THE ROLE OF INSULIN IN OVARIAN SIZE IN PATIENTS WITH THE POLYCYSTIC-OVARY-SYNDROME

The objective of this study was to evaluate whether the degree of supp ression of ovarian volume effected by a gonadotropin releasing hormone (GnRH) agonist in patients with polycystic ovary syndrome (PCOS) corr elated with basal insulin secretion and insulin secretion provoked by a glucose challenge. Eighteen PCOS patients received the GnRH agonist D-tryptophan-6-LHRH (Decapeptyl, 3.75 mg monthly i.m.) for 6 months an d had blood glucose and insulin measured during a 75 g oral glucose to lerance test (OGTT) prior to and at the end of therapy. According to o varian volume suppression after GnRH agonist therapy, two groups were defined: in group A (n = 10; mean body mass index (BMI) +/- SEM, 25.6 +/- 1.6 kg/m2) ovarian volume regressed from 17.9 +/- 1.6 to 6.7 +/- 0 .3 ml (full responders) and in group B (n = 8; mean BMI +/- SEM, 28.1 +/- 2.3 kg/m2) from 21.5 +/- 1.1 to 15.1 +/- 1.0 ml (partial responder s). Results showed that GnRH agonist therapy did not affect significan tly BMI or fasting levels and area under the curve (AUC) for glucose a nd insulin in the respective groups. Fasting insulin levels correlated positively with ovarian volume prior to (r = 0.56, p < 0.05) and afte r 6 months of GnRH agonist therapy (r = 0.80, p < 0.005). The suppress ibility of ovarian volume with GnRH agonist therapy correlated negativ ely with the difference between maximal and basal levels (r = -0.68), the area under the curve (r = -0.62) and maximal levels (r = -0.72) fo r insulin during the OGTT. This study shows that insulin output per se seems to be an important determinant of ovarian volume in women with PCOS. Furthermore, it would appear that GnRH analogues are less effect ive in reducing ovarian volume in patients with excessive insulin secr etion.