INS and type 2 diabetes mellitus: In concordance with our finding in PCOS, fetuin-A levels were reported to be elevated in insulin-resistant T2D subjects, positively correlated with insulin resistance markers such as HOMA-IR, glycated hemoglobin, low-density lipoprotein cholesterol, BMI, and negatively correlated with fasting insulin, high-density lipoprotein cholesterol, and HOMA-β-cell insulin secretion index (25), and fetuin-A was shown to antagonize insulin action at cellular levels with direct inhibition of insulin binding to its receptor (26, 27).