Abnormal response of insulin to glucose loading and assessment of insulin resistance in non-obese patients with polycystic ovary syndrome

Objectives. To investigate the insulin response to glucose loading and to determine which method is best in order to evaluate insulin resistance in women with polycystic ovary syndrome (PCOS). Methods. In order to eliminate the influence of obesity on the variables, all subjects were non-obese. Standard oral glucose tolerance tests were performed in 23 normal women and 21 patients with PCOS. Insulin resistance was evaluated by the homeostasis model assessment insulin resistance index (HOMA-IR), homeostasis model assessment for beta-cell function (HOMA-%B), the quantitative insulin-sensitivity check index (QUICKI) and area under the curve for glucose (AUC(glucose)) and insulin (AUC(insulin)). Results. The mean values of HOMA-IR, AUC(insulin) and AUC(glucose) in the PCOS group were significantly higher than in the BMI-matched normal control group (p < 0.05, p < 0.01 and p < 0.01, respectively). There were significant positive correlations between AUCinsulin and AUCglucose and androgens or luteinizing hormone in all subjects (p < 0.001). However, HOMA-IR and fasting insulin were significantly correlated only with total testosterone (p < 0.05). AUC(insulin) and AUC(glucose) values were elevated in more than 50% of PCOS patients with normal values of HOMA indices. Conclusion. In the PCOS group, the abnormal response of insulin to glucose loading was suggested. AUC(insulin) may be a better index than others to evaluate insulin resistance in non-obese PCOS patients.