Despite encouraging late outcomes, the use of bilateral internal thoracic artery (BITA) grafting for myocardial revascularization in diabetic patients remains controversial because of an increased risk of sternal complications. In the present study, early and long-term outcomes of the routine use of left-sided BITA grafting in insulin-dependent diabetic patients were reviewed retrospectively. Among the 2701 consecutive patients who underwent isolated BITA grafting at the authors' institution from 1999 throughout 2012, 188 (mean age: 67 ± 9 years) were insulin-dependent diabetic patients. The mean expected operative risk, calculated according to the European System for Cardiac Operative Risk Evaluation II, was 11 ± 10.8%. There were 6 (3.2%) hospital deaths. Prolonged invasive ventilation (17.6%), multiple transfusion (16.5%), deep sternal wound infection (DSWI, 11.7%) and acute kidney injury (10.6%) were the most frequent major postoperative complications. Chronic lung disease (P = 0.08), low cardiac output (P = 0.039), multiple transfusion (P = 0.034) and mediastinal re-exploration (P = 0.071) were risk factors for DSWI. The mean follow-up was 5.7 ± 3.6 years. The 10-year non-parametric estimates of overall survival, freedom from cardiac and cerebrovascular death, and major adverse cardiac and cerebrovascular events were 57.7 [95% confidence interval (CI): 45.1-66.2], 83.6 (95% CI: 76.6-90.7) and 55.4% (95% CI: 44.7-66.1), respectively. Predictors of decreased late survival were old age (P = 0.013), chronic lung disease (P = 0.004), renal impairment (P = 0.009) and left ventricular dysfunction (P = 0.035). Left-sided BITA grafting may be performed routinely even in insulin-dependent diabetic patients. The increased rates of postoperative complications do not prevent low early mortality and good long-term outcomes. © The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.