Risk of cardiovascular disease and mortality in overweight and obese patients with type 2 diabetes: an observational study in 13,087 patients

Aims/hypothesis The aim of this study of type 2 diabetic patients in the Swedish National Diabetes Register was to study the associations of BMI, overweight (BMI 25-29.9 kg/m(2)) and obesity (BMI >= 30 kg/m(2)) with cardiovascular disease in type 2 diabetes, as these associations have not previously been clarified. Methods Patients aged 30-74 years with no previous CHD or stroke (N=13,087) were followed for a mean of 5.6 years until 2003 for fatal or non-fatal CHD, stroke, cardiovascular disease (CHD or stroke) and total mortality. In total, 1,922 cardiovascular-disease events occurred, based on 64,864 person-years. Results The relative risks of CHD, stroke, cardiovascular disease and total mortality for a 5 unit increase in BMI at baseline were 15%, 11%, 13% and 27%, respectively, using Cox regression analysis, after adjusting for age, sex, diabetes duration, hypoglycaemic treatment and smoking (model 1), and were 9%, 4% (not significant), 7% and 20%, respectively, when adjusting also for HbA(1c), blood pressure, antihypertensive drugs, lipid-reducing drugs and microalbuminuria (model 2). Adjusted hazard ratios (model 1) for CHD, cardiovascular disease and total mortality with overweight were 1.27 (95% CI 1.09-1.48), 1.24 (1.09-1.41) and 1.16 (0.94-1.45), respectively, and 1.49 (1.27-1.76), 1.44 (1.26-1.64) and 1.71 (1.36-2.14) with obesity, as compared with normal weight. Significant hazard ratios were attenuated when adjusted according to model 2. For a 1 unit increase in BMI during follow-up, the relative risk of CHD (model 2) was 1.13 (1.04-1.23; p=0.005). Conclusions/interpretation Both overweight and obesity independently increased the risk of CHD and cardiovascular disease in patients with type 2 diabetes. The CHD risk was higher with increasing BMI than with stable or decreasing BMI during the study.