[Effect of long-term treatment with metformin on steroid levels and parameters of insulin resistance in women with polycystic ovary syndrome].

BACKGROUND

Insulin resistance is probably the key factor in the pathogenesis of polycystic ovary syndrome, and thus insulin sensitization can be a beneficial treatment. We tried to investigate effects of long-term therapy with metformin in polycystic ovary syndrome on steroid levels, ovarian steroidogenesis and on insulin resistance and secretion. We also tried to find predictors of the successful therapy (in terms of improvement of menstrual cyclicity).

METHODS AND RESULTS

24 oligo/amenorhoeic women with polycystic ovary syndrome were included into the study. Basal blood samples were taken for the determination of testosterone, estradiol, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone-sulphate, 17OH progesterone, 17OH pregnenonole, sex-hormone binding globulin and cortisol. Gonadoliberin (GnRH) analogue test was performed with estimation of the same steroids and LH. Oral glucose tolerance test was done with dextrose, and with estimation of glucose, insulin, and C peptide. HOMA model assessment was used for calculation of insulin resistance and insulin secretion. All examinations were done before and after 27 +/- 4 weeks (average +/- standard deviation) of therapy with metformin 1000 mg/day. Significant improvement in menstrual cyclicity was observed in 58% of women. No significant change in basal steroid levels was found. A trend towards decline in insulin resistance and secretion was detected. Significant decrease in the mean stimulated testosterone level (from 1.74 to 1.54 nmol/l, 95% CI 1.42-2.08 and 1.21-1.87; p < 0.05), 17OH progesterone level (from 3.32 to 2.37, 95% CI 1.42-2.08 and 1.21-1.87; p < 0.05), LH (from 9.1 to 4.8 IU/l, 95% CI 6.4-12.8 and 3.4-6.8; p < 0.05), and estradiol level (from 0.91 to 0.43 nmol/l, 95% CI 0.69-1.19 and 0.38-0.65; p < 0.01) were detected. The best prediction of the improvement in menstrual cyclicity after metformin was achieved with the combination of basal 17OH progesterone, androstendione, testosterone and SHBG. This model correctly classified 86.7% of subjects.

CONCLUSIONS

Long-term therapy with metformin led to the improvement in menstrual cyclicity, without significant change in basal steroid levels or parameters of insulin resistance.