BACKGROUND:

It has been reported that women with polycystic ovary syndrome (PCOS) benefit from metformin therapy.

METHODS:

A randomized, placebo-controlled, double-blind study of obese (body mass index >30 kg/m2), oligo-/amenorrhoeic women with PCOS. Metformin (850 mg) twice daily was compared with placebo over 6 months. All received the same advice from a dietitian. The primary outcome measures were: (i) change in menstrual cycle; (ii) change in arthropometric measurements; and (iii) changes in the endocrine parameters, insulin sensitivity and lipid profile.

RESULTS:

A total of 143 subjects was randomized [metformin (MET) = 69; placebo (PL) = 74]. Both groups showed significant improvements in menstrual frequency [median increase (MET = 1, P < 0.001; PL = 1, P < 0.001)] and weight loss [mean (kg) (MET = 2.84; P < 0.001 and PL = 1.46; P = 0.011)]. However, there were no significant differences between the groups. Logistic regression analysis was used to analyse the independent variables (metformin, percentage of weight loss, initial BMI and age) in order to predict the improvement of menses. Only the percentage weight loss correlated with an improvement in menses (regression coefficient = 0.199, P = 0.047, odds ratio = 1.126, 95% CI 1.001, 1.266). There were no significant changes in insulin sensitivity or lipid profiles in either of the groups. Those who received metformin achieved a significant reduction in waist circumference and free androgen index.

CONCLUSIONS:

Metformin does not improve weight loss or menstrual frequency in obese patients with PCOS. Weight loss alone through lifestyle changes improves menstrual frequency.