The long-term effects of tightly controlling hemoglobin A1c (HbA1c) levels has been found to reduce the risk for myocardial infarction, stroke, heart failure, or amputation by approximately 17%, according to a study published online June 4 in the New England Journal of Medicine. 

Lead author Rodney Hayward, MD, and colleagues concluded that a long-term average HbA1c of approximately 8% was sufficient to be beneficial, but many patients can be safely lowered to approximately 7%. Their study conducted an extended follow-up of 1,791 military veterans enrolled in the Veterans Affairs Diabetes Trial (VADT). 

The VADT, which had a median follow-up of 5.6 years, found that intensive lowering of blood glucose did not significantly reduce the rate of major cardiovascular events, when compared with standard therapy. However, over a median follow-up of 9.8 years, Dr. Hayward and colleagues found that the intensive-therapy group had a significantly lower risk of heart attack, stroke, new or worsening congestive heart failure, amputation for ischemic gangrene, or cardiovascular-related death, when compared with the group receiving standard therapy. 

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They found an absolute reduction in risk of 8.6 major cardiovascular events per 1,000 person-years but no reduction in cardiovascular mortality or total mortality. 

“Taken together with findings from other large studies, we see that controlling blood sugar in diabetes can indeed decrease cardiovascular risk, though we continue to see no effect on risk of dying during the same time period,” Dr. Hayward said. “This finding reinforces the importance of combining good blood sugar control with control of other cardiovascular risk factors for a combined effect. 

“Once someone has his or her A1c around 8%, we need to individualize treatment to the patient, balancing his or her individual cardiovascular risk based on personal and family history, his or her age and life expectancy, smoking history , and medication side effects,” Dr. Hayward commented.