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 author
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