GDF15 and diabetic retinopathy: After adjusting for sex, age, hyperlipidemia, hypertension, hs-CRP, BMI, HbA1c, DM duration, eGFR, AER, and the use of insulin and OHAs, there was a significant difference in the average GDF-15 plasma levels according to the degree of diabetic retinopathy (no diabetic retinopathy, 1114 ng/L, 95% CI: 1033–1199; NPDR, 1327 ng/L, 95% CI: 1143–1538; PDR, 1445 ng/L, 95% CI: 1161–1803; p for trend = 0.035).