Strict glycemic control reduces EuroSCORE expected mortality in diabetic patients undergoing myocardial revascularization

Objective: We sought to evaluate the effect of a strict glycemic control protocol on a series of diabetic patients undergoing surgical myocardial revascularization. Methods: Between January 2003 and June 2004, 300 diabetic patients undergoing myocardial revascularization received a local protocol of insulin administration (protocol, group P). Patients were divided into 2 risk classes, according to their additive EuroSCORE value: low-moderate risk (0-4) and moderate-high risk (>4). The logistic EuroSCORE algorithm was used to calculate the expected probability of death. A control group was selected, including a series of 300 consecutive diabetic patients (no protocol group, group NP) who underwent coronary artery bypass grafting between March 2001 and September 2002, just before the introduction of the protocol. A propensity analysis was performed to control for selection bias. Results: Both groups showed similar EuroSCORE risk profiles: mean additive and logistic EuroSCORE values were 4.16 and 4.29 in group P versus 3.93 and 3.91 in group NP. Observed and expected mortalities of group P were 0.6% versus 1.8% (low-moderate risk), 2.5% versus 8.0% (moderate-high risk, P = .03), and 1.3% versus 4.3% (entire group, P = .01). Observed and expected mortalities of group NP were 1.6% versus 1.9% (low-moderate risk), 8.3% versus 7.5% (moderate-high risk), and 4.0% versus 3.9% (entire group). Logistic regression confirmed observed mortality in group P to be significantly lower than the expected logistic EuroSCORE mortality. After risk adjustment, the protocol allowed us to reduce the mortality odds by 72% (odds ratio, 0.282; 95% confidence interval, 0.092-0.859; P < .03). Subgroup analysis for moderate-to high-risk patients showed the protocol to improve mortality (odds ratio, 0.24; P < .05), whereas no significant improvement was found in low- to moderate-risk patients. Addition of the propensity score to the multivariable analysis did not significantly displace P values and odds ratios. Sensitivity analysis of patients who underwent coronary artery bypass grafting without additional procedures showed the protocol to maintain its protective effect (odds ratio, 0.15; P < .05). Conclusion: Optimal glucose control highly reduces EuroSCORE expected mortality in diabetic patients undergoing myocardial revascularization, especially in moderate-to high-risk patients.