Objective: To determine whether hyperinsulinism affects cytochrome P450c17 alpha activity by investigating the correlation between 17-hydroxyprogesterone (17-OHP) hyper-responsiveness to the gonadotropin-releasing hormone (GnRH) agonist, buserelin, and the insulin response to oral glucose in polycystic ovary syndrome (PCOS).
Design: Ultrasound, clinical and hormonal parameters were used to define PCOS in this prospective clinical study. We investigated the correlation between the 17-OHP response to buserelin testing and the insulin response to oral glucose in PCOS.
Methods: Twenty-eight women with PCOS and eighteen normal women were included in the study. 17-OHP response to buserelin, and insulin and C-peptide responses to oral glucose were measured.
Results: Twenty-five women with PCOS had an increased 17-OHP response. The PCOS patients showed significantly higher mean post-glucose load insulin and C-peptide levels than controls (P < 0.05). No significant correlations were found between basal 17-OHP and fasting insulin or fasting C-peptide, between peak 17-OHP and fasting insulin, peak insulin or peak C-peptide, between 17-OHP area under the curve (AUC) and insulin AUC or C-peptide AUC, and between percent increment in 17-OHP and insulin AUC or C-peptide AUC (P > 0.05).
Conclusions: Lack of a relationship between the 17-OHP response to the GnRH agonist buserelin and hyperinsulinism suggests that hyperinsulinism may not play a role in the dysregulation of the cytochrome P450c17 alpha enzyme seen in PCOS.