Metformin and Gestational Diabetes in High-risk Patients: a RCTs

Obese pregnant PCOS patients with previous diagnosis of gestational DM will be enrolled and allocated into two treatment arms (experimental and placebo groups). Subjects in the experimental group will receive metformin at dosage of 850 mg twice daily, whereas subjects in the control group will receive placebo tablets (microcristallyne cellulose) twice daily.

At baseline, all subjects will undergo clinical evaluation, serial ultrasound examinations, and venous blood drawing to evaluate complete hormonal assays and serum fasting glucose and insulin levels. The homeostasis model of assessment-insulin resistance, the fasting glucose-to-insulin ratio, and the free androgen index will be also calculated. Monthly follow-up visits will be performed for assessing maternal and fetal wellbeing.

The primary endpoint of the study will be the incidence of gestational DM. The power analysis and the sample size calculation, performed using SamplePower release 2.0, showed that we will need to enroll at least 40 patients for each group to yield a statistically significant result with a power study of 90%. For categorical variables, the Pearson chi-square test will be performed. Continuous data will be expressed either as mean and standard deviation or median and inter-quartile range with min-max values, according to their normal distribution, and analysed using the Student t test or Mann-Whitney U test, respectively. Statistical significance will be set at P<0.05. The Statistics Package for Social Science (SPSS 14.0.1; Chicago, IL, USA) will be used for statistical analysis.