A new study of adult diabetes patients links chronic hyperglycemia (high blood sugar levels) with an increased risk for cardiovascular disease, the most common cause of death among people with diabetes. Researchers at the Johns Hopkins University Schools of Medicine and Public Health performed a meta-analysis of observational studies. They pooled adjusted relative risk estimates for the relationship between glycosylated hemoglobin (which reflects long-term glycemic control) and cardiovascular disease events (coronary heart disease and stroke). Three studies involved 1,688 people with type 1 (insulin-dependent) diabetes, and 10 studies involved 7,435 people with type 2 (non-insulin-dependent) diabetes.
The pooled relative risk for coronary heart disease and stroke among people with type 2 diabetes was a moderate 18 percent higher for each 1 percentage point increase in glycosylated hemoglobin, and for people with type 1 diabetes, it was 15 percent higher for coronary heart disease for each 1 percentage point increase in glycosylated hemoglobin. In some studies, this association seemed to be independent of other known risk factors for cardiovascular disease. No studies estimated the risk of stroke by level of glycosylated hemoglobin for type 1 diabetes.
The few studies suggested the possibility of an even stronger association between glycosylated hemoglobin levels and peripheral arterial disease, with increased relative risks of 32 percent for people with type 1 diabetes and 28 percent for people with type 2 diabetes for each 1 percentage point increase in glycosylated hemoglobin. Although this analysis suggests that improvements in glycosylated hemoglobin level might translate into reductions in cardiovascular events, confirmation from randomized trials is necessary, conclude the researchers. Their work was supported in part by the Agency for Healthcare Research and Quality (contract 290-97-0006).
See "Meta-analysis: Glycosylated hemoglobin and cardiovascular disease in diabetes mellitus," by Elizabeth Selvin, M.P.H., Spyridon Marinopoulos, M.D., M.B.A., Gail Berkenblit, M.D., Ph.D., and others, in the September 2004 Annals of Internal Medicine 141, pp. 421-431.