Selective effects of pioglitazone on insulin and androgen abnormalities in normo- and hyperinsulinaemic obese patients with polycystic ovary syndrome

BACKGROUND: To investigate the effectiveness and safety of pioglitazone (45 mg/day) on clinical and endocrine-metabolic features of polycystic ovary syndrome (PCOS), we studied 18 obese PCOS patients, classified as normoinsulinaemic (N-PCOS, n = 6) and hyperinsulinaemic (H-PCOS, n = 12) according to their insulin secretion. METHODS: Evaluation of clinical signs, hormonal and lipid profile assays, oral glucose tolerance tests and euglycaemic hyperinsulinaemic clamps were performed at baseline and after 2 (visit 2), 4 (visit 3) and 6 (visit 4) months of treatment. RESULTS: Body weight, body fat distribution and blood pressure remained stable throughout the treatment; hirsutism and acne significantly improved (P < 0.001 for visits 3 and 4 versus baseline) in both groups. A restoration of menstrual cyclicity was observed at visit 4 in 83% (P < 0.001) of H-PCOS and in 33% of N-PCOS. A decrease in LH, LH/FSH ratio, androstenedione and 17-hydroxy-progesterone was observed in both groups, attaining statistical significance in H-PCOS. A significant amelioration of insulin secretion, sensitivity and clearance was obtained in H-PCOS. A trend towards improvement was observed in lipid assessment of both groups. Therapy was well-tolerated. CONCLUSIONS: Present data suggest that there is a selective effect, partially independent of insulin secretion, of pioglitazone on the clinical and hormonal disturbances of PCOS.