title: No interaction of body mass index and smoking on diabetes mellitus risk in elderly women.
abstract: 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.
authors.affiliation: Nicotine Dependence Center, Primary Care Internal Medicine, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Michael W
authors.initials: MW
authors.lastname: Cullen
authors.forename: Jon O
authors.initials: JO
authors.lastname: Ebbert
authors.forename: Robert A
authors.initials: RA
authors.lastname: Vierkant
authors.forename: Alice H
authors.initials: AH
authors.lastname: Wang
authors.forename: James R
authors.initials: JR
authors.lastname: Cerhan
mesh_terms: 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