Introduction: Polycystic ovary syndrome (PCOS) affects 12-21% of reproductive aged women1 2 and is associated with reproductive abnormalities, insulin resistance (IR) and elevated risk factors for cardiovascular disease and Type 2 diabetes3 4 5. The aetiology of PCOS remains controversial, with IR implicated in the pathophysiology of the condition6. Up to 85% of women with PCOS have some degree of IR that occurs independently of, yet is exacerbated by obesity7. The present study aimed to assess circulating biomarkers ghrelin, resistin, visfatin, glucagon-like peptide- 1 (GLP-1), leptin, plasminogen activator inhibitor-1 (PAI-1), gastric inhibitory polypeptide (GIP) and C-Peptide, as they play pivotal roles in body weight regulation, glucose homeostasis, insulin sensitivity and lipid metabolism, directly relevant to PCOS. Methods: In a mechanistic observational study, 84 premenopausal women with (n = 44) and without (n = 40) PCOS were recruited and further divided into groups based on PCOS and BMI status (lean control (n = 22), lean PCOS (n = 22), overweight control (n = 18) and overweight PCOS (n = 22). Hyperinsulinemic clamp studies and biomarker assays were completed. Results: Overall women with PCOS were more IR (clamp glucose infusion rate [mean±SD] 313±89 vs. 330±90 mg.min-1m2 P<0.05), had elevated testosterone, fasting androgen index and LDL:HDL ratio and lower fasting GIP levels (P<0.05). When investigating the relationships with PCOS and obesity, it was demonstrated that lean controls were the least IR, followed by lean PCOS (Effect size [ES] = 0.9), overweight controls (ES = 1.0) and overweight PCOS (ES = 2.0). C-peptide was elevated in the overweight PCOS group (0.3 ± 0.3 ng/ml) compared to lean control (0.2 ± 0.1 ng/ml; P = 0.02) and lean PCOS groups (0.1 ± 0.16 ng/ml; P=0.01). Lower ghrelin and higher leptin levels were found in overweight women irrespective of PCOS status compared to lean women. Glucose infusion rate, measured by the hyperinsulinemic clamp, predicted PAI1 and C-peptide levels, while BMI predicted leptin levels. Conclusion: The selected biomarkers measured to assess metabolic disease risk, appear more strongly associated with BMI status and insulin resistance than with PCOS status.