Metformin effect on internal carotid artery blood flow assessed by area under the curve of carotid artery Doppler in women with polycystic ovarian syndrome

BACKGROUND Insulin resistance(IR) was reported in most polycystic ovarian syndrome(PCOS) cases. Metformin, a biguanide drug, successfully reduced IR. Homeostatic Model Assessment for IR(HOMA-IR) and Doppler parameters assessed metformin’s effectiveness.AIM To verify whether the area under the curve of the internal carotid artery(AUCICA) Doppler wave can be a useful marker for assessing IR among PCOS cases who presented with menstrual irregularity and were treated with metformin over 6 mo.METHODS An observational, cross-sectional study recruited 54 eligible PCOS women; the anthropometrics were as follows: age, body mass index(BMI), menstrual cycle days, biochemical serum cholesterol, low and high-density lipoprotein, sex hormone-binding globulin, fasting blood glucose, and HOMA-IR, hormonal testosterone, luteinizing hormone over follicle-stimulating hormone ratio, and ultrasonic pulsatility index(PI) and resistance index(RI), carotid artery intimamedia thickness(CIMT) and(AUC-ICA) parameters were initially recorded and repeated 3 mo and 6 mo later with metformin tab 500 mg; three times/day for 6 mo. In addition, AUC-ICA was assessed by taking repeated systolic and diastolic wave height measurements.RESULTS Metformin caused a progressive reduction in BMI, menstrual cycle days, biochemical hormonal, and Doppler parameters(CIMT, PI, RI, and AUC-ICA). AUC-ICA correlated strongly to all PCOS parameters. AUC-ICA correlated inversely with treatment time(r =-0.98, P < 0.001) and positively with HOMA-IR(r = 0.98, P < 0.0001). Via the best subset regression model, the AUC-ICA had the highest predictive value for HOMA-IR.CONCLUSION AUC-ICA preceded PI, RI, and CIMT with a strong, meaningful correlation to all PCOS parameters, making it a reliable marker for the assessment of IR, especially during metformin therapy. Further studies are recommended to promote the application in practice.