Tight blood-sugar control might harm some people with diabetes

Mar 4, 2011 4:45 PM

People with type 2 diabetes and heart disease who aim for too-aggressive control of their blood sugars increase their risk of death by 19 percent over 5 years, according to a study in the March 3 issue of the New England Journal of Medicine.

The on-going study looked at people with type 2 diabetes ages 40 to 79 whose A1C level, a measure of long-term blood-sugar control, was above 7.5 percent. Roughly half the people were assigned to an intensive-treatment group, with the aim of getting their A1C level below 6 percent, an effort that often requires major lifestyle changes and multiple drugs. Other people aimed for an A1C between 7 and 7.9 percent, a more practical goal.

The trial, which was originally designed to run five years, was stopped prematurely after an average of just 3.7 years, when researchers found that although the intensive-therapy group experienced a 21 percent reduction in heart attacks, they also experienced a 21 percent increase in all-cause mortality. After an additional 1.3 years, when the people in the intensive group had switched to the more-lax standard care, their incidence of heart attack was still decreased by 18 percent, but their all-cause mortality still increased by 19 percent.

Researchers still aren't sure why aggressive treatment increased the risk of death, but they don't think that low or fluctuating blood-sugar levels were responsible.

Bottom line: People with type 2 diabetes should still aim to get their A1C level down to between 6.5 and 7 percent, a level of control associated with a reduced risk of eye and kidney disease. But they shouldn't try to go much below 6.5 percent, especially if they have known heart disease.

--Joel Keehn, senior editor

See our tips on managing diabetes and our Ratings of blood-glucose monitors (for subscribers).