Participants in the DCCT were tested to assess the develpment of diabetic kidney disease (nephropathy). Findings showed that intensive treatment prevented the development and slowed the progression of diabetic kidney disease by 50 percent.

Diabetic kidney disease is the most common cause of kidney failure in the United States and the greatest threat to life in adults with IDDM. After having diabetes for 15 years, one-third of people with IDDM develop kidney disease. Diabetes damages the small blood vessels in the kidneys, impairing their ability to filter impurities from blood for excretion in the urine. Persons with kidney damage must have a kidney transplant or rely on dialysis to cleanse their blood.
How Did Intensive Treatment Affect Diabetic Nerve Disease?

Participants in the DCCT were examined to detect the development of nerve damage (diabetic neuropathy). Study results showed the risk of nerve damage was reduced by 60 percent in persons on intensive treatment.

Diabetic nerve disease can cause pain and loss of feeling in the feet, legs, and fingertips. It can also affect the parts of the nervous system that control blood pressure, heart rate, digestion, and sexual function.

Neuropathy is a major contributing factor in foot and leg amputations among people with diabetes.
How Did Intensive Treatment Affect Diabetes-Related Cardiovascular Disease?

DCCT participants were not expected to have many heart-related problems because their average age was only 27 when the study began. Nevertheless, they underwent cardiograms, blood pressure tests, and laboratory tests of blood fat levels to look for signs of cardiovascular disease. The study proved that volunteers on intensive treatment had significantly lower risks of developing high cholesterol, a cause of heart disease. The risk was 35 percent lower in these volunteers, suggesting that intensive treatment can help prevent heart disease.

Elements of Intensive Management in the DCCT

• Testing blood sugar levels 4 or more times a day
• Four daily insulin injections or use of an insulin pump
• Adjustment of insulin doses according to food intake and exercise
• A diet and exercise plan
• Monthly visits to a health care team composed of a physician, nurse educator, dietitian, and behavioral therapist.

In the DCCT, the most significant side effect of intensive treatment was an increase in the risk for low blood sugar episodes sever enough to require assistance from another person. This is called severe hypoglycemia. Because of this risk, DCCT researchers do not recommend intensive therapy for children under age 13, people with heart disease or advance complications, older adults, and people with a history of frequent sever hypoglycemia. Persons in the intensive management group also gained a modest amount of weight, suggesting that intensive treatment may not be appropriate for people with diabetes who are overweight.

DCCT researchers estimate that intensive managment doubles the cost of managing diabetes because of incrased visits to health care professional and the need for more frequent blood testing at home. However, this cost is offset by the reduction in medical expenses related to long-term complications and by the improved quality of life of people with diabetes.

Results of the DCCT are reported in the New England Journal of Medicine, 329(14), September 30, 1993. Other articles related to the DCCT will be published in various journals during the next few years.

Prepared by the National Diabetes Information Clearinghouse.

NIH Publication No. 94-3874

August 1994