Acute effects of metformin therapy include improvement of insulin resistance and ovarian morphology.

OBJECTIVE

To evaluate the acute effects of metformin therapy on biochemical markers and polycystic ovarian morphology among insulin-resistant (IR) and noninsulin-resistant (NIR) patients with polycystic ovary syndrome (PCOS).

DESIGN

Prospective interventional study.

SETTING

Reproductive endocrinology clinic in a university hospital.

PATIENT(S): Five IR and five NIR patients with PCOS. The mean age of patients was 29.5 +/- 4.8 years (range, 23-36 years).

INTERVENTION

Metformin therapy, using 850 mg orally per day for 1 week.

MAIN OUTCOME MEASURE(S): Serum levels of T, FSH, and LH, fasting glucose/insulin ratio, levels of anti-Müllerian hormone (AMH) and inhibin B, and antral follicle count.

RESULT(S): Levels of AMH and inhibin B were statistically significantly higher in patients with PCOS compared to controls (2.81 +/- 1.79 ng/mL versus 0.95 +/- 1.17 ng/mL, and 56.24 +/- 29.39 pg/mL versus 17.89 +/- 12.87 pg/mL, respectively). Levels of AMH and inhibin B were similar among IR and NIR patients with PCOS (2.77 +/- 1.92 ng/mL versus 2.85 +/- 1.89 ng/mL, and 53.96 +/- 28.58 pg/mL versus 58.51 +/- 33.28 pg/mL, respectively). One week of metformin therapy did not alter either AMH or inhibin B levels. However, there was a statistically significant increase in glucose/insulin ratios (4.59 +/- 1.57 versus 6.35 +/- 3.6), and a significant decrease in the number of antral follicles after 1 week of metformin therapy (38.8 +/- 19.3 versus 23.1 +/- 7.4).

CONCLUSION(S): Levels of AMH and inhibin B are significantly increased in patients with PCOS compared to controls, but are not associated with insulin resistance. Low-dose metformin therapy improves IR and polycystic ovary morphology, even though levels of T, AMH, and inhibin B remain unchanged.