Insulin Response to Oral Glucose Loading and Coronary Artery Disease in Nondiabetics

Abstract

Hyperinsulinemia is related to coronary artery disease (CAD), as an indication of decreased insulin sensitivity. Although there are many studies showing the relation between fasting insulin levels and insulin resistance, there are fewer studies on postprandial insulin levels. The aim of the present study was to investigate the relationship between postprandial insulin levels and CAD and its extent in our patients. For this purpose, oral glucose tolerance testing was performed in 222 patients with no known diabetes and who were scheduled to undergo diagnostic coronary angiography. The patients were first separated into two groups, one group (group I) having an insulin response within reference values to oral glucose loading, and the other group (group II) with a higher than normal insulin response. The presence and extent of CAD in the two groups were compared. While 65% of the patients in group 1 had CAD, this rate increased to 79% in group 2 patients (P = 0.02). The mean vessel scores were 0.92 ± 0.78 in group 1 and 1.67 ± 0.99 (P < 0.0001) in group 2 patients. The stenosis scores were 2.192 ± 2.077 in group 1 and 5.588 ± 3.519 (P < 0.001) in group 2, while the extent scores were 1.230 ± 1.292 in group 1 and 2.729 ± 1.847 in group 2 (P < 0.0001). The differences between the two groups were significant. Postprandial insulin values were positively correlated with CAD (P = 0.001, r = 0.214), vessel scores (P < 0.0001, r = 0.326), stenosis scores (P < 0.0001, r = 0.261), and extent scores (P < 0.0001, r = 0.419). Logistic regression analysis revealed hyperinsulinemia increased CAD independent from the other risk factors (OR = 5.742, CI 95%: 1.809-18.227, P = 0.003).