Insulin Sensitization for Girls with Precocious Pubarche and with Risk for Polycystic Ovary Syndrome: Effects of Prepubertal Initiation and Postpubertal Discontinuation of Metformin Treatment

Among girls with precocious pubarche (PP), those with low birth weight (LBW) are, even if nonobese, at risk for progression to polycystic ovary syndrome (PCOS) including hyperinsulinemic hyperandrogenism, dyslipidemia, dysadipocytokinemia, and central fat excess. Recently, we disclosed the efficacy of insulin sensitization with metformin to disrupt progression from PP to PCOS in formerly LBW girls who were postmenarche. In LBW-PP girls, we have now extended the exploration of early insulin sensitization therapy in two directions: 1) metformin therapy was started before puberty; and 2) we assessed the effects of metformin discontinuation in girls who had started metformin treatment after menarche. Prepubertal LBW-PP girls (n = 33; mean age, 8.0 yr; body mass index, 18.5 kg/m(2)) were randomly assigned to remain untreated or to receive metformin (425 mg/d) for 6 months. Postpubertal LBW-PP girls (n = 24; age, 12.4 yr; body mass index, 21.0 kg/m(2)) had been randomized (at -12 months) to remain untreated or to receive metformin (850 mg/d) for 12 months, at which time (0 month) a treatment cross-over was performed for 6 months. Fasting blood glucose and serum insulin, SHBG, dehydroepiandrosterone sulfate, androstenedione, testosterone, lipid profile, IL-6, and adiponectin were assessed at 0 and 6 months, as was body composition (by dual x-ray absorptiometry). In the prepubertal study (group A), comparisons of untreated vs. treated girls disclosed normalizing effects of metformin on SHBG, androstenedione, dehydroepiandrosterone sulfate, low and high density lipoprotein cholesterol, triglycerides, IL-6, adiponectin, total and abdominal fat mass, and lean body mass. In the postpubertal study (group B), treatment cross-over at 0 month was in each subgroup followed by a striking reversal in the course of the endocrine-metabolic state, adipocytokinemia, and body composition; all changes pointed to normalizing effects of metformin treatment. In conclusion, these two studies provide the first evidence that 1) prepubertal metformin therapy has normalizing effects on PCOS features in high risk girls with a combined history of LBW and PP; and 2) in adolescence, metformin's normalizing effects are reversed as soon as metformin therapy is discontinued.