Interplay of Low Serum Irisin Level and Insulin Resistance in Obese Polycystic Ovary Syndrome Patients: Potential Biomarker for Pre-clinical Risk Assessment and therapeutic intervention

IntroductionPolycystic Ovary Syndrome (PCOS) is the most frequent endocrine syndrome in women of the reproductive age groupassociated with metabolic syndrome and TypeIIDiabetesMalitus (TIIDM). Purpose of the study was to evaluate if level of serum irisin which is involved in energy metabolism could be used as biomarker for identifying high risk category for pre-clinical detection of diabetes in PCOS. MethodsTotal 27 obese PCOS, 27 non-obese PCOS, and 27 healthy control (HC: 11 obese and 16 non-obese) study subjects between the age group 15-30 years were recruited in the study. Obese and non-obese category was divided based on BMI. Serum irisin, fasting insulin, fasting glucose and other reproductive hormonal profiles were estimated. Cut offs for serum irisin and insulin level were determined based on levels in healthy control. ResultNone of the subject was diagnosed having diabetes at the time of sampling. Both obese and non-obese PCOS showed non-significant lower irisin level than corresponding healthy control (42.27{+/-}31.38 vs 51.56{+/-}22.7,P=0.4 and 34.89{+/-}21.58 vs 40.90{+/-}16.444,P=0.4 respectively). However only obese PCOS showed statistically significant association with lower irisin level when median value of the corresponding healthy control was used as cut off (81.5% vs 45%, P=0.047* and 70.3% vs 50%,P=0.21 in PCOS vs HC of obese and non-obese group respectively). Segregating PCOS subjects into two category either normal or below the lower limit of normal serum irisin level(mean-1.64*z of corresponding HC), 100% of obese PCOS subjects having irisin below the lower normal limit showed insulin resistance (>mean+2SD of non obese HC) while the same in obese PCOS subjects having irisin level above the lower limit was only 20% (P=0.006). However no such association was observed in non-obese PCOS subjects when similarly categorized based on irisin level (33% vs 22% respectively, P= 1). ConclusionThe result suggests that obese PCOS with serum irisin level below lower limit of normal range could be segregated as high risk category for closely follow up to detect incidence of diabetes in early time point or taking any preventive measure in early stage. A prospective study with larger sample size is required to substantiate the observation of the pilot study.