The impact of obesity and insulin resistance on the outcome of IVF or ICSI in women with polycystic ovarian syndrome

The impact of insulin resistance on the outcome of IVF or intracytoplasmic sperm injection (ICSI) in women with polycystic ovarian syndrome (PCOS) was examined. Insulin sensitivity was measured by the continuous infusion of glucose with model assessment (CIGMA) test. Insulin-resistant (n = 26) and non-insulin-resistant women (n = 30) with PCOS underwent a total of 100 cycles of long-term down-regulation with buserelin acetate, stimulation with human recombinant FSH, and IVF or ICSI. Blood samples were taken throughout ovarian stimulation for hormone assays. Insulin-resistant and non-insulin-resistant women had similar concentrations of FSH, LH, testosterone and androstenedione throughout stimulation, but insulin-resistant women had hyperinsulinaemia and lower sex hormone binding globulin concentrations. Insulin-resistant women also had lower oestradiol concentrations during stimulation and required higher FSH doses, but these differences disappeared after controlling for the higher body weight in the group of insulin-resistant women. Groups had similar number of oocytes collected, similar implantation and pregnancy rates, and the incidence of ovarian hyperstimulation syndrome was also similar. Obesity, independent of hyperinsulinaemia, was related to a lower oocyte count and increased FSH requirement. It is concluded that in PCOS women receiving long-term down-regulation and stimulation with recombinant FSH, insulin resistance is neither related to hormone levels nor to IVF outcome. Obesity, independent of insulin resistance, is associated with relative gonadotrophin resistance.