No mortality benefit after intensive glucose control once Hb A1c curves equalize

Background: A previous study reported that a median of 5.6 years of intensive versus standard glucose lowering in veterans with type 2 diabetes resulted in significantly reduced risk of major cardiovascular events after 10 years of combined intervention and observational follow-up.

Dr. Jessica Burke

Study design: Prospective cohort.

Setting: Veterans Affairs Healthcare System.

Synopsis: In the original trial, 1,791 veterans were randomly assigned to receive either intensive or standard glucose control therapy. After conclusion of that study, 1,655 participants were followed using central databases, and 1,391 also provided data via surveys and chart review. Initially the difference in the glycated hemoglobin (Hb A_1c) curves between the two groups averaged 1.5%, but it declined to 0.2%-0.3% 3 years after the trial ended. The median Hb A1c then stabilized to 8% in both groups.

Over a period of 15 years of combined intervention and posttrial follow-up, the risks of major cardiovascular events or death were not lower in the intensive-therapy group (hazard ratio for composite outcome, 0.91; 95% confidence interval, 0.78-1.06; P = .23; HR for death, 1.02; 95% CI, 0.88-1.18). The risk of major cardiovascular disease outcomes was reduced during the approximately 10-year interval of separation of the Hb A_1c curves (HR, 0.83; 95% CI, 0.70-0.99), but it did not persist after equalization of Hb A_1c levels (HR, 1.26; 95% CI, 0.90-1.75). Limitations include the observational study design, the study population of mostly older men, and reliance on administrative data for outcomes.

Bottom line: More than 5 years of intensive glucose lowering, compared with standard therapy, did not show significantly lower risks of cardiovascular events or mortality once the glycated hemoglobin curves equalized during follow-up in years 11-15.

Citation: Reaven PD et al. Intensive glucose control in patients with type 2 diabetes – 15-year follow-up. New Engl J Med. 2019 Jun 6;380(23):2215-24.

Dr. Burke is a hospitalist at Vanderbilt University Medical Center, Nashville, Tenn.