Is Tight Blood Sugar Control Risky?

Blood sugar control - that's the mantra of a person with diabetes. Keeping blood sugar under control helps prevent complications ranging from kidney failure to blindness. But for people with diabetes and heart disease, slightly less control may be better.

That's the latest conclusion from the long-running ACCORD study. (ACCORD stands for Action to Control Cardiovascular Risk in Diabetes.) Researchers found that people with type 2 diabetes who tried to reduce their blood sugar levels to those of a person without diabetes raised their risk of dying by 19 percent.

For the current study, researchers wanted to find out if taking aggressive action to control blood sugar levels would help people with both diabetes and heart disease. One important measure of blood sugar is the A1C test, which provides a two- to three-month average of blood sugar levels. The researchers wondered: Would dropping the A1C result to less than 6 percent - to the level of a person without diabetes - have benefits?

Two therapy groups

Volunteers ranged in age from 40 to 79 and had an A1C level of greater than 7.5 percent at the start of the study. Half the volunteers received intensive therapy, including lifestyle changes and medications aimed at lowering their A1C level. The other half received standard therapy that strove to keep the A1C level between 7 and 7.9 percent.

The study was halted when the researchers realized that volunteers in the intensive therapy group had an increased risk of dying. Although those in the intensive therapy group had reduced their heart attack risk by 21 percent, they had a 21 percent greater risk of dying in general. After five years, the risk was still elevated, at 19 percent.

Reasons are unclear

Hertzel C. Gerstein, M.D., at McMaster University in Ontario, Canada, says that many researchers have tried to tease out why intensive blood sugar control might boost the risk of death, and that so far, no one has succeeded. Researchers have ruled out as causes low blood sugar levels (hypoglycemia) and the rapid change in blood sugar levels.

"This study really reminds us that we always need to be prudent," says Dr. Gerstein. "Even if we think something is the right thing to do, sometimes we may have findings that are unexpected."

Dr. Gerstein emphasizes that the study findings shouldn't be applied to everyone with diabetes. People with type 1 diabetes and those with type 2 diabetes and no history of heart disease were not included in this study.

If you have diabetes, you should work with your health care provider to come up with an A1C goal appropriate for you. That generally means less than 7 percent.

Always talk with your health care provider to find out more information.