Abstract 416: Baseline Electrocardiographic Findings Are Associated With Insulin Sensitivity and Beta-Cell Function in Type 2 Diabetes

Abstract

Introduction Cardiovascular disease rates are higher in type II diabetes mellitus, but often it remains silent until too late. It is unknown if baseline EKG changes are associated with the degree of impaired insulin sensitivity or with other markers of diabetes control. We sought to investigate these relationships in the Penn Diabetes Heart Study (PDHS), a cross-sectional study of diabetic patients without overt coronary artery disease. Methods EKG intervals were measured in a subset of PDHS participants (n=732; mean age 59.4 ± 8.4 years, 66.5% males, 60.1% Caucasians). At the same visit, subjects underwent 75 g oral glucose tolerance testing after overnight fast with measurement of glucose and insulin at 0, 30, 60, and 120 minutes. The Matsuda Insulin Sensitivity Index (MISI) was calculated to estimate insulin sensitivity and the Insulinogenic Index (IGI) to estimate pancreatic beta-cell function. We used spearman correlations, chi-squared tests, and logistic regression to test associations of EKG changes with clinical factors, log-transformed MISI, and inverse normal-transformed IGI. Results In unadjusted analysis, there was a higher prevalence of left ventricular hypertrophy (LVH) (3.6% vs. 0.9%, p = 0.005) and ST changes (24.5% vs. 14.6%, p = 0.004) in African Americans compared to Caucasians. In fully adjusted models controlling for age, race, sex, history of hypertension and Framingham risk score, a higher MISI was associated with lower incidence of Q waves (OR 0.50, CI 0.33-0.76, p = 0.001). In addition, higher IGI scores were associated with a lower incidence of nonspecific ST changes (OR 0.82, CI 0.65-0.96, p= 0.035). There was also a trend for higher HbA1c values associated with LVH; however, this association was not statistically significant in fully adjusted models (OR 1.29, CI 0.90-1.86, p = 0.163). Conclusion Q wave abnormalities on routine EKGs were associated with reduced insulin sensitivity at baseline, while nonspecific ST changes were associated with lower pancreatic beta-cell function in patients with diabetes. Specific baseline EKG changes are indicators of the degree of metabolic disturbance in type 2 diabetes and may provide insight into the extent and risk of macrovascular and microvascular complications in diabetic patients.