Endothelial dysfunction of coronary arteries in subjects without diabetes: An association with both insulin resistance and impaired insulin secretion response

•Coronary ED is associated with insulin resistance.•Coronary ED is also associated with impairments in insulin secretory response.•Decreases in LDL particle size, not the total LDL-Ch, influences coronary ED.•Coronary ED is also influenced by impaired fibrinolysis. This study was aimed to compare insulin sensitivity and secretion response, lipoprotein and plasminogen activator inhibitor 1 (PAI-1) levels between the subjects with and without coronary artery endothelial dysfunction (ED). ED was detected by intracoronary injection of acetylcholine (ACh) in 47 nondiabetes subjects without stenotic coronary arteries, selected from 316 consecutive patients with coronary angiography performed for suspected coronary artery disease. The subjects were divided into two groups: presence of ACh-induced coronary spasm (group ED+, N = 30) and absence of ACh-induced coronary spasm (group ED−, N = 17). Insulin sensitivity (Si) was evaluated by frequently sampled intravenous glucose tolerance test (FSIGTT) with minimal model analysis and by HOMA-IR, insulin secretion by acute insulin response (AIR) (calculated from the first 8 min of FSIGTT) and by disposition index (DI) (Si × AIR). Lipids and PAI-1 levels were determined enzymatically, and LDL particle size by gradient gel electrophoresis. Si was significantly lower (4.22 ± 0.62 vs 6.98 ± 1.47 min−1/mU/l × 104; p