Studies Differ on Benefits of Aggressive Blood Sugar Control
But experts say controlling glucose levels is key for most diabetics
FRIDAY, June 6, 2008 (HealthDay News) -- Two studies looking at the benefits of aggressively lowering blood sugar in people with type 2 diabetes have come to significantly different conclusions: One study found a 21 percent reduced risk for kidney disease, while the other found a 22 percent increased risk of death.
However, the first study found no increased risk of death by aggressively lowering blood sugar levels. And diabetes experts noted that the increased death risk found in the second study probably owed to the fact that the participants were "high-risk patients" -- more than one-third had suffered a heart attack or stroke before the trial began and the remainder had major cardiovascular risk factors. So the findings wouldn't apply to most people with type 2 diabetes, they note.
Both studies were presented Friday at the American Diabetes Association's annual meeting in San Francisco, and will be published in the June 12 issue of the New England Journal of Medicine.
The goal of both studies was to lower blood sugar levels through the aggressive use of drug therapy. In the second study, the goal was to reach an A1C level of less than 6 percent in the intensive therapy group, while the standard group goal was between 7 percent and 7.9 percent. When the U.S.-government sponsored trial was terminated 18 months early in February, the median A1C was 6.4 percent in the intensive group, compared to 7.5 percent in the standard group. A1C is a measure of blood glucose over the previous two to three months.
In the first study, called ADVANCE (Action in Diabetes and Vascular Disease), researchers found that among those who underwent intensive blood sugar control, there was a 21 percent reduced risk of developing kidney disease.
"Intensive glucose control significantly reduces serious vascular complications in diabetes, primarily kidney disease," lead researcher Dr. Anushka Patel, director of the Cardiovascular Division at the George Institute for International Health in Sydney, Australia, said during a teleconference Friday.
"There were no clear effects on macrovascular complications such as heart attack or stroke," Patel said. "Most importantly, using the strategy we employed for intensive glucose control, there was no increased risk of death."
In the study, 11,140 high-risk patients with type 2 diabetes either underwent intensive blood sugar control or standard treatment. By the end of the trial, most of the patients in the intensive care group were on several drugs, including insulin.
The ADVANCE researchers did not find any effect on cardiovascular disease between the two groups. The study also didn't find any increased risk of death for either group, unlike the second trial.
"These findings confirm what we already know -- that microvascular complications, and particularly kidney disease, is less with people whose blood sugar is intensively controlled," said Dr. Spyros Mezitis, an endocrinologist at Lenox Hill Hospital in New York City.
"This trial reassures us that we should be intensively controlling the blood sugar of patients so that we avoid microvascular complications," Mezitis added.
In the second study, called ACCORD (Action to Control Cardiovascular Risk in Diabetes), researchers found a 22 percent increased risk of death among patients receiving intensive blood sugar control, compared with those receiving standard treatment.
"In people with type 2 diabetes who are at high risk for cardiovascular disease, a therapeutic strategy that targets a blood sugar level below current recommendations increases mortality," ACCORD researcher Dr. Hertzel C. Gerstein, a professor in the Department of Medicine at McMaster University in Hamilton, Ontario, Canada, said during the teleconference.
"The reasons that people died was varied and there was no one reason that people died, and there was no clear difference in the actual cause of death in the intensive or standard group," Gerstein said. "Many analyses have been done to try to see if a reason could be found to explain why there was this mortality finding. At this point in time, none of these analyses have identified any one reason."
In the study, 10,251 patients with type 2 diabetes received intensive blood sugar control or standard treatment. During the trial, there was a 35 percent higher rate of death from cardiovascular events among patients in the intensive treatment group. However, those in the intensive care group also had a 24 percent lower risk of having a nonfatal heart attack. There was no difference between the groups in the risk for nonfatal stroke or heart failure, the researchers found.
Despite the findings of the ACCORD trial, one diabetes expert doesn't think they apply to most people with type 2 diabetes.
"Early and aggressive blood glucose control remains the optimum treatment approach for people with type 2 diabetes," said Dr. James A. Underberg, a clinical assistant professor of medicine at New York University Medical School.
Underberg said the results of the trial reflected the patient population in the study -- people with heart problems -- and not the dangers of aggressively lowering blood sugar.
"Data showing that high-risk patients are at greater risk for heart disease are not surprising, and should be considered a non-event for the average patient," Underberg said. "It's important that we don't lose sight of the benefits of lowering blood sugar, including fewer long-term microvascular complications."
"As I've always told my patients with type 2 diabetes, it's important to achieve and maintain your blood sugar goals," he said. "ACCORD hasn't changed any of that. The trial was conducted in a select patient population, which is just not reflective of the majority of the millions of Americans with type 2 diabetes."
To learn more about type 2 diabetes, visit the American Diabetes Association.