Intensive Diabetes Therapy Has Long-Term Beneficial Effects On the Risk of Cardiovascular Disease

Intensive Diabetes Therapy Has Long-Term Beneficial Effects On the Risk of Cardiovascular Disease

December 23, 2005

By Sahar Bedrood B.S. and Asher Kimchi M.D.

Bethesda, MD - Type 1 Diabetes is associated with complications of many organ systems, such as the eyes and kidney. There is also a significant amount of cardiovascular damage as a result of untreated or long-term diabetes. While the mechanisms of this damage is still unclear, the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) Study Research Group from Bethesda, Maryland studied how intensive therapy vs. conventional therapy affected the long-term incidence of cardiovascular disease. The study, published in the December 22, 2005 issue of The New England Journal of Medicine found intensive diabetes therapy to be beneficial for cardiovascular health.

The original DCCT study consisted of 1441 patients with Type 1 Diabetes who were 13-40 years old at the time of randomization. The study determined a small number of cardiovascular events, thus a follow-up study, the EDIC, was conducted. It consisted of 1394 of the original patients. Lab studies included glycosylated hemoglobin level, fasting lipid levels, serum creatinine levels and serum albumin. Electrocardiograms were performed on all patients. Intensive therapy consisted of three or more daily injections of insulin or treatment with an external insulin pump, with dose adjustments based on at least four self-monitored glucose measurements per day.

Intensive therapy also included daily glucose goals of 70 to 120 mg per deciliter (3.9 to 6.7 mmol per liter) before meals and peak levels of less than 180 mg per deciliter (10.0 mmol per liter) after meals. Conventional therapy had no glucose goals beyond those needed to prevent symptoms of hyperglycemia and hypoglycemia and consisted of one or two daily injections of insulin.

During the mean 17 years of follow-up, 46 cardiovascular disease events occurred in 31 patients who had received intensive treatment in the DCCT, as compared with 98 events in 52 patients who had received conventional treatment. Intensive treatment reduced the risk of any cardiovascular disease event by 42 percent (95 percent confidence interval, 9 to 63 percent; P=0.02) and the risk of nonfatal myocardial infarction, stroke, or death from cardiovascular disease by 57 percent (95 percent confidence interval, 12 to 79 percent; P=0.02). The decrease in glycosylated hemoglobin values during the DCCT was significantly associated with most of the positive effects of intensive treatment on the risk of cardiovascular disease. Microalbuminuria and albuminuria were associated with a significant increase in the risk of cardiovascular disease, but differences between treatment groups remained significant (P0.05) after adjusting for these factors.

The relative reduction in the risk of nonfatal myocardial infarctions, stroke, and death from cardiovascular disease, of 57 percent — the most clinically compelling outcome — exceeds the reductions in risk achieved with other proven interventions, such as medications that lower cholesterol and blood pressure. The large reduction in the risk of cardiovascular events will further improve the projected long-term health and economic benefits of intensive therapy for diabetes. Thus, intensive therapy should be implemented as soon as possible for people with type 1 diabetes.

The Writing Committee — David M. Nathan, M.D. (chair), Patricia A. Cleary, M.S., Jye-Yu C. Backlund, M.S., Saul M. Genuth, M.D., John M. Lachin, D.Sc., Trevor J. Orchard, M.D., Philip Raskin, M.D., and Bernard Zinman, M.D. — vouches for the accuracy and integrity of the data.