June 4, 2003 -- Tight control of blood sugar fights off heart disease -- the No. 1 killer in both type 1 and type 2 diabetes -- a new study suggests.
Both findings appear in the June 5 issue of The New England Journal of Medicine. Both focus on people with type 1 diabetes. But the authors say that the findings probably hold true for people with type 2 diabetes, too. So does Suzanne Gebhart, MD, director of the diabetes unit at Emory Clinic and clinical section chief in endocrinology at Emory University in Atlanta. Gebhart was not involved in the studies.
"The main point is the important effect of blood-sugar control on complications of diabetes, whether these are heart or kidney complications," Gebhart tells WebMD. "I think that is the overreaching broad view of both articles."
What's Good for Type 1 ...
Type 1 diabetes usually starts when something makes the immune system destroy the cells that make insulin, the hormone that controls blood-sugar levels. Type 2 diabetes is a more complex disease. It begins when obesity or other factors make the body resistant to insulin. Because type 2 diabetes is a combination of complex factors, it's harder to study than type 1 diabetes. However, general findings in studies of type 1 diabetes often end up applying to type 2 diabetes as well.
Ten years ago, a revolutionary study -- the Diabetes Control and Complications Trial or DCCT -- showed that intensive blood-sugar control in type 1 diabetes is crucial. The better the blood-sugar control, the fewer eye, nerve, and kidney complications. But because these patients were fairly young and the duration of the study was short, it's been hard to show an effect on heart disease.
High Blood Sugar = Heart Disease
David M. Nathan, MD, director of the Massachusetts General Hospital Diabetes Center in Boston, leads a study following up on type 1 diabetes patients from the DCCT. They took ultrasound measurements of the carotid artery -- the huge blood vessel running from the heart to the brain -- in 1,229 of these patients. Six-and-a-half years later, they took new measurements.
Some of the news was bad. Even though these patients were only in their mid-30s, they had serious thickening of the arteries -- an early warning of heart disease and stroke. The good news: Those who kept their blood sugar under tight control had significantly less thickening of the arteries.
"Nothing about this new finding changes what we ask patients to do. But it reinforces our recommendations for intensive management of blood sugar," Nathan tells WebMD. "Patients with diabetes usually do succumb to heart disease. Now we know that with tight control of blood sugar, not only can we prevent other diseases, but we also have a good chance cutting the risk of heart disease."
Reversing Kidney Disease
Bruce A. Perkins, MD, MPH, noticed something funny about his type 1 diabetes patients at Harvard's Joslin Diabetes Center. Many of them had a sign of oncoming kidney disease called microalbuminuria -- increased protein in the urine. That's not unusual. But conventional wisdom says that this never goes away, although treatment can keep it from getting worse. Perkins' patients often did get better.
Perkins isn't the first doctor to notice this, so he designed a study to look at the issue. Over six years, he and colleagues studied 386 patients with microalbuminuria. They found that over the course of time, nearly 60% of patients improved.
The reason? They kept their blood sugar under control. In fact, type 1 diabetes patients were three times more likely to get over microalbuminuria if they controlled their blood sugar, lowered their cholesterol and blood-fat (triglyceride) levels, and lowered their blood pressure.
Warning: This only worked if the problem was caught in time. Once more serious kidney problems occur, the damage is done -- end-stage kidney disease is inevitable.
"This drives home the absolute importance of regular screening for microalbuminuria in people with type 1 diabetes," Perkins tells WebMD. "The chances for remission are present for only a short amount of time. Our theory is that the [protein] that leaks into the kidneys is toxic. So if you catch it earlier, it is easier to get rid of."
You Can Do It
How tight is tight? The better people with diabetes control their blood sugar, the better their health. But not everyone can achieve total control all of the time. The good news: Whatever improvement a person can make is good.
"People with diabetes need to find the best level of blood-sugar control that they can achieve," Nathan says. "They shouldn't despair if they can't do it all. The message is do the best that they can. What these data show is you don't necessarily have to achieve the lowest blood-sugar levels to get a benefit. Lower is better. But there is a spectrum of therapies that can be applied to keep blood sugar as close to normal as possible."