No interaction of body mass index and smoking on diabetes mellitus risk in elderly women.
OBJECTIVE
We sought to assess the interaction of smoking and body mass index (BMI) on diabetes risk.


METHODS
We analyzed data from a community-based prospective cohort of 41,836 women from Iowa who completed a baseline survey in 1986 and five subsequent surveys through 2004. The final analysis included 36,839 participants.


RESULTS
At baseline (1986), there were 66% never smokers, 20% former smokers, and 14% current smokers. Subjects represented 40% normal weight, 38% overweight, and 22% obese individuals. Compared to normal weight women, the hazard ratio (HR) for diabetes was increased in overweight (HR 1.96; 95% CI 1.75-2.19) and obese subjects (HR 3.58; 95% CI 3.19-4.02). The hazard ratio for diabetes increased in a dose-dependent manner with smoking intensity. Compared to never smokers, former smokers had a higher risk for diabetes (HR 1.22; 95% CI 1.11-1.34). Among current smokers, the hazard ratio for diabetes was 1.21 (95% CI 0.95-1.53) for 1-19 pack-year smokers, 1.33 (95% CI 1.12-1.57) for 20-39 pack-year smokers, and 1.45 (95% CI 1.23-1.71) for > or =40 pack-year smokers. Similar trends were observed when the results were stratified by BMI. A test of interaction between BMI and smoking on diabetes risk was not statistically significant.


CONCLUSIONS
Our findings suggest that smoking increases diabetes risk through a BMI-independent mechanism.
Cullen
Michael W
MW
Nicotine Dependence Center, Primary Care Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA.
Ebbert
Jon O
JO
Vierkant
Robert A
RA
Wang
Alice H
AH
Cerhan
James R
JR
D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000453:epidemiology / Q000209:etiology*; D004032:Diet; D005260:Female; D015438:Health Behavior; D006801:Humans; D007484:Iowa / Q000453:epidemiology; D008875:Middle Aged; D009765:Obesity; D011446:Prospective Studies; D018570:Risk Assessment; D012907:Smoking / Q000453:epidemiology*; D011795:Surveys and Questionnaires