Evaluating the effect of insulin sensitizers metformin and pioglitazone alone and in combination on women with polycystic ovary syndrome: An RCT

Insulin resistance and hyperinsulinemia may play a role in pathogenesis of PCOS. One of the common therapeutic methods is using insulin-sensitizing drugs such as metformin and thiazolidinediones.

The purpose was to determine the effect of metformin and pioglitazone on clinical, hormonal and metabolic parameters in women with PCOS.

Eighty four women randomly received one of the following for 3 months: metformin (n=28) (500 mg three times a day), pioglitazone (30 mg daily) (n=28) and combination of both metformin and pioglitazone (n=28) (30 mg/day pioglitazone plus 500 mg metformin three times a day). Hormonal profile, fasting serum insulin, body weight, body mass index, menstrual status and waist to hip ratio were evaluated before and after treatment.

Metformin and pioglitazone and combination therapy induced favorable changes in fasting serum insulin, HOMA-IR index, QUICKI, fasting glucose to insulin ratio in women with PCOS. Body weight, BMI, and waist to hip ratio increased significantly after treatment with pioglitazone but the data were similar after administration of metformin or combination therapy. Total testosterone level decreased significantly only after treatment with metformin. After 3 months in patients who received pioglitazone or combination therapy, menstrual cycles became regular in 71.4% and 73.9% respectively. While menstrual improvement happened only in 36.4% of the patients treated with metformin.

These findings suggest that insulin-sensitizing drugs induce beneficial effect in insulin resistance and menstrual cyclicity but only metformin ameliorated hyperandrogenemia in women with PCOS. Treatment with combination of metformin and pioglitazone did not show more benefit than monotherapy with each drug alone.