|What Is the DCCT?
The DCCT is a clinical study conducted from 1983 to 1993 by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The study showed that keeping blood glucose levels as close to normal as possible slows the onset and progression of eye, kidney, and neuropathy caused by diabetes. In fact, it demonstrated that any sustained lowering of blood glucose helps, even if the person has a history of poor control.
The largest, most comprehensive diabetes study ever conducted, the DCCT involved 1,441 volunteers with type 1 diabetes and 29 medical centers in the United States and Canada. Volunteers had diabetes for at least 1 year but no longer than 15 years. They also were required to have no, or only early signs of, diabetic eye disease.
The study compared the effects of two treatment regimens--standard therapy
and intensive control--on the complications of diabetes. Volunteers were
randomly assigned to each treatment group.
What are the DCCT Study Findings?
Lowering blood glucose reduces risk:
The retina is the light-sensing tissue at the back of the eye. According
to the National Eye Institute, one of the National Institutes of Health,
as many as 24,000 persons with diabetes lose their sight each year. In
the United States, diabetic retinopathy is the leading cause of blindness
in adults under age 65.
How Did Intensive Treatment Affect Diabetic Kidney Disease?
Participants in the DCCT were tested to assess the development 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 type 1 diabetes. After having diabetes for 15 years, one-third of people with type 1 diabetes 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?
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
Elements of Intensive Management in the DCCT
In the DCCT, the most significant side effect of intensive treatment
was an increase in the risk for hypoglycemia (low blood sugar) episodes
severe enough to require assistance from another person. Because of this
risk, DCCT researchers do not recommend intensive therapy for children
under age 13, people with heart disease or advanced complications, older
adults, and people with a history of frequent severe 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 management
doubles the cost of managing diabetes because of increased visits to a
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.