Similarity of the impact of type 1 and type 2 diabetes on cardiovascular mortality in middle-aged subjects

OBJECTIVE - To compare the risk of cardiovascular disease (CVD) death and the impact of hyperglycemia on the risk of CVD mortality associated with type I diabetes to that associated with type 2 diabetes. RESEARCH DESIGN AND METHODS - The study comprised 173 participants with type 1 diabetes, 834 participants with type 2 diabetes, and 1,294 nondiabetic participants, aged 45-64 years at baseline and free of CVD. The age of onset of diabetes was >30 years in both diabetic groups. RESULTS - During an 18-year follow-up, 86 participants with type 1 diabetes, 567 participants with type 2 diabetes, and 252 nondiabetic participants died. CVD mortality rates per 1,000 person-years were 23.1 (95% CI 16.9-31.9) in type 1 diabetic, 35.3 (30.8-40.4) in type 2 diabetic, and 4.6 (3.8-5.7) in nondiabetic participants. Adjusted hazard ratios for CVD mortality in participants with type 1 diabetes versus no diabetes was 3.6 (95% Cl 2.2-5.7) in men and 13.3 (6.9-22.5) in women and in participants with type 2 diabetes versus no diabetes 3.3 (2.5-4.5) in men and 10.1 (6.7-17.4) in women. An increment of I unit (%) of GHb increased CVD mortality by 52.5% (95% C1 28.4-81.3) in type 1 diabetic subjects and by 7.5% (4.3-10.8) in type 2 diabetic participants. CONCLUSIONS - The impact of type 1 and type 2 diabetes on CVD mortality was similar. The effect of increasing hyperglycemia on the risk of CVD mortality was more profound in type I than in type 2 diabetic subjects.