Materials and Methods: In a single-blind clinical trial, 96 patients with abnormal uterine bleeding and endometrium with irregular or hyperplastic glands with or without atypical foundations were divided randomly into 2 equal groups. Group1 received metformin 500 mg twice a day plus megestrol acetate 40 mg daily for 3 months and group 2 received megestrol acetate 40 mg/d for 3 months. The treatment response was evaluated using pathologic samples of endometrial biopsies 2 weeks after completing the treatment.

Results: In both groups, endometrial hyperplasia was resolved in most cases. Significant decrease was observed within groups in the endometrial thickness before and after the intervention. Comparison of thickness between 2 groups showed that in the megestrol acetate group, after intervention, significant decrease in the endometrial thickness was revealed (12.73 ± 6.04 mm [group 1], versus 8.55 ± 3.43 mm [group 2], P < 0.001). Lack of response to treatment was seen in 7% of group 1 and 4.9% of group 2 (P=0.68). None of the groups showed any complications and there was no hysterectomy.

Conclusions: Both treatment modalities were effective in treating proliferative and hyperplastic disorders. However, the response to treatment in the megestrol group was greater than that in the megestrol plus metformin group.