High‐Intensity Cigarette Smoking Is Associated With Incident Diabetes Mellitus In Black Adults: The Jackson Heart Study

BACKGROUND Previous reports on whether smoking is associated with insulin resistance and diabetes mellitus have yielded inconsistent findings. We aimed to evaluate the relationship between cigarette smoking and incident diabetes mellitus in the Jackson Heart Study. METHODS AND RESULTS Jackson Heart Study participants enrolled at baseline without prevalent diabetes mellitus (n=2991) were classified by self-report as current smokers, past smokers (smoked ≥400 cigarettes/life and no longer smoking), or never smokers. We quantified smoking intensity by number of cigarettes smoked daily; we considered ≥20 cigarettes per day (1 pack) "high-intensity." We defined diabetes mellitus as fasting glucose ≥126 mg/dL, hemoglobin A1c ≥6.5% or International Federation of Clinical Chemistry units HbA1c 48 mmol/mol, or use of diabetes mellitus medication. We estimated the adjusted associations of smoking status, intensity, and dose (pack-years) with incident diabetes mellitus using Poisson regression models. At baseline there were 361 baseline current (1-10 cigarettes per day [n=242]; ≥20 [n=119]), 502 past, and 2128 never smokers. From Visit 1 to Visit 3 (mean 8.0±0.9 years), 479 participants developed incident diabetes mellitus. After adjustment for covariates, baseline current smokers who smoked less than a pack/d and past smokers had similar rates of incident diabetes mellitus compared with never smokers (incidence rate ratios 1.04, 95% confidence interval, 0.69-1.58 and 1.08, 95% confidence interval, 0.82-1.42, respectively). Baseline current high-intensity smokers had a 79% (95% confidence interval, 1.14-2.81) higher incidence of diabetes mellitus compared with never smokers. Smoking dose (per 10 pack-years) was also associated with a higher incidence of diabetes mellitus (incidence rate ratios 1.10, 95% confidence interval, 1.03-1.19) in adjusted models. CONCLUSIONS High-intensity cigarette smoking and smoking pack-years are associated with an increased risk of developing diabetes mellitus in blacks.