A mean of 3.7 years of intensive glucose-lowering therapy reduced the risk of nonfatal myocardial infarction in patients with advanced type 2 diabetes and a high risk of cardiovascular disease, but increased the risk of death, according to 5-year outcomes from the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial.
Thus, a therapeutic approach that targets glycated hemoglobin levels below 6% cannot be recommend in this population, Dr. Hertzel C. Gerstein of McMaster University, Hamilton, Ont., and colleagues from the ACCORD Study Group reported in the March 3 issue of The New England Journal of Medicine.
ACCORD participants were 10,108 type 2 diabetes patients with cardiovascular disease who were randomly assigned to receive intensive glucose-lowering therapy to a target hemoglobin A1c below 6.0% or to standard therapy with a target HbA1c of 7.0%-7.9%. The intensive therapy was terminated after a mean of 3.5 years because of higher mortality in the intensive treatment group, and patients from that group began receiving standard therapy. All participants were followed until the planned end of the trial; the current findings reflect an additional 0.2 months of intensive therapy not previously reported, and up to 17 months of additional follow-up.
Prior to the transition, the incidence of the primary outcome (a composite of nonfatal MI, nonfatal stroke, or death from cardiovascular causes) was 2.0% per year in the intensive therapy group, and 2.2% per year in the standard therapy group (hazard ratio 0.90). The difference between the groups remained nonsignificant throughout the entire period of observation.
Although the intensive therapy did lower the rate of nonfatal MI (1.08% vs. 1.35%, HR 0.79), it was also associated with a nonsignificant increased rate of death from cardiovascular causes (0.71% vs. 0.55%, HR 1.27).
"These divergent effects were retained at the end of the study, with a rate of nonfatal myocardial infarction in the intensive-therapy groups that was lower than in the standard-therapy group (1.18 vs. 1.42; hazard ratio 0.82) ... and a rate of death from cardiovascular causes that was higher (0.74 vs. 0.57; hazard ratio 1.29)," they found (N. Engl. J. Med. 2011;364:818-28).
At the time of transition, the death rate from any cause was a significant 21% higher in the intensive therapy* group (1.42 vs. 1.16), and it remained higher – by 19% - at the end of the study (1.53 vs. 1.27).
The findings indicate that 3.7 years of intensive therapy to target normal HbA1c in a high-risk population does not result in a significantly lower number of major cardiovascular events after 5 years, compared with therapy that targets "levels that are more typically achieved in person in the United States and Canada (i.e., 7 to 7.9%)," and indeed, the intensive approach was associated with more deaths, they said.
Reasons for the higher mortality in the intensive therapy group prior to the transition to standard therapy are unclear, although findings from ACCORD and other studies rule out hypoglycemia and the degree of reduction in glycated hemoglobin levels as a cause, the investigators noted.
"Further analysis should explore possible explanations, such as the role of various drugs, drug combinations, or drug interactions; weight gain; the relatively short intervention period (3.7 years); and the observed interaction between the blood pressure and glycemia trials with respect to mortality," they said.
ACCORD was supported by the National Institutes of Health and the Centers for Disease Control and Prevention. Study medication, equipment, or supplies were provided by numerous pharmaceutical companies. Dr. Gerstein has received consulting fees, institutional grant support, and/or lecture fees from Sanofi-Aventis, GlaxoSmithKline, Novo Nordisk, and several other drug companies. Individual ACCORD Study Group members’ disclosures are available with the full text of the article at http://www.nejm.com.
* CORRECTION, 3/7/2011: An earlier version of this article misstated which group had a 21% higher death rate from any cause. The intensive therapy group had this death rate at the time of transition. This version has been corrected.