The findings are based on a follow-up study of patients who took part more than a decade ago in the Diabetes Control and Complications Trial (DCCT), a major clinical study funded by the National Institutes of Health (NIH).

Reported in 1993, those earlier results showed that intensive glucose control prevents or delays the eye, nerve and kidney complications of type 1 diabetes. At the time, however, researchers had not followed participants long enough to know whether tight control also lowered the risk of heart attack and stroke.

"Heart disease currently is about 10 times more common in people with type 1 diabetes than in people who don't have diabetes. Now we know that intensive glucose control decreases the likelihood of heart and blood vessel complications in people with type 1 diabetes," said William Sivitz, M.D., Hospitals an Clinics endocrinologist and professor of internal medicine in the UI Roy J. and Lucille A. Carver College of Medicine, an investigator for the DCCT study and the principal investigator for UI participation in the follow-up study.

Nearly 21 million people in the United States--approximately seven percent of the population--have diabetes, the most common cause of blindness, kidney failure and amputations in adults and a major cause of heart disease and stroke. At least 65 percent of people with diabetes will die from a heart attack or stroke, yet two of every three people with diabetes are unaware of their increased risk.

"Maintaining tight control is challenging, but it provides huge benefits both in the short- and long-term. Intensive control should begin as soon as possible and be maintained as long as possible," said Sivitz, who also is a researcher and physician with the Veterans Affairs Iowa City Health Care System.

Type 1 diabetes accounts for five to 10 percent of all diagnosed cases of diabetes in the United States. This form of diabetes usually develops in children and young adults. People with type 1 diabetes usually need three or more insulin injections a day or an insulin pump to maintain the blood glucose level shown to prevent or delay long-term complications.

In results reported today, tight glucose control lowered the risk of a cardiovascular disease (CVD) event by 42 percent and the risk of a serious CVD event, including heart attack or stroke, by 58 percent.

The earlier study compared intensive management of blood glucose to conventional control in 1,441 people with type 1 diabetes. Patients aged 13 to 39 took part in that six-year trial between 1983 and 1989.

At the time, conventional treatment consisted of one or two insulin injections a day with daily urine or blood glucose testing. Participants randomly assigned to intensive treatment were asked to keep glucose levels as close to normal as possible with at least three insulin injections a day or an insulin pump, guided by frequent self-monitoring of blood glucose.

At the end of the study, blood glucose levels averaged seven percent in the intensively treated group and nine percent in the conventionally treated patients, who were then encouraged and shown how to adopt the intensive treatment. The DCCT findings prompted a major shift in the way doctors help patients manage type 1 diabetes.

As researchers followed participants over the next decade, they saw long-lasting effects of glucose control. The benefits of the first six years of intensive control persisted even though the average blood glucose level of the intensively treated group gradually rose to about eight percent, while the level of the conventionally treated group, which adopted the intensive treatment after the initial study, declined to eight percent during the same period.

In the follow-up study, among the 1,375 volunteers continuing participation, those whose initial six years of treatment were intensive had less than half the number of CVD events those whose initial six years of treatment were conventional (46 compared to 98 events). Such events included heart attacks, stroke, angina and coronary artery disease requiring angioplasty or coronary bypass surgery.

Thirty-one patients initially treated intensively (four percent) and 52 patients initially treated conventionally (seven percent) had at least one CVD event during the average 17 years of follow-up from the start of the DCCT. The average age of participants is now 45 years; 53 percent are male.

The latest findings, while focused on type 1 diabetes, raise the question whether glucose control is as important for people with type 2 diabetes. Growing evidence suggests that tight control benefits everyone with diabetes. However, strict control is hard to sustain and can lead to episodes of hypoglycemia, or low blood glucose.

Researchers expect an answer will come from the ACCORD trial (Action to Control Cardiovascular Risk in Diabetes), a major study testing ways to lower the risk of heart disease and stroke in adults with type 2 diabetes. Results of this NIH-funded study are due in 2009. The UI is participating in the ACCORD trial. In addition to Sivitz, UI researchers involved in that trial include Udaya Kabadi, M.D., UI Hospitals and Clinics endocrinologist and clinical professor of internal medicine, and Greg Doelle, M.D., UI Hospitals and Clinics endocrinologist and clinical associate professor of internal medicine.

For more information:

Roy J. and Lucille A. Carver College of Medicine

William Sivitz, M.D.

Greg Doelle, M.D.