NIH's ACCORD study: Intensive glucose treatment may not slow diabetes-related damage

WASHINGTON An intensive glucose treatment may not delay diabetes-related damage in patients with Type 2 diabetes that also are at high risk for heart attack and stroke, according to a National Institutes of Health-funded trial.

The Action to Control Cardiovascular Risk in Diabetes trial stressed that over time, diabetes damages the small blood vessels of the eyes, nerves, kidneys and other organs, leading to pain and disability. Heart disease due to damaged large blood vessels is a major cause of death in people with Type 2 diabetes. The longer a person has diabetes, the greater the chances of serious complications, including vision loss and blindness, foot ulcers and amputations, kidney disease and failure, and heart disease and stroke.

The ACCORD clinical study compared the effect of intensive control of blood sugar, blood pressure and blood lipids with standard, less-intensive treatments on the risk of major cardiovascular events in more than 10,000 adults with established Type 2 diabetes that averaged 62 years of age and were obese. The study’s intensive glycemia arm was halted in February 2008 due to excess deaths in that group. At that time, participants in the intensively treated group were moved to standard glucose control.

In addition to having Type 2 diabetes for an average of 10 years, about one-third had pre-existing heart disease, and the remainder had at least two additional cardiovascular disease risk factors. They also had high blood sugar, as measured by the hemoglobin A1c test, which shows average blood sugar in the preceding two to three months. Half of participants had an A1c more than 8.1% — above the currently recommended target for good control. A1c values in people without diabetes are less than 6%.

In ACCORD, the A1c target for the intensively treated group was less than 6%, a level seen in adults without diabetes and significantly lower than the levels tested in earlier trials. The goal for standard control was an A1c of 7 to 7.9%, an average range achieved by individuals treated for Type 2 diabetes in the United States. Both groups were treated with Food and Drug Administration-approved diabetes medications, as prescribed by their study clinician.

Eye, nerve and kidney complications in the two groups were compared after 3.7 years, when intensive control was halted, and again at the study’s end after 5 years.When intensive glucose treatment was halted in the group receiving such treatment, half those participants had an A1c of 6.4% or lower, which rose to 7.2% at study end. In the standard treatment group, that A1c measure was 7.5%, rising to 7.6% by the end of the study.

The treatment groups did not differ in the rate of progression to kidney failure, major vision loss or advanced peripheral neuropathy, a common nerve problem in diabetes that usually begins as tingling or numbness in the feet. However, people in intensive control had less deterioration in a vision test, and 20% fewer cataract surgeries compared with those in standard control. They also had a 30% lower rate of protein leakage in the urine, a sign of kidney disease and increased risk of heart disease. Testing for vibratory sensation, an indicator of nerve health, showed no difference between the groups, but the intensively controlled group scored better on other nerve tests.

The findings appeared in the June 29 issue of The Lancet, which coincided with a presentation of the study results at the American Diabetes Association's 70th annual scientific sessions in Orlando, Fla.

“In these ACCORD participants with established Type 2 diabetes and additional risk factors for cardiovascular disease, intensive lowering of blood glucose reduced some markers of eye, nerve and kidney disease compared with standard glucose control, but the groups did not differ in the rate of progression to kidney failure, nerve disease and major vision loss,” said lead author Faramarz Ismail-Beigi of Case Western Reserve University in Cleveland.

"ACCORD provides important data on the risks and benefits of intensive glucose control in people with established Type 2 diabetes,” said Susan B. Shurin, acting director of the NIH's National Heart, Lung and Blood Institute. “Although increasing treatment to try to achieve near-normal blood sugar provides some benefit, clinicians and patients should note that this treatment strategy also potentially increases the risk of adverse effects in patients with additional risk factors for heart disease, such as those studied in ACCORD."