Strict glucose control in type 1 diabetes reduces the risk of atherosclerosis, a benefit that persists for years, according to a study published in the June 5, 2003, issue of The New England Journal of Medicine.
Since 1993, when the Diabetes Control and Complications Trial (DCCT) ended, researchers have known that intensive glucose control greatly reduces the eye, nerve, and kidney damage of type 1 diabetes. Now, researchers conclude, the benefits of tight control also extend to the heart.
"Intensive control is difficult to achieve and maintain, but its benefits are even greater than we realized," says study chair Saul Genuth, M.D., of Case Western University in Cleveland. "The earlier intensive therapy begins and the longer it can be maintained, the better the chances of reducing the debilitating complications of diabetes."
The DCCT was a multicenter study that compared intensive treatment with conventional management of blood glucose in 1,441 people with type 1 diabetes. Intensive treatment involves at least three insulin injections a day or an insulin pump and frequent self-monitoring of blood glucose. The goal of intensive treatment is to keep hemoglobin A1c (HbA1c), which reflects average blood sugar levels over 60 to 90 days, as close to normal (6 percent) as possible. Conventional treatment at the time of the DCCT consisted of one or two insulin injections a day with daily urine or blood glucose testing.
After six and one-half years of the DCCT, HbA1c levels averaged 7 percent in the intensively treated group and 9 percent in the conventionally treated group. When the DCCT ended, those who had been assigned to conventional treatment were encouraged to adopt intensive control and were shown how to do it. Researchers then began a long-term follow-up study of the participants, called the Epidemiology of Diabetes Interventions and Complications (EDIC) study.
The DCCT could not study atherosclerosis because the participants were relatively young, and heart disease takes years to develop. In 1994-1995 and again in 1998-2000, EDIC researchers used ultrasound to measure the thickness of participants' carotid arteries, the two blood vessels in the neck that carry blood from the heart to the brain. Carotid wall thickness reflects the amount of atherosclerosis, or plaque build-up, in the artery. The thicker the arterial wall the greater the risk of later heart attack and stroke. …