable 
Difference 
HbA1c, % 
0.35 
0.17 
Fasting glucose, mg/dL 
12.5 
5.9 
Fasting insulin, mU/mL 
7.0 
3.3 
HOMA-IR 
2.0 
0.95 
SBP (mmHg) 
4.2 
2.0 
DBP (mmHg) 
3.0 
1.4 
Total/HDL ratio 
1.2 
0.57 
Body weight (kg) 
6.6 
3.1 
Waist circumference (cm) 
8.0 
3.8 
Estimated CVD risk (%)* 
6.7 
3.4 
*10-y CVD risk, among estimated 85% or 126 
participants free of CVD 

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We will use Bland-Altman plots to explore whether there is a systematic difference in HbA1c 
measured by LabCorp compared with DDL. If there is not a systematic difference in HbA1c 
measured at these two laboratories, to improve precision in the estimate of the primary outcome 
(difference in change in HbA1c between the intervention and control groups), we will use the 
weighted average of change in HbA1c measures from the two labs as the outcome (weights 
defined as the ratio of the variance for each lab over the sum of the variance) (50). If we 
observe a systematic difference between HbA1c measured at LabCorp and DDL, we will use 
HbA1c measured at DDL. 
We will use a similar approach to test the difference in the change between baseline and 6-
month values of secondary outcomes (Specific Aim 2) and exploratory outcomes. In exploratory 
analyses, we will also test the difference in the change between baseline and 3-month values of 
outcomes (HbA1c, fasting glucose, systolic blood pressure, total-to-HDL cholesterol, body 
weight, insulin, HOMA-IR, diastolic blood pressure, waist circumference, and estimated CVD 
risk). We will also explore the use of mixed effects models to assess overall net change in 
HbA1c (by treating time as a linear variable) and other outcomes over the full study period. For 
each outcome, we will test modeling assumptions and will consider transformation of outcomes, 
if needed, to meet modeling assumptions. We will also perform sensitivity analyses using 
Markov-chain Monte Carlo techniques to impute missing values of the outcomes, using 
covariates for this imputation and will compare results from this analysis with our primary 
findings.  
 
15. Anticipated Challenges 
Recruitment: Many clinical trials have challenges recruiting sufficient numbers of volunteers 
who meet the trial inclusion and exclusion criteria and demonstrate a high level of adherence to 
trial protocol requirements. Fortunately, the investigators are very experienced with clinical trial 
recruitment, and have several contingency options that can be used to meet unanticipated 
shortfall in recruitment. 
Intervention: The investigators are aware of and understand challenges related to achieving 
and maintaining compliance with a behavioral intervention. The investigators have much 
experience and success in behavioral interventions, with recent success of a behavioral 
intervention aimed at reducing carbohydrate intake among participants from the New Orleans 
area. The JFI will collaborate with Drs. He and Bazzano to develop the intervention program 
based on the MACRO study and will assess potential barriers to implementation and 
intervention adherence (such as financial concerns and range of dietary patterns of study 
participants) during the planning and pilot phase of the study. 
Adherence: Though adherence and follow-up are also main challenges related to clinical trials, 
the investigators have an outstanding track record for studies that have recruited participants for 
both clinical and epidemiology studies in the Greater New Orleans area. To encourage 
adherence, small gifts (such as pens or magnets with study logo) will be offered to all study 
participants. 
 
16. Protection of Human Subjects 
This Human Subjects Research meets the definition of a clinical trial. All investigators will be 
required to complete the CITI (Collaborative Institutional Training Initiative) program in the 
ethical use of human participants in research. 
16.A. Protection of human subjects from research risks 
 

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16.A.1. Risks to the subjects 
Human subject involvement and characteristics: We expect to enroll 150 participants, with 
an equal male to female ratio. We expect to enroll approximately 35 participants who are 
African-Americans, and another 12 with mixed racial backgrounds, and a few Asian participants 
given the demographics of the greater New Orleans area. Overall, given the demographics of 
greater New Orleans, we estimate approximately 10% participants of Hispanic or Latino 
ethnicity, 50% of them with African-American racial background. 
 
Inclusion criteria 
• 
Men or women ages 40 to 70 years: aim to recruit 50% women 
• 
Any race or ethnicity: aim to recruit 40% ethnic minorities (i.e., African American and 
Hispanic), close to population in the greater New Orleans area98 
• 
HbA1c 6.0–6.9% 
• 
Willing and able to provide informed consent 
Exclusion criteria 
• 
Diagnosed type 1 diabetes mellitus based on patient self-report 
• 
Use of agents affecting glycemic control (medications for diabetes, oral glucocorticoids) 
within the past three months prior to enrollment based on patient self-report 
• 
Medical condition in which low-carbohydrate diet may not be advised  
o Estimated glomerular filtration rate (eGFR) ≤45 mL/min/1.73 m², which is close to 
the 5th percentile of eGFR among non-diseased individuals of 70 years of age99  
o Self-report of liver disease due to hepatitis or alcohol; osteoporosis; untreated 
thyroid disease; gout; or cancer (other than non-melanoma skin cancer) requiring 
treatment in the past year, unless prognosis is excellent 
• 
Factors that may affect HbA1c:  
o Hemoglobin <11 mg/dL (cutpoint for moderate-to-severe anemia, which could 
lead to falsely elevated or lowered HbA1c)100   
o Recent blood donation or blood transfusion (self-report, past 4 months) 
o Human Immunodeficiency Virus (self-report)101 
• 
Self-reported history of intensive care unit stay due to Coronavirus Disease 2019 
(COVID-19) in the past three months, as severe COVID-19 may affect blood glucose 
levels 
• 
Allergies to nuts 
• 
For women, current pregnancy, breastfeeding, or plans to become pregnant during the 
study 
• 
Consumption of ≥21 alcoholic drinks per week or consumption of ≥6 drinks per occasion 
• 
For the CGM collection at the end of the study period only: known allergy to adhesives 
or other products involved with CGM use (e.g., skin disinfectants), current pregnancy, 
currently on hemodialysis or peritoneal dialysis, or people with other implanted medical 
devices (e.g., a pacemaker) 
• 
Current or planned residence making it difficult to meet trial requirements (due to 
distance from study site and/or challenges regularly traveling to site) 
• 
Current participation in another lifestyle intervention trial or a pharmaceutical trial 
• 
Participation of another household member in the study; employees or persons living 
with employees of the study 
• 
Other concerns regarding ability to meet trial requirements, at the discretion of the 
principal investigator or study coordinator 

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Sources of materials: Medical information data will be collected from the participant and, after 
written authorization for the disclosure of protected health information, from participants’ medical 
records. Blood and urine samples will be collected to measure HbA1c, glucose, insulin, lipids, 
creatinine, ketones, and test for pregnancy. Blood pressure, height, weight, waist circumference 
and other physical measurements will be obtained. 
 
Potential Risks: Risks associated with venipuncture, the diet intervention, CGM insertion, and 
collection of confidential medical information are the main risks associated with this study. There 
is a small risk of bruising and a rare chance of local infection associated with standard 
venipuncture to collect blood samples. The risks of wearing the CGM are minimal. There is a 
very low risk for local infection at the skin site where the sensor is inserted into the skin. 
Possible symptoms associated with the CGM sensor application or the adhesive used to keep 
the sensor in place include skin irritation or redness, skin inflammation, pain or discomfort, 
bleeding, bruising, swelling, skin rash, itching, scarring or skin discoloration, or allergic reactions 
to the sensor needle or adhesives. Sensors may fracture in situ on rare occasions. The dietary 
intervention has minimal risks. Reduced carbohydrate consumption may lead to adverse effects, 
including constipation, halitosis, fatigue, headache, thirst, polyuria, and nausea. At RZ, 3- , and 
6-month visits, we will administer symptom questionnaires, which will consist of a checklist to 
identify participant complaints. Adverse effects of the low-carbohydrate diet will be assessed at 
counseling sessions. Severe adverse events will be promptly reported to the DSMB. 
Management of adverse effects will be based on the protection and safety of the participant. If 
severe adverse effects are reported by a participant, carbohydrate intake will be examined and 
altered in order to mitigate the adverse effect. In any extreme cases, participants will be 
instructed to stop the intervention. Furthermore, there is a potential risk of unauthorized 
disclosure of medical information. This risk will be minimized by using a strict protocol for data 
processing and by the appropriate training of all study personnel. Protection against risks is 
described in more detail below. 
 
16.A.2. Adequacy of protection against risks 
Recruitment and Informed Consent: The proposed study will be conducted following strict 
guidelines for the protection of the rights of human volunteers. The informed consent document 
will be signed by all participants at the screening/baseline visit. The informed consent form will 
be developed in the first year of the study and approved by the IRB. The consent form will 
clearly state the purpose, eligibility criteria, and protocol of the study, the potential benefits and 
risks of participation, and the subject's right to refuse to participate or withdraw. Prior to signing 
the informed consent, research staff will review the details of the consent form orally with the 
participant, and answer any questions that the participant has concerning participation in the 
study. In the case of potential participants with low or no literacy, the informed consent form will 
be read to the participant in its entirety and any questions will be answered prior to the 
participant signing or marking the form. Specifically, the following must be accomplished during 
the informed consent process:  
• 
The participant must be informed that participation in the study is voluntary and that 
refusal to participate will involve no penalty or loss of benefits. 
• 
The participant must be informed of the purpose of the study and that it involves 
research. 
• 
The participant must be informed of any alternative procedures, if applicable. 

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• 
The participant must be informed of any reasonably foreseeable risks. 
• 
The participant must be informed of any benefits from the research. 
• 
An outline of safeguards to protect participant confidentiality will be included, as well as 
an indication of the participant’s right to withdraw without penalty. This should be 
balanced with a discussion of the effect that withdrawals will have on the study, and the 
responsibility a participant has, within limits, to continue in the study if he or she decides 
to enroll. 
• 
The participant must be informed of his or her right to have questions answered at any 
time and whom to contact for answers or in the event of research-related injury. 
• 
The participant must be informed as to whether or not compensation is offered for 
participation in the study and/or in the event of a medical injury. 
• 
The participant must be informed that he/she will be notified of any significant changes 
in the protocol that might affect their willingness to continue in the study. 
Written authorization for the disclosure of protected health information will be obtained during 
the consent process on a separate form (HIPPA authorization), if applicable.  
Protection against Risk: The protocol and informed consent will be approved by the 
Institutional Review Boards at Tulane University Health Sciences Center and any other 
participating institution for recruitment. The study participants will be given contact information 
for the Study Coordinator and Study PI to answer questions or to report complaints. Patients 
can withdraw from the study at any time without any effect on their medical care. Standard 
techniques will be used by trained, certified phlebotomists or study nurses for blood sample 
collection at the study clinics where emergency medical equipment is available. Confidentiality 
of all data collected during the study will be maintained through the use of unique, encrypted 
study identification (ID numbers, rather than patient names, in the study database). These 
encrypted ID numbers will not be mathematical derivation of the subject’s medical record 
number or any other patient identifier. No information will be disclosed in an individually 
identifiable form in any type of presentation or publication. There will be password-required 
access to the computerized file linking the study numbers to patient identifiers at the study 
clinics. Password-access will be restricted to pertinent research staff only. All study data will be 
kept in locked file cabinets in locked rooms, accessible only by study staff with permission. All 
data transmissions will use HIPPA-compliant password protected system and will be secured 
through a virtual private network. 
 
16.A.3. Potential benefits of the proposed research to human subjects and others 
Study participants may have improved glycemic outcomes, blood pressure, lipid levels, may 
lose weight and reduce waist circumference, and may have improvement in other risk factors for 
CVD and development and progression of T2D. Participants will receive multiple blood 
pressure, weight, waist circumference, and blood tests. If vital signs or lab values are clinically 
abnormal, participants will be referred to their primary care physician, or if they do not have a 
primary care physician, one will be assigned through the Tulane University Community Health 
Center, which is a part of the core clinical facilities. At the end of the study, we will provide the 
participants’ primary care physician with a copy of all the blood pressure, weight, laboratory 
results, and (if applicable) CGM results.  
 
16.A.4. Importance of knowledge to be gained 
Information from this study may contribute to reducing the onset of T2D and the burden of 
T2D and cardiovascular disease in Louisiana and the general US population. The study has 

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potential for public health impact; results from this study may provide evidence in support of 
promoting alternative dietary styles (than the most commonly used low-fat diet) among 
individuals with high T2D risk or with T2D. 
 
16.A.5. Remuneration 
For screening visit 2, the two follow-up visits, and the final visits, participants will receive $40 
gift cards for use at food stores or retailers (after completing each study visit), for a maximum of 
$120 over the study period. Participants who return a stool sample will receive $25 gift cards for 
each stool sample that they return, for a total of $75 for three stool samples. For the CGM 6-
month study, participants will receive $25 gift cards for returning the CGM, for a maximum of 
$25. Participants will also receive free parking for each intervention and study visit. 
16.B. Data safety and monitoring plan 
A DSMB, which consists of 3 experts who are not otherwise affiliated with the COBRE 
program, has been formed. Study investigators for this study will prepare accurate and timely 
data tables and reports for the DSMB meetings. The members of the DSMB will serve in an 
individual capacity and provide their expertise and recommendations. The primary 
responsibilities of the DSMB are: 1) periodically review and evaluate the accumulated study 
data for participant safety, study conduct and progress, and, when appropriate, efficacy, and 2) 
make recommendations to the NIH concerning the continuation, modification, or termination of 
the trial. The DSMB considers study-specific data, as well as relevant background knowledge, 
about the disease, test agent, and patient population under study. 
The DSMB is responsible for defining its deliberative processes, including event triggers that 
would call for an unscheduled review, stopping guidelines, unmasking (unblinding) and voting 
procedures prior to initiating any data review. The DSMB is also responsible for maintaining the 
confidentiality of its internal discussions and activities, as well as the contents of reports 
provided to it. 
The DSMB will review each protocol for any major concerns prior to implementation. During 
the trial, the DSMB should review cumulative study data to evaluate safety, study conduct, and 
scientific validity and integrity of the trial. As part of this responsibility, DSMB members must be 
satisfied that the timeliness, completeness, and accuracy of the data submitted to them for 
review are sufficient for evaluation of the safety and welfare of study participants. The DSMB 
should also assess the performance of overall study operations and any other relevant issues, 
as necessary. 
 
Items reviewed by the DSMB include: 
• 
Interim/cumulative data for evidence of study-related adverse events; 
• 
Interim/cumulative data for evidence of efficacy according to pre-established statistical 
guidelines, if appropriate; 
• 
Data quality, completeness, and timeliness; 
• 
Adequacy of compliance with goals for recruitment and retention, including those related 
to the participation of women and minorities; 
• 
Adherence to the protocol; 
• 
Factors that might affect the study outcome or compromise the confidentiality of the trial 
data (such as protocol violations, unmasking, etc.); and, 
• 
Factors external to the study, such as scientific or therapeutic developments, that may 
impact participant safety or the ethics of the study. 
 

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The DSMB will conclude each review with their recommendations to the COBRE program 
and NIH/NIGMS as to whether the study should continue without change or be modified or 
terminated. Recommendations regarding modification of the design and conduct of the study 
could include: 
• 
Modifications of the study protocol based upon review of the safety data; 
• 
Suspension or early termination of the study or of one or more study arms because of 
serious concerns about subjects’ safety, inadequate performance or rate of enrollment; 
• 
Suspension or early termination of the study or of one or more study arms because 
study objectives have not been obtained according to pre-established statistical 
guidelines; and, 
• 
Corrective actions regarding a study when the performance appears unsatisfactory or 
suspicious. 
 
Confidentiality must always be maintained during all phases of DSMB review and 
deliberation. Usually, only voting members of the DSMB should have access to interim analyses 
of outcome data by treatment group. Exceptions may be made when the DSMB deems it 
appropriate. The reason and to whom the exceptions for access to interim analyses is granted 
will be documented in the Closed Session Report. DSMB members must maintain strict 
confidentiality concerning all privileged trial results ever provided to them. The DSMB should 
review data only by masked study group (such as X vs. Y rather than experimental vs. control) 
unless or until the DSMB determines that the identities of the groups are necessary for their 
decision-making. Whenever masked data are presented to the DSMB, the key to the group 
coding must be available for immediate unmasking.  
The DSMB will meet twice per year. The junior faculty investigator will attend these meetings 
and will be responsible for preparing and presenting up-to-date statistical reports on the 
progress of their trials. These reports will include data on recruitment, randomization, 
adherence, as well as statistical tests and special analyses requested by the DSMB. The 
Administrative Core will be responsible for organizing the annual in-person meeting and 
semiannual conference calls. They will put together data and materials submitted by junior 
faculty investigators and deliver them to DSMB members. The COBRE investigators will meet 
with the DSMB in the Open Session and not be present for the Closed Session. 
 
 

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