Effect of metformin by employing 2-hour postload insulin for measuring insulin resistance in Taiwanese women with polycystic ovary syndrome

Background/purpose Evidence on clinical effectiveness of metformin in ethnic Chinese women with polycystic ovary syndrome (PCOS) remains scarce. Standard diagnostic approaches to identify insulin resistance (IR) cases in PCOS patients might be invasive, labor intensive, and stressful for patients (i.e., euglycemic clamp), or somewhat complicated for clinicians to calculate and monitor in routine practice [i.e., the homeostatic model assessment (HOMA) and quantitative insulin sensitivity check index (QUICKI)]. The aim of this study was to evaluate the clinical effects of metformin in Taiwanese women with PCOS and identify the feasible diagnostic measures of IR for Taiwanese women with PCOS. Methods A total of 114 women from a medical center in Taiwan were studied. All were aged between 18 years and 45 years, diagnosed with PCOS according to the Rotterdam criteria, and treated with metformin. Outcome end points were body mass index (BMI) and 2-hour postload glucose and insulin levels from a 75-g oral glucose tolerance test. Results BMI in overweight patients were significantly improved with metformin treatment duration (p < 0.001). The 2-hour insulin level statistically improved after treatment (before: 80.7 ± 63.9 μIU/mL vs. after: 65.0 ± 60.4 μIU/mL; p = 0.009). The improved 2-hour insulin level was significantly greater in IR patients than in non-IR patients. Compared with the 2-hour postload insulin level, the fasting insulin level provided 18.15% sensitivity and 94.12% specificity, the HOMA yielded 40% sensitivity and 70.58% specificity, and the QUICKI achieved 63.63% sensitivity and 11.76% specificity. Conclusion Clinical outcomes in Taiwanese PCOS women were improved with metformin treatment, especially in overweight and IR patients. The 2-hour postload insulin level appears to be a convenient tool for screening IR in Taiwanese patients.