Effects of metformin and rosiglitazone, alone and in combination, in nonobese women with polycystic ovary syndrome and normal indices of insulin sensitivity

Objective

To determine whether insulin-sensitizing drugs would improve ovulation and T levels in women with polycystic ovary syndrome (PCOS), without clinical or biochemical criteria indicating insulin resistance and whether the combination of two distinct insulin-sensitizing drugs would be of any benefit over either drug alone.

Design

Randomized controlled double-blind trial.

Setting

A referral center in Caracas, Venezuela.

Patient(s)

One hundred twenty-eight nonobese PCOS women with normal indices of insulin sensitivity—that is, normal glucose tolerance, fasting insulin, peak insulin during an oral glucose tolerance test (OGTT), and fasting glucose-to-insulin ratio. Twenty-eight women were lost to follow-up initially and did not receive any intervention.

Intervention(s)

One hundred women received twice daily one of the following for 6 months: metformin (850 mg), rosiglitazone (4 mg), combination of both drugs, or at least one placebo.

Main outcome measure(s)

Frequencies of ovulation and serum free T after 6 months.

Result(s)

Frequencies of ovulation were higher after treatment with an insulin-sensitizing drug (ovulations per subject in 6 months: metformin, 3.3; rosiglitazone, 2.4; and combination, 3.4) than with placebo (0.4). Ovulatory frequencies increased significantly more with metformin than rosiglitazone, and the combination was not more potent. After treatment, serum free-T levels were comparable among all active treatment groups (metformin: 2.34 pg/mL, rosiglitazone: 3.06 pg/mL, and combination: 2.39 pg/mL) and were significantly lower than in the placebo group (7.26 pg/mL). Compared with placebo, fasting insulin levels, area under the insulin curve during OGTT, the homeostatic model assessment of insulin sensitivity, and OGTT-derived insulin sensitivity index improved significantly after metformin or combination therapies but not after rosiglitazone.

Conclusion(s)

These findings suggest that insulin-sensitizing drugs increase ovulatory frequency and ameliorate hyperandrogenemia, even in nonobese women with PCOS who appear to have normal insulin sensitivity.