The effect of metformin and myoinositol on metabolic outcomes in women with polycystic ovary syndrome: role of body mass and adiponectin in a randomized controlled trial

PURPOSE To compare the effects of insulin sensitizers metformin (MET) and myo-inositol (MI) on adiponectin levels and metabolic characteristics in women with polycystic ovary syndrome (PCOS) with respect to their body mass index (BMI). METHODS In this open label, parallel randomized clinical trial, 66 women with PCOS (33 normal-weight and 33 overweight/obese) were randomized to either MI (4 g/day) or MET (1500 mg/day) for a period of 6 months. Serum concentration of adiponectin, hormonal and metabolic laboratory outcomes and clinical assessment of BMI, body composition and Ferriman-Gallwey score (FG score) were evaluated before and after treatment. RESULTS After the 6-month intervention, comparison between MET and MI in time to treatment analysis showed no significant differences between the two treatments for all analyzed parameters. Only borderline significantly lower AUC glucose was found in the MET group in comparison to the MI group (p = 0.071). The main effect of treatment was shown for glucose concentration at 120 min OGTT (p = 0.032) and testosterone (p = 0.002). The main effect of time was shown for body mass (p = 0.004), waist circumference (p < 0.001), BMI (p = 0.003), body fat mass (p = 0.001), adiponectin (p = 0.020), fasting glucose (p = 0.001), testosterone (p = 0.015), SHBG (p = 0.013), 17OH progesterone (p = 0.008), LH (p = 0.004) and estradiol (p = 0.014). CONCLUSION Our study showed similar effects of MET and MI on BMI, body composition, hormonal profile, metabolism of glucose and insulin, and adiponectin level. The two insulin sensitizers, MET and MI, were useful in reducing BMI and improving body composition without significant differences between the two treatments in PCOS women. TRIAL REGISTRATION ISRCTN13199265. Trial registration date: 14.04.2021. (ISRCTN Registry), retrospectively registered.