Aim: To examine the association between body mass index (BMI) and mortality among middle-aged people with diabetes in Japan.
Methods: A total of 3032 men and 1615 women, aged 40-69 years, with diabetes were analyzed. Cox proportional hazards models, adjusted for potential confounding factors, were used to estimate mortality hazard ratios (HRs) across BMI categories at the baseline.
Results: There were 1761 deaths during a mean follow-up period of 18.5 years. Increased all-cause mortality was observed at both ends of the BMI distribution; compared with the reference BMI category (23.0-24.9 kg/m2), the HRs were 1.25 (95% confidence interval [CI], 0.9997-1.56) in the lowest (14.0-18.9 kg/m2) and 1.36 (95% CI, 1.06-1.74) in the highest (30.0-39.9 kg/m2) categories (P = 0.001). Similar all-cause mortality trends were observed after excluding deaths within 3 years of follow-up, as well as for men and men who had ever smoked. While a similar non-linear pattern was observed for cancer-specific mortality, heart disease-specific mortality was only increased in the highest BMI category (HR, 1.86; 95% CI, 1.06-3.25).
Conclusion: This population-based prospective study demonstrated increased all-cause mortality at both ends of the BMI distribution among Japanese people with diabetes.
Keywords: Body mass index; Diabetes mellitus; Japan; Mortality; Prospective studies.
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