Body Mass Index and the Risk of All-Cause Mortality Among Patients With Type 2 Diabetes Mellitus

Abstract

Background— Several prospective studies have evaluated the association between body mass index (BMI) and death risk among patients with diabetes mellitus; however, the results have been inconsistent. Methods and Results— We performed a prospective cohort study of 19 478 black and 15 354 white patients with type 2 diabetes mellitus. Cox proportional hazards regression models were used to estimate the association of different levels of BMI stratification with all-cause mortality. During a mean follow-up of 8.7 years, 4042 deaths were identified. The multivariable-adjusted (age, sex, smoking, income, and type of insurance) hazard ratios for all-cause mortality associated with BMI levels (18.5–22.9, 23–24.9, 25–29.9, 30–34.9 [reference group], 35–39.9, and ≥40 kg/m 2 ) at baseline were 2.12 (95% confidence interval [CI], 1.80–2.49), 1.74 (95% CI, 1.46–2.07), 1.23 (95% CI, 1.08–1.41), 1.00, 1.19 (95% CI, 1.03–1.39), and 1.23 (95% CI, 1.05–1.43) for blacks and 1.70 (95% CI, 1.42–2.04), 1.51 (95% CI, 1.27–1.80), 1.07 (95% CI, 0.94–1.21), 1.00, 1.07 (95% CI, 0.93–1.23), and 1.20 (95% CI, 1.05–1.38) for whites, respectively. When stratified by age, smoking status, patient type, or the use of antidiabetic drugs, a U-shaped association was still present. When BMI was included in the Cox model as a time-dependent variable, the U-shaped association of BMI with all-cause mortality risk did not change. Conclusions— The present study indicated a U-shaped association of BMI with all-cause mortality risk among black and white patients with type 2 diabetes mellitus. A significantly increased risk of all-cause mortality was observed among blacks with BMI <30 kg/m 2 and ≥35 kg/m 2 and among whites with BMI <25 kg/m 2 and ≥40 kg/m 2 compared with patients with BMI of 30 to 34.9 kg/m 2 .