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/m²) and obesity (BMI ≥ 30 kg/m²) 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.