WASHINGTON -- Diabetics who tightly control their blood sugar levels can cut their risk of heart attacks and strokes in half, a study shows.
The findings, from nearly 1,400 diabetics who have been followed for more than a decade, provide the first direct evidence that the risk of the most serious complication of the disease, which affects millions of Americans, can be minimized by aggressive treatment, specialists said.
''This is the most important diabetes news of the year," said David Nathan of Harvard Medical School, who co-chaired the study being published in today's issue of the New England Journal of Medicine. ''This is the remaining piece of the puzzle with regard to our ability to take the teeth out of diabetes and make it a less dangerous disease."
Nearly 21 million Americans have diabetes, and the number is rising because of the increasing number of elderly and obese people.
Diabetics' bodies are unable to control the amount of sugar in their blood. Over time, elevated sugar levels can cause damage throughout the body, making diabetics prone to a variety of health problems that include blindness, kidney failure, nerve damage that sometimes requires amputations, and, most seriously, heart attacks and strokes.
In 1993, Nathan and his colleagues revolutionized the treatment of the disease when they reported the landmark Diabetes Control and Complications Trial, in which 1,441 patients with Type 1 diabetes were put on a strict regimen aimed at tightly controlling their blood sugar and followed beginning in 1983.
When the study began, the practice of most diabetics was to test their blood sugar once a day and give themselves one or two insulin injections daily. The strict regimen used in the study involved multiple blood sugar tests every day and a minimum of three insulin injections or the use of an insulin pump.
The results, hailed as the most important development in diabetes since insulin, showed that after about six years the strict regimen sharply reduced the risk of the most common complications -- eye, kidney and nerve damage. As a result, most doctors began to advocate the aggressive treatment approach and many patients adopted the much more intense, difficult lifestyle.
But that study was too short to determine whether strict blood sugar control would also reduce the risk of heart disease, which kills 75 percent of diabetics and is the leading cause of death among them. For the new study, researchers continued to follow 1,394 subjects from the original study until Feb. 1 of this year, to determine the impact on heart disease and stroke.
The diabetics on the strict regimen were 42 percent less likely to experience any kind of heart problem and 57 percent less likely to suffer the most serious problems, such as heart attacks or strokes, the researchers found.
''That's a pretty dramatic reduction," Nathan said. ''Short of curing diabetes this is one of the final answers in the puzzle as to whether we can decrease the complications from the disease."
The findings should push more doctors to encourage their patients to embrace the aggressive approach, and more diabetics to work harder at controlling their blood sugar levels, specialists said.
''It requires eternal vigilance and it's hard. But this is pretty definitive evidence of the value of making that effort," said Judith Fradkin of the National Institute of Diabetes and Digestive and Kidney Disorders, which funded the study.
About 5 percent to 10 percent of diabetics suffer from the Type 1 form of the disease, which usually begins in childhood and is caused by a breakdown in the body's ability to make insulin. Evidence suggests patients with the more common Type 2 diabetes, in which the body either cannot produce enough insulin or cannot use it adequately, are likely to experience similar benefits, specialists said.