GDF15 and diabetes mellitus: Plasma levels of GDF15 were significantly higher in those who currently smoked than in those who did not, in those with hypertension than in those without, in those with DM than in those without, in those with metabolic syndrome than in those without, and in men than in women after adjusting for age, sex, BMI, and smoking (P ≤ 0.001, P = 0.002, P < 0.001, P = 0.021, and P = 0.023, resp).