ORLANDO – , according to final results from the VADT follow-up study (VADT-F).
Participants in the randomized, controlled VADT, which compared the effects of intensive versus standard glucose control in more than 1,700 patients with type 2 diabetes mellitus (T2DM), did not experience a significant improvement in the primary cardiovascular disease (CVD) outcome – a composite of myocardial infarction, stroke, cardiovascular death, new congestive heart failure, cardiovascular surgery or inoperable coronary artery disease, and ischemic amputation – after a median of 5.6 years of active treatment (hazard ratio, 0.88; P = .14). Nor did they experience significant improvement in secondary cardiovascular outcomes, including cardiovascular death and death from any cause (HRs, 1.32 and 1.07, respectively), or in a renal composite outcome (HR, 0.85), according to the findings published in 2009 (N Engl J Med. 2009 Jan 8;360[2]:129-39).
Dr. Peter Reaven
This was despite a rapid and statistically significant separation of hemoglobin A1c (HbA1c) levels between the treatment groups, Peter Reaven, MD, noted during a presentation of the final follow-up data at the annual scientific sessions of the American Diabetes Association.
Approximately 6 months after the start of the VADT, median HbA1c levels decreased from more than 9% in both groups to 6.9% and 8.4% in intensive and standard treatment groups, respectively (a median separation of 1.5%), said Dr. Reaven, director of the diabetes research program at the Phoenix VA Health Care System and a professor of clinical medicine at the University of Arizona in Phoenix.
“This was maintained throughout the study period,” he said. “All other risk factors during this period of time were equal between the two treatment groups.”
10-year outcomes
However, 10-year interim data from VADT-F, published in the New England Journal of Medicine (2015 Jun 4;372[23]:2197-206), showed a delayed benefit in these outcomes among those in the intensive control group: The incidence of the primary CVD composite outcome was reduced by 17% (HR, 0.83; P = .04) in favor of the intensive therapy at that time, Dr. Reaven said.
Dr. Nicholas Emanuele
The incidence of the renal composite outcome, which included estimated glomerular filtration rate less than 54 mL/min per 1.73m2, sustained macroalbuminuria, and end-stage renal disease, was reduced by 32% (HR, 0.68; P = .008), said Nicholas Emanuele, MD, who presented the VADT-F renal and microvascular outcomes at the ADA meeting.
At that 10-year follow-up, HbA1c levels in the intensive and standard treatment groups had nearly equalized (although they remained slightly better in the intensive treatment group), and eventually, the levels stabilized at about 8.2% in both groups through the end of the 15-year follow-up, the investigators said.
“So it was still lower by nearly 1.2 hemoglobin percent units, compared to baseline values nearly 15 years earlier, and despite ending the study in very good control, after we released these patients to the primary care providers for their diabetes care, there was a substantial rise in HbA1c levels over time ... illustrating the difficulty of controlling HbA1c values to this level in this advanced diabetes population,” Dr. Reaven said.