The effects of insulin therapy on mortality in diabetic patients undergoing percutaneous coronary intervention

Background: A growing number of studies have reported insulin therapy to be associated with a higher incidence of major adverse cardiac events in diabetic patients with coronary artery disease. However, the relationship between insulin use and the clinical outcomes of patients with diabetes who undergoing percutaneous coronary intervention (PCI) has not been fully clarified. Methods: A total of 1,069 consecutive patients with diabetes who underwent PCI were enrolled and divided into 2groups: oral hypoglycemic agents (OHA) group (709 patients) and insulin therapy group (360 patients). The primary and secondary endpoints of this study were all-cause death and cardiac death, respectively. Results: At baseline, the maximum creatine kinase-MB (CK-MB), plasma glucose, hemoglobin A1c, high-sensitivity C-reactive protein (CRP), and creatinine levels were higher, while the left ventricular ejection fraction (LVEF) was lower, in the insulin therapy group than in the OHA group. After propensity score matching of baseline characteristics, for patients treated with insulin, the odds ratios of death from any cause in hospital, within 1 year of surgery, and within 2 years of surgery were 12.03 (95% CI: 1.486-97.33, P=0.020), 10.33 (95% CI: 1.21-88.12, P=0.033), and 2.99 (95% CI: 1.22-7.31, P=0.016), respectively, and the odds ratios of cardiac death were 10.33 (95% CI: 1.21-88.12, P=0.033), 6.49 (95% CI: 1.33-31.59, P=0.021), and 5.27 (95% CI: 1.45-19.13, P=0.011), respectively. Generalized estimating equations analysis showed the odds ratios of all-cause death and cardiac death for insulin-treated patients to be 4.77 (95% CI: 1.76-12.95, P=0.002) and 5.38 (95% CI: 1.29-22.96, P=0.023), respectively. Conclusions: Compared with OHA, insulin therapy significantly increases the risk of in-hospital all-cause and cardiac death in patients with diabetes undergoing PCI, and the risk remains significantly at least 2 years after surgery.