Relationship between body mass index, antidiabetic agents, and midterm mortality in patients with both type 2 diabetes mellitus and acute coronary syndrome

Background-The aim of this study was to determine the influence of various antidiabetic therapies on the relationship between body mass index and all-cause mortality in patients with diabetes mellitus and acute coronary syndrome. Methods and Results-This was a prospective, observational study comprising 1193 patients diagnosed with type 2 diabetes mellitus and acute coronary syndrome. The patients were stratified into 4 body mass index categories, and their mortality rates were compared using time-dependent Cox regression analysis using normal weight (body mass index, 18.5-23.9) as the reference. Subsequently, the influence of antidiabetic therapies on the association between BMI and mortality were analyzed. Seventy-four patients (6.2%) died over 2 years of follow-up. The mortality rate was lowest in the class I obese group (3.35%) and highest in the normal-weight group (9.67%). After adjusting for covariates, class I obesity paradoxically remained significantly protective against mortality compared with normal weight (hazard ratio, 0.141; P=0.049); interaction term analysis showed that insulin therapy influenced this “obesity paradox” (P=0.045). When the patients were stratified by insulin use, the protective effect of obesity disappeared in the insulin-treated patients but persisted in the non-insulin-treated patients. Conclusions-In patients with type 2 diabetes mellitus and acute coronary syndrome, the relationship between body mass index and mortality rate is U-shaped, with class I obesity representing the nadir and normal weight the peak. The protective effect of obesity disappeared in patients treated with insulin.