GDF15 and diabetes mellitus: In the highest GDF-15 quartile, the adjusted OR of DR was 2.15 [95% confidence interval (CI) 1.53–3.02] after adjusting for age, gender, smoking, alcohol consumption, education status, physical activity, BMI, waist circumference, CRP, adiponectin, HOMA-IR, liver enzymes, diabetes duration, FPG, eGFR, Cr, and ACR.