Intensive glycemic control reduces risk for major CV events, not mortality
Maintaining lower HbA1c levels may reduce overall cardiovascular events by up to 17%, but does not increase overall survival, according to research in The New England Journal of Medicine.
In an extended follow-up study of a randomized controlled trial of intensive vs. standard glucose control in U.S. military veterans with type 2 diabetes, researchers found that patients randomly assigned to intensive glucose control for an average of 5.6 years had 8.6 fewer major CV events per 1,000 person-years than those assigned to standard therapy.
“Our results, when combined with the results of the three other major clinical trials of glycemic control in type 2 diabetes, suggest that for every 1-point reduction in HbA1c, overall CV events are reduced by about 8% to 12%,” Rodney Hayward, MD, director of the Robert Wood Johnson Foundation Clinical Scholars Program at the University of Michigan and a senior research scientist with the VA Ann Arbor Healthcare System, told Endocrine Today. “However, we found no improvement in overall survival even after almost 12 years of follow-up.”
Hayward and colleagues analyzed data from 1,791 military veterans with type 2 diabetes (mean baseline age, 60.5 years; median diabetes duration, 11.5 years) participating in the Veterans Affairs Diabetes Trial (VADT). Participants were randomly assigned to intensive or standard glucose control for a mean of 5.6 years, ending in 2008. Researchers reviewed approximately 5 additional years of observational follow-up data from the cohort, relying on four national data registries.
After 9.8 years of follow-up, 288 major CV events occurred in the standard-therapy group vs. 253 CV events in the intensive-therapy group (HR = 0.83; 95% CI, 0.7-0.99). However, there were no significant between-group differences observed in CV mortality or all-cause mortality, according to researchers.
“In the absence of a reduction in total mortality and the small-to-moderate reduction in the rate of CV events, whether an individual patient should take additional medication to get their HbA1c below 8% will depend on many considerations, including patient life expectancy, risk of hypoglycemia, the amount of safety evidence for the medication being considered and patient preferences,” Hayward said. “Also, statin and blood pressure therapy remain the most important treatments for preventing heart attacks and stroke, since they have a risk reduction that is several times greater than the benefit observed with tight glycemic control, including substantial mortality reduction.”
Researchers plan to follow the study population to determine whether the CV benefits continue to increase over time, he said.
“There is some evidence that high blood sugar accelerates the natural aging of arteries, and if this is true, then the benefits we observed after 10 to 12 years may continue to increase over time,” Hayward said. “This would make tighter control even more important in younger patients with type 2 diabetes.” – by Regina Schaffer
Disclosure: Hayward reports no relevant financial disclosures. Please see the full study for a list of all other authors’ relevant financial disclosures.