Effect of Baseline Glycemic Level on Long-Term Cardiovascular Outcomes After Coronary Revascularization Therapy in Patients With Type 2 Diabetes Mellitus Treated With Hypoglycemic Agents

The present study evaluated the association between preoperative hemoglobin A1c (HbA1c) levels and cardiovascular outcomes in patients with type 2 diabetes mellitus (DM) treated with hypoglycemic agents and undergoing coronary revascularization. We conducted a multicenter registry of Japanese patients undergoing first elective coronary revascularization. The present study included 3,571 patients whose HbA1c value at the index hospitalization was available. Of the 3,571 patients, 2,067 did not have DM and 1,504 had type 2 DM. Of the patients with type 2 DM, 202 had a HbA1c level of <6% (very low HbA1c group [VLG]), 426 had a HbA1c level of ≥6% but <7% (low HbA1c group), 405 had a HbA1c level of ʹ7% but <8% (intermediate HbA1c group), and 471 had a HbA1c level of ≥8% (high HbA1c group). The patients with type 2 DM treated with diet only were not included in the present study. The VLG had the lowest rate of freedom from major adverse cardiovascular events (MACE), a composite of cardiovascular death, myocardial infarction, and stroke. On multivariate analyses, the low HbA1c group had the lowest hazard ratio for MACE relative to those without DM (hazard ratio 1.13, 95% confidence interval 0.80 to 1.55). The VLG, intermediate HbA1c group, and high HbA1c group were significantly associated with an increased risk of MACE. On multivariate analyses of patients with DM using the low HbA1c group as a reference, a high HbA1c group level was significantly associated with an increased risk of MACE. The VLG and intermediate HbA1c group tended to be associated with an increased risk of MACE (VLG, hazard ratio 1.54, 95% confidence interval 0.98 to 2.40; intermediate HbA1c group, hazard ratio 1.44, 95% confidence interval 0.98 to 2.13). In conclusion, patients with type 2 DM treated with hypoglycemic agents and undergoing first elective coronary revascularization had significantly worse cardiovascular outcomes than patients without DM, except for patients with DM and a HbA1c of 6% to 7%. In the patients with DM, those with a HbA1c of 6% to 7% tended to have the lowest risk of MACE.