Cardiovascular disease is the leading cause of diabetes-related deaths. In patients with type 2 diabetes mellitus (T2DM) approximately 68% die from heart disease and 16% from stroke, a rate approximately 2 to 4 times higher than in adults without diabetes.1 Although T2DM is an independent risk factor for CVD, the increased risk is multifactorial due to the high rate of concomitant risk factors including hypertension, dyslipidemia, and obesity.
The results of the Bypass Angioplasty Revascularization Investigation 2 Diabetes (BARI 2D) were recently published.2 Over 2300 patients with a diagnosis of both T2DM and coronary artery disease (CAD) who were candidates for elective percutaneous coronary intervention (PCI) or coronary-artery bypass grafting (CABG) were enrolled. Patients were excluded from the trial if immediate revascularization was required or if patients had left main coronary disease, a serum creatinine >2 mg/dL, a glycated hemoglobin (HgbA1c) >13%, class III or IV heart failure, hepatic dysfunction, or had underwent PCI or CABG within the previous 12 months. Patients were randomly assigned to two treatment strategies in a 2-by-2 factorial design. The first strategy assigned patients to undergo either prompt PCI (within 4 weeks after randomization) or medical therapy. The second strategy assigned patients to undergo either insulin-sensitization therapy or insulin-provision therapy to achieve an HgbA1c <7%. If an HgbA1c of < 8% could not be maintained, patients in the insulin-sensitization group could receive insulin-providing drugs and patients in the insulin-provision group could receive insulin-sensitizing drugs. All patients were treated according to guideline goals; HgbA1c <7%, low density lipoprotein (LDL) cholesterol <100 mg/dL, and a blood pressure of <130/80 mmHg. A unique aspect of the trial design was that randomization was stratified according to the method of revascularization (PCI or CABG), determined a priori by the responsible physicians as deemed appropriate for each patient. The primary endpoint was death from any cause and the secondary endpoint was a composite of death, myocardial infarction, or stroke (major cardiovascular events).
Approximately 4600 patients with T2DM consented to screening; however, nearly 2200 of these patients were ineligible for randomization and 68 decided not to participate. This left a remaining 2368 patients to be randomized. Almost 93% of patients completed the trial with an average follow up of 5.3 years. Of the 2368 patients enrolled, 763 patients were selected for CABG (385 randomized to medical therapy and 378 to revascularization) and 1605 patients were selected for PCI (807 were randomized to medical therapy and 798 were randomized to revascularization). Patients were then randomly assigned to a insulin provision or a insulin sensitization group within each of these strata. Baseline characteristics were similar between the groups. At baseline, about 80% of the patients had symptomatic myocardial ischemia and had diabetes an average of 10.4 years.
There was no significant difference regarding the rates of death from any cause between the revascularization group and the medical therapy group in either the CABG or PCI groups. In the CABG group, there were statistically significant fewer major cardiovascular events in the revascularization group than in the medical therapy group; however, in the PCI group there was no difference in the rates of cardiovascular events between the patients in the revascularization group and medical therapy group. There was a significant benefit with prompt coronary revascularization compared with medical therapy in patients in the CABG group versus the PCI group. Fewer nonfatal myocardial infarctions occurred in the revascularization group (7.4%) than in the medical therapy group (14.6%) in the CABG group.