Major cardiovascular disease is four times more common in men and eight times more common in women with type 1 diabetes, compared with nondiabetic men and women, Sabita S. Soedamah-Muthu, Ph.D., reported.
Type 1 diabetes also dramatically increases risks for fatal cardiovascular disease, major coronary heart disease, stroke, coronary revascularization, and acute coronary events, even in the modern era of emphasis on intensive glycemic control, said Dr. Soedamah-Muthu of the Royal Free and University College, London.
The first large, controlled study to evaluate absolute and relative risks of both morbidity and mortality related to cardiovascular disease in type 1 diabetics found that absolute risk levels seen in the nondiabetic population by age 60 appear in men with type 1 diabetes around ages 45–50 years and even earlier in women, said Dr. Soedamah-Muthu and associates (Diabetes Care 2006;29:798–804).
The investigators analyzed data from the General Practice Research Database, a large primary-care database from a network of 603 practices. They compared data for 7,479 patients with type 1 diabetes with data for 38,116 nondiabetic control patients, with five controls matched to each diabetic patient by age and sex.
The risk for fatal cardiovascular disease was increased 6-fold in men and 12-fold in women with type 1 diabetes, compared with controls of the same sex. The risk for major coronary heart disease was quadrupled in men and 10 times higher in women with type 1 diabetes, compared with nondiabetic patients. Strokes, both fatal and nonfatal, were four times more common in men and five times more common in women with type 1 diabetes.
Coronary revascularizations were performed 5 times more often in men and 17 times more often in women with type 1 diabetes, compared with controls. The risk for acute coronary events tripled in men and was eight times higher in women with type 1 diabetes, compared with nondiabetic controls.
It is unclear how much of these increased risks might be explained by the long duration of glycemic exposure. The average duration of diabetes in the study was 15 years. The causes of higher risks in women also are unclear.
“Whatever its basis, the ongoing dramatic elevation in CVD [cardiovascular disease] risk in type 1 diabetic patients, especially diabetic women, needs to be emphasized to clinicians, as the relatively good lipid profile of type 1 diabetic patients without renal disease could lead to their CVD risk being underappreciated,” Dr. Soedamah-Muthu wrote.
Clinicians should evaluate patients with type 1 diabetes for potential preventive interventions such as statin therapy starting at 45 years of age, possibly younger, the investigators suggested. Because traditional risk factors for cardiovascular disease may be less effective in identifying risk in diabetic than in nondiabetic patients, it might be reasonable to consider imaging to look for early cardiovascular disease in addition to measuring traditional risk factors in patients with type 1 diabetes, they added.
The absolute risk for cardiovascular disease at ages 45–55 was 11/1,000 person-years in men with type 1 diabetes and 4/1,000 person-years in male controls. In women aged 45–55 years, the absolute risk for cardiovascular disease was 10/1,000 person-years in those with type 1 diabetes and 1/1,000 person-years in controls. The hazard ratio for major cardiovascular disease among diabetics in that age group, compared with controls, was 3 for men and 10 for women.
The higher risks for cardiovascular disease in women could not be attributed to a greater propensity to diagnose or treat cardiovascular disease in diabetic women, the investigators said.