Issue 129 Item 12 Short-term Oral Progestin Reduces Insulin Sensitivity in PCOS

Short-term oral treatment with medroxyprogesterone acetate significantly improves insulin sensitivity, according to results of a prospective study. Dr. Tayfun Bagis and associates of Baskent University in Adana randomly assigned 10 reproductive age patients with PCOS to treatment with oral medroxyprogesterone acetate 10 mg/d. Ten were assigned to oral micronized progesterone 300 mg/day, and eight to vaginal micronized progesterone 600 mg/d.

As noted in their report in The Journal of Clinical Endocrinology and Metabolism for October, treatment in all three groups lasted for 10 days. Morning fasting blood samples were collected at baseline and on the first day of progesterone-induced menstruation, 12 to 14 days later.

Only oral medroxyprogesterone significantly reduced mean basal insulin levels (from 123 pmol/L to 87 pmol/L, p = 0.021). In this treatment group, insulin sensitivity also improved as measured by the homeostasis model assessment (HOMA) and a quantitative insulin sensitivity check index (QUICKI) (p = 0.021 for both).

In addition, medroxyprogesterone led to significant reductions in LDL cholesterol (p = 0.038) and lipoprotein (a) (p = 0.043).

Micronized progesterone also led to reductions in insulin and increases in insulin sensitivity, but these changes did not reach statistical significance. Vaginal administration of micronized progesterone appeared to have no effect on these measures.

Short-term oral micronized progesterone and especially oral medroxyprogesterone acetate may be used for the management of PCOS, Dr. Bagis’ team concludes. They remind physicians that such treatment may affect luteinizing hormone, total testosterone and insulin levels, so these parameters should not be evaluated until some time after progesterone treatment has concluded.

"The effects of long-term cyclic progesterone treatment should be clarified with further studies in PCOS patients," they add. J Clin Endocrinol Metab 2002;87:4536-4540.