Context: Metformin treatment of women with polycystic ovary syndrome (PCOS) is widespread, as determined by studies with diverse patient populations. No comparative examination of weight changes or metabolite responses to different doses has been reported.
Objective: The aim of this study was to determine whether different doses of metformin (1500 or 2550 mg/d) would have different effects on body weight, circulating hormones, markers of inflammation, and lipid profiles.
Design: The study included prospective cohorts randomized to two doses of metformin.
Setting: The study was performed at a university teaching hospital with patients from gynecology/endocrinology clinics.
Patients: The patients studied were obese (body mass index, 30 to <37 kg/m2; n = 42) and morbidly obese (body mass index, > or =37 kg/m2; n = 41) women with PCOS.
Intervention: Patients were randomized to two doses of metformin, and parameters were assessed after 4 and 8 months.
Main outcome measures: The main outcome measures were changes in body mass, circulating hormones, markers of inflammation, and lipid profiles.
Results: Intention to treat analyses showed significant weight loss in both dose groups. Only the obese subgroup showed a dose relationship (1.5 and 3.6 kg in 1500- and 2550-mg groups, respectively; P = 0.04). The morbidly obese group showed similar reductions (3.9 and 3.8 kg) in both groups. Suppression of androstenedione was significant with both metformin doses, but there was no clear dose relationship. Generally, beneficial changes in lipid profiles were not related to dose.
Conclusion: Weight loss is a feature of protracted metformin therapy in obese women with PCOS, with greater weight reduction potentially achievable with higher doses. Additional studies are required to determine whether other aspects of the disorder may benefit from the higher dose of metformin.