GDF15 and Insulin resistance: The analysis (Table 3) revealed a significant and positive association between plasma GDF-15 levels and HbA1c (r = 0.297, p < 0.001), fasting blood glucose (FBG) (r = 0.269, p < 0.001), fasting insulin (r = 0.127, p < 0.001), and the homeostatic model of insulin resistance (HOMA-IR) (r = 0.198, p < 0.001).