Increased secretion of insulin during oral glucose tolerance test can be a predictor of stent restenosis in nondiabetic patients

Abstract

Insulin is known to stimulate proliferation and migration of vascular smooth muscle cells. As the predominant mechanism of restenosis after stent implantation is neointimal tissue proliferation, one can expect a relationship between hyperinsulinemia and restenosis in these patients. The aim of this study was to determine whether hyperinsulinemia during oral glucose tolerance test is a predictor of the development of restenosis after stent implantation in nondiabetic patients. We prospectively studied 52 nondiabetic patients with effort angina who underwent elective stent implantation for single-vessel coronary artery disease. In order to increase the statistical power of the study, numerous exclusion criteria were applied. All patients were subjected to a 75 g oral glucose tolerance test a day before the stent implantation and underwent follow-up angiography 6 months later. Plasma insulin levels in fasting (6.77 +/- 1.57 vs. 5.36 +/- 1.35 muU/ml; P = 0.005), at 30 min (102.48 +/- 10.6 vs. 47.74 +/- 12.75 muU/ml; P = 0.001), 1 hr after (120.23 +/- 14.1 vs. 63.08 +/- 12.62 mu/ml; P = 0.001), 2 hr after (63.58 +/- 8.64 vs. 34.88 +/- 6.82 mu/ml; P = 0.001), and 3 hr after (25.71 +/- 5.65 vs. 23.02 +/- 4.61 mu/ml; P = 0.04) loading were significantly higher in patients with stent restenosis than in patients without stent restenosis. Insulin area and insulin area/glucose area were also significantly higher in patients with stent restenosis than in patients without (219.5 +/- 23.8 vs. 118.9 +/- 21.8, P = 0.001, and 0.62 +/- 0.09 vs. 0.33 +/- 0.06, P = 0.001, respectively). By multiple logistic regression analysis, insulin area during oral glucose tolerance test was found to be an independent predictor of stent restenosis (OR = 1.12; 95% CI = 1.01-1.25; P = 0.031). In conclusion, nondiabetic patients with hyperinsulinemia during oral glucose tolerance test have a high risk for restenosis after stent implantation, and performing this simple test before intervention may be useful for the prediction of stent restenosis.