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.