Microvascular angina (cardiological syndrome X) per se is not associated with hyperinsulinaemia or insulin resistance

Background. Microvascular angina has been found to be associated with insulin resistance. However, many factors known to affect insulin sensitivity were not excluded in patient selection. We aimed to evaluate whether microvascular angina is per se associated with insulin resistance. Materials and methods. We performed a Frequently Sampled Intravenous Glucose Tolerance Test (0.33 g kg-1 b.w.) in 10 normal weight and normotensive patients with microvascular angina, with normal glucose tolerance and normal plasma lipids. Ten healthy subjects, comparable for age, sex, body mass index, blood pressure and plasma lipids, were used as control group. Results. Fasting serum glucose (4.49 ± 0.2 SEM vs. 4.52 ± 0.13 mmol L-1, P = 0.9), insulin (39.46 ± 3.68 SEM vs. 47.12 ± 4.6 pmol L-1, P = 0.21) and C-peptide (0.56 ± 0.05 SEM vs. 0.53 ± 0.05 nmol L-1, P = 0.68) values, as well as estimated parameters of insulin secretion and hepatic insulin extraction were similar in the two groups. Insulin sensitivity values (median, range) were also similar in the patients and control subjects (5.76 (3.39-12.30) vs. 7.54 (3.68-13.89.10-4.min-1/(μU/mL), P = 0.97). Conclusion. Microvascular angina per se is not associated with hyperinsulinaemia or insulin resistance when other confounding factors are excluded in patient selection.