Hyperinsulinaemia and microvascular angina ("syndrome X") Glucose and insulin responses to a glucose load in 11 patients with angina attributed to microvascular coronary dysfunction were compared with those in 11 healthy subjects matched for age, sex, and body mass. Stimulated hyperinsulinaemia was demonstrated in the microvascular angina group. The findings suggest a role for increased concentrations of insulin in coronary microvascular dysfunction. 