Endocrine Abstracts

Objective: Rimonabant has been shown to reduce weight, free androgen index (FAI) and insulin resistance in obese patients with PCOS compared to metformin. Metformin has also been shown to maintain the weight loss and enhance the metabolic and biochemical parameters achieved by treatment with rimonabant. We have determined the effect of rimonabant on the incretin hormones in patients with PCOS.

Design: A randomized open labelled parallel study of metformin and rimonabant for 12 weeks in 20 patients with PCOS with a body mass index (BMI) ≥30 kg/m² was undertaken. This was followed by an extension arm with the addition of metformin for another 12 weeks. All the patients who were on rimonabant were changed over to metformin for 3 months, whereas all the patients who were on metformin were continued on metformin for another 3 months.

Results: There was a significant increase in glucose-dependent insulinotropic polypeptide (GIP) levels after rimonabant treatment for 3 months (7.78±0.38 vs 21.62±1.96 pmol/l P value – 0.04) that returned to baseline when changed over to metformin (21.62±1.96 vs 8.94±0.4 pmol/l P value – 0.08). There were no significant changes in GIP levels either at 3 months or at 6 months with metformin. There were no significant changes in glucagon-like peptide-1 levels either after rimonabant or metformin treatment. There was no significant correlation between GIP and weight loss with rimonabant (r=0.12 P=0.89).

Conclusions: In these obese patients with PCOS, the beneficial effect of rimonabant might be partly due to an effect in GIP metabolism in addition to its endocannabinoid blocking effect.