The effect of combination therapy with metformin and combined oral contraceptives (COC) versus COC alone on insulin sensitivity, hyperandrogenaemia, SHBG and lipids in PCOS patients

BACKGROUND: Neither oral contraceptives (COC) nor metformin are an optimal modality for the long-term treatment of polycystic ovary syndrome (PCOS). The aim of this study was to evaluate whether a combination of both is beneficial over COC monotherapy. METHODS: Altogether, 30 women were included in the study and 28 finished the protocol. The patients were randomly assigned to two groups treated with either COC (COC group) or COC and metformin (1500mg/day) (METOC group) for 6 months. Anthropometric parameters, androgens, lipids, fasting insulin, glucose and sex hormone binding globulin (SHBG) concentrations were measured before and at the end of the sixth cycle of treatment. The insulin sensitivity index was evaluated using the euglycaemic clamp. RESULTS: There were no significant changes in anthropometric parameters, fasting glucose or insulin sensitivity in either group. Total testosterone, free androgen index, androstenedione and dehydroepiandrosterone decreased and SHBG increased significantly in both groups. When comparing the effect of both treatments, only a more pronounced decrease in free androgen index was found in the METOC group. CONCLUSIONS: Adding metformin slightly modified the treatment effect of COC, causing a more significant decrease in the free androgen index but having no additional positive impact on lipids, insulin sensitivity, SHBG or testosterone. The available data do not offer enough evidence to advocate the standard use of combined treatment in PCOS. Whether the combination might be beneficial for specific subgroups of patients is of further interest.