The Effectiveness of Smoking Cessation in Prediabetic Smokers
Phase: NA
Conditions: Diabetes Mellitus, Cigarette Smoking, Prediabetes
Sponsor: National Taiwan University Hospital

1st version: August 20, 2013; latest version: November 08, 2021                                    Page 1 
Study Protocol and Statistical Analysis Plan 
 
NCT01926041 
 
The Effectiveness of Smoking 
Cessation in Prediabetic Smokers 
 
 

1st version: August 20, 2013; latest version: November 08, 2021                                    Page 2 
Introduction 
Post-cessation weight gain (PCWG) facilitates short-term type 2 diabetes (T2D) risk in 
prediabetic smokers in the absence of complementary measures. Little existing literature has 
explored the long-term effect of smoking cessation combined with PCWG restriction on T2D 
development. Primary care physicians should fight smoking and obesity together to prevent T2D 
and progression of its relevant comorbidities such as nonalcoholic fatty liver disease (NAFLD). 
This project pioneered the Fight Tobacco and Stay Fit (FIT2) program, which integrated smoking 
cessation therapy with individualized behavior coaching in diet and physical activity for PCWG 
restriction in prediabetic smokers. 
 
Study Objectives 
1. Glycemic: To investigate whether glycemic outcomes would be improved by the FIT2 program 
(combining smoking cessation therapy and PCWG restriction for a complete 16 weeks) and the 
post-program abstinence, respectively 
Aim 1-(1): To test the hypothesis that the FIT2 program would reduce long-term T2D risk 
determined in December 2020 (primary outcome) and at 10 years. 
Aim 1-(2): To test the hypothesis that maintaining post-program abstinence would reduce 10-
year T2D risk. 
Aim 1-(3): To test the hypothesis that the FIT2 program would facilitate long-term probability 
of regression to normoglycemia determined in December 2020 and at 10 years. 
Aim 1-(4): To test the hypothesis that maintaining post-program abstinence would facilitate a 
10-year probability of regression to normoglycemia. 
Aim 1- (5) To explore whether HbA1c changes at 6 and 12 months would be affected by FIT2 
program and the post-program abstinence, respectively. 
 
2. Extraglycemic: To explore whether extraglycemic endpoints would be improved by the FIT2 
program and the post-program abstinence, respectively. 
Aim 2-(1): To test the hypothesis that the FIT2 program and maintaining post-program 
abstinence would reduce serial and 10-year NAFLD progression. 
Aim 2-(2): To test the hypothesis that the FIT2 program and maintaining post-program 
abstinence would reduce major adverse cardiac events at 10 years. 
Aim 2-(3): To test the hypothesis that the FIT2 program and maintaining post-program 
abstinence would reduce serial and 10-year chronic kidney disease progression. 
Aim 2-(4): To test the hypothesis that the FIT2 program and maintaining post-program 
abstinence would reduce malignancy incidence at 10 years. 
Aim 2-(5): To test the hypothesis that the FIT2 program and maintaining post-program 
abstinence would reduce all-cause mortality at 10 years. 
 
 
 

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Methods 
Participants 
We expect to recruit prediabetic smokers receiving medical care at two hospitals in 
Northern and Central Taiwan, where a systematic identification system has been applied to 
classify the tobacco addiction status of every patient in outpatient clinics.1 This study invites 
identified current smokers to undergo screening tests between August 2013 to January 2017. 
Included are participants with prediabetes aged 30 to 75 years who have smoked ≥10 
cigarettes per day for at least six months. Prediabetic participants are those who have repeated 
results for any of the following parameters: 1) plasma glucose levels 5.6–6.9 mmol/L (100–
125 mg/dL) in the fasting state; 2) plasma glucose levels 7.8–11.0 mmol/L (140–199 mg/dL) 
two hours after a 75-g oral glucose load; and 3) glycated hemoglobin (HbA1c) levels 39–46 
mmol/mol (5.7–6.4%), in the absence of antidiabetic drugs.2 Excluded are those with a pre-
existing diagnosis of T2D; thyroid disease; an acute cardiac condition within three months; 
acute renal failure; chronic glomerulonephritis; polycystic kidney disease; decompensated 
liver disease; a mental health disorder ever diagnosed by psychiatrists; or malignancy; as well 
as those with alcohol consumption exceeding 70 g per week for women or 140 g per week for 
men; women who were pregnant or breast-feeding; or those currently taking antidiabetic 
drugs, smoking cessation medications, steroids, lithium or antipsychotics. Information about 
tobacco use, alcohol consumption, physical activity, depression, sleep quality, personal 
medical histories, and current medications is collected through standardized personal 
interviews and medical records. The study protocol has been approved by the National Taiwan 
University Hospital Research Ethics Committee (No. 201303041RINB). All participants 
should provide written informed consent. This study is conducted according to the Declaration 
of Helsinki and has been pre-registered at ClinicalTrials.gov (NCT01926041). 
 
Sample Size Estimation, Recruitment, Assignment, Follow-up, and Analytic Design 
We estimated to recruit at least 596 prediabetic smokers, 33% (199) of whom join the 
FIT2 program, to reach 90% power and a two-sided 95% CI for the detection of a 50% risk 
reduction, assuming 30% as the risk of incident T2D during follow-up in the usual care 
group.3 The assignment of this trial is based on shared decision-making (Figure 1). At 
baseline, all eligible prediabetic smokers are asked if they would like to join the FIT2 program 
or just receive usual care. Beginning at enrollment, the smoking status, breath carbon 
monoxide levels, anthropometric indices, and blood tests are recorded every six months. The 
intention-to-treat analysis is performed to compare the FIT2 program participants with those 
receiving usual care. The modified per-protocol analysis is adopted to compare participants 
with documented abstinence at prespecified study ends (e.g., December 2020 or 10 years) 

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with the controls. 
 
The FIT2 Program and Post-Program Abstinence 
The FIT2 program is a 16-week program that combined pharmacotherapy for smoking 
cessation with individualized counseling focused on both smoking cessation and weight-
control techniques. Behavioral counseling in tobacco cessation techniques is delivered to 
every FIT2 participant involving one session per week.4 The pharmacotherapy in the FIT2 
program is a 16-week varenicline course, which conforms to real-practice government 
regulations in Taiwan. The varenicline is subsidized by the tobacco health welfare surcharge 
and its prescription adheres to manufacturer's directions and regulations by the Health 
Promotion Administration, Ministry of Health and Welfare, Taiwan (www.hpa.gov.tw). It is 
initiated at 0.5 mg once daily for the first three days, increased to 1 mg once daily from day 4 

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to day 7, and then increased to 1 mg varenicline twice daily from day 8 to the end of 16 
weeks. After 16 weeks, varenicline is no more administered. During the therapy course, 
physicians could adjust the varenicline dosages according to tolerability. Participants joining 
the FIT2 program are encouraged either to set their quit day 8 days after starting the 
varenicline; or to freely choose quit day at any time between Days 8 and 35. Nicotine 
replacement therapies are prohibited during the study period. 
In addition to varenicline prescription and smoking cessation counseling covered in 
conventional smoking cessation services, the FIT2 program also offers individualized weekly 
diet and physical activity coaching to restrict PCWG. The counseling sessions allow 
opportunities to identify obstacles to lifestyle change and to discuss approaches with a 
professional panel of dietitians and certified personal trainers. The dietitians instruct the FIT2 
participants to choose minimally processed, whole grains, vegetables, whole fruits, nuts, 
healthful sources of protein, and plant oils; rather than sugared beverages, refined grains, 
potatoes, red and processed meats, and other highly processed foods. The FIT2 participants 
are also encouraged to do at least 150 minutes of moderate-intensity (3.0-6.0 metabolic 
equivalents) aerobic physical activity throughout the week. Emphasis is placed on checking 
the weekly diary for body weight, food, and physical activity through protected cellphone 
messages between participants and the assigned panel professionals. For those who gain 
weight, more intensive ways of calorie restriction and physical activity (at least 300 minutes 
of moderate-intensity aerobic physical activity per week) will be instructed. 
Post-program abstinence status is recorded weekly during the first 16 weeks and then 
every 6 months until 10 years by self-reported 7-day point prevalence of abstinence and a 
breath carbon monoxide level of less than 6 ppm. Post-program quitters are those who quit 
successfully at 16 weeks after the FIT2 program and maintain their non-smoking status at 
prespecified study ends (e.g., December 2020 or 10 years) (achieving post-program 
abstinence). For the modified per-protocol analysis, participants who fail to keep quit after the 
FIT2 program are reassigned to the control group. 
 
Usual Care and Control 
Usual care is provided for prediabetic smokers who decide not to join the FIT2 program. 
Usual care comprises interpretation of laboratory results and encouragement to quit smoking 
and initiate a therapeutic lifestyle change for T2D prevention at each visit. In the modified per-
protocol analysis, the control group contains participants joining the FIT2 program who fail to 
achieve post-program abstinence and all participants receiving usual care, including those who 
quit smoking on their own (Figure 1). 
 
Outcome Measures (refer to the section “Study Objectives”) 
The primary outcome is new-onset T2D through December 2020, defined as random 
plasma glucose ≥11.1 mmol/L (200 mg/dL) with hyperglycemic symptoms or repeated results 
in at least one of the following parameters: 1) plasma glucose levels ≥7.0 mmol/L (126 

1st version: August 20, 2013; latest version: November 08, 2021                                    Page 6 
mg/dL) in the fasting state; 2) plasma glucose levels ≥11.1 mmol/L (200 mg/dL) two hours 
after a 75-g oral glucose load; 3) HbA1c levels ≥48 mmol/mol (6.5%) 2; or currently taking 
medications for physician-diagnosed T2D. The other prespecified glycemic outcome is new-
onset T2D at 10 years (determined between 2022 and 2026). We also determine the 
probability of regression to normoglycemia in December 2020 and at 10 years (between 2022 
and 2026). Participants who regress to normoglycemia should meet all the following 
conditions for more than six months and maintain such status until the prespecified study end: 
1) plasma glucose levels <5.6 mmol/L (100 mg/dL) in the fasting state; 2) plasma glucose 
levels <7.8 mmol/L (140 mg/dL) two hours after a 75-g oral glucose load; or 3) HbA1c levels 
<39 mmol/mol (5.7%), in the absence of antidiabetic drugs. The investigators also explore 
whether HbA1c changes at 6 and 12 months would be affected by FIT2 program and the post-
program abstinence, respectively. 
The following extraglycemic endpoints are also secondary outcomes (determined between 
2022 and 2026). The steatohepatitic outcome is serial and 10-year NAFLD progression. Each 
participant is evaluated using FIB-4 scores, BARD scores, liver stiffness measurement (LSM) 
at baseline, every six months, and at 10 years. TE (FibroScan) for liver LSM is performed in 
fasting condition.5-7 The measurement depth is between 25 and 65 mm using the M-probe 
(standard probe) and between 35 and 75 mm using the XL-probe. LSM is stopped when 10 
valid measurements are recorded with the result (kilo Pascal, kPa) expressed as the median of 
these valid measurements. The same machine can be used to determine whether steatosis is 
present after the CAP value is determined. We will also obtain FIB-4 scores 
(www.mdcalc.com/fibrosis-4-fib-4-index-liver-fibrosis) and BARD scores 
(www.mdcalc.com/bard-score-nafld-fibrosis) at 10 years for every participant, as described in 
the Introduction section. In addition, a low 10-year composite score is defined as 
simultaneously reaching a FIB-4 score <1.45, a BARD score 0-1, and LSM <7 kPa. The 
cardiovascular outcome is major adverse cardiac events at 10 years, defined as events of 
cardiovascular death, non-fatal myocardial infarction, and non-fatal stroke diagnosed by 
specialists according to medical records. The renal outcome is serial and 10-year chronic 
kidney disease progression, defined as progression to macroalbuminuria [urinary albumin-to-
creatinine ratio (UACR), >300 mg of albumin per gram of creatinine] for ≥ 3 months, or 
decrease in estimated glomerular filtration rate (eGFR) to <60mL/min/1.73 m2 for ≥ 3 
months, as calculated by the four-variable Modification of Diet in Renal Disease (MDRD) 
formula, and incident albuminuria for ≥ 3 months. Incident malignancies based on medical 
records are accessed at 10 years, confirmed by national cancer registry system. All-cause 
mortality is ascertained at 10 years by computer linkage to the national death registry (death 
certificates were created by the Ministry of Health and Welfare, Taiwan) using ID numbers 
and these death certificates have been validated. 
 
Interview, Anthropometric Indices, Laboratory Tests, Covariates, and Confounders 
We review the medical records after getting informed consent. Through standardized 

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personal interviews, the investigators collect information about tobacco use, alcohol 
consumption, eating habits, physical activity levels, depression scale, circadian rhythm, sleep 
quality, and current medications. Body height and weight are measured using a standard 
stadiometer, and body mass index is calculated. Blood pressure is measured with an electronic 
sphygmomanometer while the patient is seated after resting for at least five minutes. 
Hypertension is defined as a history of hypertension according to medical records or 
repeatedly having office blood pressure ≥140/90 mmHg or home blood pressure ≥135/85 
mmHg. Each participant undergoes laboratory testing after fasting for at least ten hours. The 
blood tests are performed every 6 months by the central lab of a tertiary center. The items 
include plasma glucose and HbA1c levels, serum fasting insulin levels, complete blood count 
(CBC & platelet), ferritin, ALT, AST, total/direct bilirubin, LDL-C, HDL-C, TG, high 
sensitivity C-Reactive Protein (hs-CRP), urine albumin to creatinine ratio (UACR), and 
creatinine levels. The estimated glomerular filtration rate is calculated using the four-variable 
version of the Modification of Diet in Renal Disease Study equation for Chinese Patients.8 
Dyslipidemia is defined as the presence of at least one of the following conditions: a plasma 
triglyceride level ≥1.70 mmol/L (150 mg/dL), a serum low-density lipoprotein level ≥3.37 
mmol/L (130 mg/dL), a serum high-density lipoprotein level <1.04 mmol/L (40 mg/dL) in 
men or <1.29 mmol/L (50 mg/dL) in women, or history of dyslipidemia according to medical 
records. Insulin resistance scores are determined by the homeostasis model assessment of 
insulin resistance (HOMA-IR),9 as calculated by the following formula: HOMA-IR score = 
fasting insulin (μIU/mL) × fasting glucose (mg/dL)/405. Participants are categorized as 
insulin resistant if the HOMA-IR was 2.5 or higher.10,11 The triglyceride glucose (TyG) index 
is calculated by the logarithm of fasting triglyceride × fasting glucose/2 to account for a 
surrogate marker of insulin resistance.12 Serological tests include serum hepatitis B surface 
antigen, serum antibody to hepatitis C virus, and hepatitis B e antigen, determined via a 
microparticle enzyme immunoassay (Abbott Laboratories, Illinois, USA). 
The investigators collect the parameters of physical activity level, depression scale score, 
and sleep quality at baseline. The physical activity level within the last week is calculated as 
the average daily energy expenditure in Kcal/day by the following formula: Sum of 7-day 
task-specific metabolic equivalent values (MET, Kcal/kg/hour; 1 for sleeping, 1.5 for light-
intensity activities, 4 for moderate-intensity activities, 6 for vigorous-intensity activities, and 
10 for very-vigorous-intensity activities) multiplied by task-specific hours multiplied by body 
weight (kg) and then divided by 7 days.13 Being physically active is determined if the energy 
expenditure was over the third quartile. The depression score for one week is obtained using 
the Center for Epidemiologic Studies Depression Scale,14 Chinese version (20 sub-items; '0', 
'1', '2', and '3' for each sub-item; summed global score from 0 to 60). Depressive disorder is 
suspected if the score ≥16, and the patient was referred to a psychiatrist. The sleep quality 
score for one month is obtained using the Pittsburgh Sleep Quality Index,15 Chinese version [7 
components; '0 (no difficulty)' to '3 (severe difficulty)' for each component; summed global 
score from 0 to 21]. Sleep disturbance is considered if the score was six or higher. 

1st version: August 20, 2013; latest version: November 08, 2021                                    Page 8 
 
Statistical analyses 
For the descriptive analyses, values are presented as either numbers (percentages) or mean 
± standard deviations. For the univariate analyses, categorical data are compared by the χ2 test 
or Fisher's exact test. Continuous variables are compared using the two-sample Student's t-
test. Statistical significance levels were determined by two-tailed tests (P<0.05). 
We will perform Cox proportional hazards regression and logistic regression analyses to 
explore the associations of the FIT2 program with development of all prespecified outcomes 
in intention-to-treat analyses. Kaplan-Meier failure plots of T2D risks of the two groups are 
drawn. We assumed missing values over time were missing at random and performed listwise 
deletion. We will test the assumption of proportional hazards. Logistic regression via GEE 
approach is utilized to evaluate the serial associations of the FIT2 program with NAFLD and 
CKD progression. In modified per-protocol analyses, the associations between achieving post-
program abstinence and glycemic and extraglycemic outcomes will be explored using multiple 
logistic regression models. All of the abovementioned statistical analyses summarized in 
Table 2 and will be performed with SAS software version 9.4 (SAS Institute Inc., Cary, NC, 
USA).  
 
Table 2. Statistical strategies for glycemic and extraglycemic outcomes in this study 
    ITT, intention-to-treat; PP, per-protocol. 
 
Outcomes 
Cox regression 
Logistic regression 
T2D risk: ITT analysis 
Actual time 
At 10 years 
T2D risk: modified PP analysis 
N/A 
At 10 years 
Regression to normoglycemia: ITT analysis 
Actual time 
At 10 years 
Regression to normoglycemia: modified PP analysis 
N/A 
At 10 years 
NAFLD progression: ITT analysis 
N/A 
Serially (GEE) and at 10 years 
NAFLD progression : modified PP analysis 
N/A 
At 10 years 
Major adverse cardiac events: ITT analysis 
Actual time 
At 10 years 
Major adverse cardiac events: modified PP analysis 
N/A 
At 10 years 
CKD progression: ITT analysis 
Actual time 
Serially (GEE) and at 10 years 
CKD progression: modified PP analysis 
N/A 
At 10 years 
Incident malignancies: ITT analysis 
Actual time 
At 10 years 
Incident malignancies: modified PP analysis 
N/A 
At 10 years 
All-cause mortality: ITT analysis 
Actual time 
At 10 years 
All-cause mortality: modified PP analysis 
N/A 
At 10 years 

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