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June 6, 2008 -- Intense control of blood glucose levels in type 2 diabetes helps reduce the risk of kidney and eye complications, but not cardiovascular risks such as heart attacks and strokes, researchers said at a news briefing during the annual meeting of the American Diabetes Association in San Francisco.
In one of the two studies highlighted at the briefing, patients who reduced their hemoglobin A1c levels even lower than what is routinely recommended actually had a higher rate of death from cardiovascular problems. But the researchers point out that these were sicker patients than many with type 2 diabetes.
Hemoglobin A1c is a measure representing average blood glucose control for the previous three months. The American Diabetes Association recommends A1c levels of less than 7%. People without diabetes have an A1c of about 5%.
The bottom line for patients hoping to avoid all the diabetes-related complications? Lowering blood glucose levels does help reduce kidney and eye complications from diabetes, but paying attention to blood pressure and cholesterol levels is crucial to reduce the heart attack and stroke-related risks that accompany a diagnosis of type 2 diabetes, researchers from both studies say.
"You can safely reduce glucose A1c to about 6.5% by using the sort of gradual, gentle approach that we used," says Stephen MacMahon, PhD, an investigator of one study, called ADVANCE (Action in Diabetes and Vascular Disease). "It won't improve cardiovascular risks, but it will improve kidney risks."
"If you want to manage cardiovascular risks, focusing on blood pressure and lipids is likely where the money is," says John B. Buse, MD, PhD, president of medicine and science for the American Diabetes Association, who also participated in the briefing.
The studies, along with two editorials and a perspective, are published online in the New EnglandJournal of Medicine.
Both studies looked at the value of lowering blood glucose levels in those with type 2 diabetes more intensely that what is routinely recommended.
In the ADVANCE study, researcher Anushka Patel, MBBS, and colleagues followed more than 11,000 participants, assigning them to a standard group or to an intense control group with a goal of getting their A1c to 6.5%.
The average age of participants was 66, and about a third had already had a stroke or heart attack; the rest were at high risk for cardiovascular problems because of high cholesterol or other risk factors.
After five years, the intense group average A1c was 6.5% and the standard group, 7.3%, Patel says.
"The major effect shown in this is a 21% reduction in risk for kidney disease," Patel tells WebMD. "That was major."
While there was no significant reduction in heart attack, stroke, or death from cardiovascular disease with the intense group, they found "no evidence of increased risk of death [from cardiovascular disease] in the intensely controlled," Patel says.
"This is important because in the ACCORD study, they said those controlled at 6.5% had a significant increased risk of cardiovascular death and they don't know why," Patel says. That arm of the ACCORD study ended in February when the increased risk of death became apparent.