Objective: Diabetes mellitus (DM) is a common comorbidity amongst patients that undergo coronary artery bypass grafting (CABG) at Veterans Affairs (VA) hospitals. We analyzed the effects of diabetes mellitus (DM) on outcomes after CABG in this unique population using data from the randomized endovein graft prospective (REGROUP, CSP #588, NCT01850082) trial.

Methods: In the REGROUP trial, 1,150 patients from 16 VA cardiac surgery centers were randomly assigned to open (OVH) vs. endoscopic (EVH) saphenous vein harvest. Data on baseline patient characteristics were collected prospectively. The primary outcome was a composite of major adverse cardiac events (MACE), comprised of all-cause mortality, nonfatal myocardial infarction and repeat revascularization. Patients were stratified by the diagnosis of DM. Unadjusted and adjusted analyses were completed at one-year follow-up and a median follow-up time of 4.7 years.

Results: DM was present in 577/1149 (50.2%) of patients in REGROUP. On univariate analysis, patients in the DM group were more likely to be non-white (18.7% vs. 11.7%; p<0.001) have hypertension (96% vs. 84.3%; p<0.001) and hyperlipidemia (90.1% vs. 82.7%; p<0.001). A prior history of stroke was higher in the DM group (10.2% vs. 6.5%; p=0.021). On multivariable analysis, there were no differences in MACE in the DM group at both one year (8% vs. 8%; OR 0.99; p=0.976) or at a median follow-up of 4.7 years (24.4% vs. 21.0%; HR 1.250; p=0.090).

Conclusions: In REGROUP, the presence of DM was not associated with an increased rate of MACE over a median follow-up of 4.7 years. Nevertheless, the trend towards better survival in patients without DM is noteworthy. On-going follow-up will be beneficial for further elucidation.