GDF15 and diabetes mellitus: In addition, the serum GDF15 levels were also positively correlated with age (r = 0.205, P < 0.001), BMI (r = 0.179, P < 0.001), FCP (r = 0.110, P = 0.033), HOMA2-IR (r = 0.103, P = 0.046), TG (r = 0.130, P = 0.012), and diabetes duration (r = 0.257, P < 0.001), but negatively correlated with TC (r = − 0.214, P < 0.001), LDL-c (r = − 0.206, P < 0.001), and HDL-c (r = − 0.142, P = 0.006).