A new study has revealed that an intensive therapeutic strategy targeting blood sugar to near-normal levels does not reduce heart attack or stroke risk, but increases risk of death, compared to standard treatment.
The researchers from Action to Control Cardiovascular Risk in Diabetes (ACCORD) evaluated the effects of intensively targeting blood sugar control among adults with type 2 diabetes, high blood sugar levels, and pre-existing heart disease or at least two cardiovascular disease risk factors in addition to diabetes.
"Adults with type 2 diabetes are two to four times more likely than adults without diabetes to die from heart disease, so identifying the safest and most effective ways to help them lower their risk of heart disease, stroke, and death is critical," said NHLBI Director Elizabeth G. Nabel, M.D.
"For these individuals, intensively lowering blood sugar to near-normal levels appears to be too risky," she added.
ACCORD randomly assigned 10,251 participants between the ages 40 and 79 (average age 62) to standard or intensive blood sugar treatment goals.
Therapy in both groups included patient education and counseling, and treatment with any of the major classes of Food and Drug Administration-approved diabetes medications.
52 percent of participants in the intensive strategy group were on three oral medications plus insulin compared with 16 percent of participants in the standard strategy group.
Hemoglobin A1C levels, a standard measure of average blood sugar levels over the preceding two to three months, were used to monitor participants' blood sugar.
The standard strategy group with 5,123 participants aimed to lower blood sugar levels to an A1C of 7 to 7.9 percent, a target similar to what is achieved, on average, by individuals treated for type 2 diabetes.
The intensive strategy group with 5,128 participants had an A1C blood sugar target of less than 6 percent, similar to that found in adults without diabetes.
The participants had an A1C level of 7.5 percent or higher and at study enrolment, one-half of the participants had an A1C level over 8.1 percent.
The findings revealed that half of the participants in the standard strategy group achieved an A1C less than 7.5 percent, and half of the intensive strategy group achieved an A1C less than 6.4 percent.
On average, participants in both groups achieved these levels within the first year of the study.
However, after an average of 3.5 years, 257 people in the intensive strategy group died, compared to 203 participants in the standard strategy group.
This difference of 54 deaths resulted in a 22 percent increased death rate in the intensive group.
The causes of death were similar in each group, from cardiovascular conditions, such as heart attack, sudden cardiac death, stroke, or heart failure.
However, the intensive group had 41 more cardiovascular deaths than the standard group, resulting in a 35 percent higher cardiovascular death rate.
"Despite detailed analyses, we have been unable to identify the precise cause of the increased risk of death in the intensive blood sugar strategy group," said lead author Hertzel C. Gerstein, M.D., M.Sc.
"Our analyses to date suggest that no specific medication or combination of medications is responsible. We believe that some unidentified combination of factors tied to the overall medical strategy is likely at play," Gerstein added.
The study will appear online in the New England Journal of Medicine (NEJM) today and will be in the June 12 NEJM print edition.