The Effectiveness of Smoking Cessation in Prediabetic Smokers

Participants:

We expect to recruit study participants at National Taiwan University Hospital and its Yunlin branch, where a systematic identification system has been applied to classify the tobacco addiction status of every patient in outpatient clinics. This study invites identified current smokers to undergo screening tests between August 2013 to January 2017. All participants should give informed consent, with personal data protected. Only individuals aged 30 to 75 years are included. A history of diabetes, hypertension, Fagerström test for nicotine dependence, alcohol consumption, physical activity, depression, sleep quality, and current medications is collected through standardized personal interviews. Prediabetic participants are those who repeatedly have either of the following: 1) plasma glucose 100 to 125 mg/dL (5.6 to 6.9 mmol/L) in the fasting state; 2) plasma glucose 140 to 199 mg/dL (7.8 to 11.0 mmol/L) two hours after a 75-g oral glucose load; 3) glycosylated hemoglobin (A1C) 5.7% to 6.4%, in the absence of diabetic medications. Prediabetic participants who smoke ≥10 CPD for at least 6 months are classified as prediabetic smokers. Excluded are those with existing diagnosis of DM, thyroid diseases, acute cardiac conditions within 3 months, acute renal failure, chronic glomerulonephritis, polycystic kidney disease, mental health disorders ever diagnosed by psychiatrists, pregnancy, breast-feeding, malignancy; or current use of diabetic medications, 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 was approved by the National Taiwan University Hospital Research Ethics Committee.

Sample size estimation We estimate to recruit at least 596 prediabetic smokers, 33% (199) of whom decide to join the intervention, 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.

Assignment, prospective follow-up, and analytic design The assignment of this trial is based on shared decision-making. At baseline, all eligible prediabetic smokers are asked if they would like to join the Fight Tobacco and Stay Fit (FIT2) program or just receive usual care. Beginning at enrollment, the smoking status, breath carbon monoxide levels, anthropometric indices, automated office and home blood pressures, and blood tests were recorded every six months. The intention-to-treat analysis is performed among all participants joining the FIT2 program and receiving usual care. The modified per-protocol analysis is adopted to compare participants with documented abstinence at prespecified study ends (e.g., 10 years) with the controls.

The FIT2 program and post-program abstinence: