WEDNESDAY, March 2, 2011 (HealthDay News) -- Intensive blood sugar control doesn't benefit people with both type 2 diabetes and heart disease -- and it may harm them, researchers say.
Trying to maintain the blood sugar levels typical of people without diabetes can increase the risk of death for people with type 2 diabetes and heart disease by 19 percent, according to the latest analysis from the long-running ACCORD study.
"This study reports that at least over the five-year period of time, although there continued to be a reduction in the rate of [heart attack], a significant increase in mortality still exists," said the study's lead author, Dr. Hertzel C. Gerstein, the Population Research Health Institute Chair in Diabetes Research at McMaster University in Hamilton, Canada.
ACCORD stands for Action to Control Cardiovascular Risk in Diabetes. This study was designed to assess whether intensive blood sugar interventions to bring A1C levels to under 6 percent would benefit people with type 2 diabetes and heart disease. A1C is a long-term measure of blood sugar control, and the A1C level provides about two to three months of average blood sugar levels. A level of under 6 percent, which is considered normal or non-diabetic, can be difficult for someone with diabetes to achieve.
The people recruited for the ACCORD study were between 40 and 79 years old, and their A1C levels were above 7.5 percent at the start of the study. Study volunteers were randomly assigned to either intensive blood sugar control or to a standard diabetes program striving for levels of 7 percent to 7.9 percent.
The study began in 2001 and was halted in February 2008 when researchers realized that people in the intensive treatment group had an increased risk of dying. By then, the intensive treatment group had received 3.7 years of treatment aimed at lowering their A1C levels to below 6 percent. Achieving such tight blood sugar control often required numerous interventions, such as lifestyle changes along with medication, multiple medications or insulin therapy.
The analysis includes five years of data. For the intensive group, that meant an average of 3.7 years of intense treatment, followed by 1.3 years of standard therapy.
At the time the study was stopped, the intensive therapy group experienced a 21 percent reduction in the risk of heart attacks, but a 21 percent increase in the risk of all-cause mortality.
After five years, the researchers found that the risk of heart attacks was still decreased by 18 percent, but the increased risk of all-cause mortality also persisted. People in the intensive therapy group had a 19 percent increased risk of dying of any cause, according to the study, published March 3 in the New England Journal of Medicine.
Gerstein said many researchers have tried to tease out why intensive blood sugar control might up the risk of death, and so far, no one has succeeded. Causes that have been ruled out include 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. Even if we think something is the right thing to do, sometimes we may have findings that are unexpected," said Gerstein.
"This study confirms the results of the ACCORD trial over the full duration of the study," said Dr. Vivian Fonseca, president-elect of medicine and science for the American Diabetes Association.
"Overall, this means that the recommendations of the American Diabetes Association hold true. In general, people with diabetes should aim for an A1C goal of less than 7 percent, but clearly individualization is important. One size does not fit all," said Fonseca.
And, the findings suggest that people with type 2 diabetes and heart disease shouldn't attempt to achieve an A1C below 6 percent, the study authors said.
Gerstein and Fonseca noted that the ACCORD findings should not be generalized for 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.
"There is no reason to change current guidelines because of this study, and this study certainly doesn't support ignoring glucose control. We saw benefits in eye disease and many other outcomes with good control," said Gerstein.
To learn more about the connection between diabetes, heart disease and stroke, go to the U.S. National Institute of Diabetes and Digestive and Kidney Diseases.