Objective and design: YKL-40 is involved in inflammation and endothelial dysfunction, and is increased in patients with type 1 diabetes, with an independent association between increasing YKL-40 levels and increasing levels of albuminuria. YKL-40 is associated with atherosclerosis and an increased cardiovascular mortality in the general population. In the present study YKL-40 levels were examined in patients with type 2 diabetes (T2D) with increasing levels of albuminuria, known to be associated with an increased risk of cardiovascular disease.
Materials and methods: One-hundred-five patients with T2D were examined: 49 with normoalbuminuria (N, U-albumin/creatinine < 2.5 mg/mmol), 35 with persistent microalbuminuria (MA, 2.5-25 mg/mmol) and 21 with persistent macroalbuminuria/diabetic nephropathy (DN, > 25 mg/mmol). The control group consisted of 20 healthy individuals (C). Groups were matched according to age, gender and known duration of diabetes.
Results: Median levels (interquartile range) of serum YKL-40 were significantly higher in N and MA vs. C (86 (55-137) ng/ml and 84 (71-147) ng/ml, respectively vs. 41 (33-55) ng/ml, p < 0.01) and even higher in patients with DN (120 (83-220) ng/ml, p < 0.001 for all comparisons). YKL-40 levels correlated with urinary albumin/creatinine-ratio in the total group of participants (r = 0.41, p < 0.001). Significant intercorrelations of YKL-40 were found with age, duration of diabetes, systolic blood pressure, lipid levels, HbA1c and HOMA-IR. After adjustment for significant covariates, albuminuria was significantly associated with YKL-40 levels (r = 0.32, p = 0.006).
Conclusions: YKL-40 levels are elevated in patients with T2D with an independent association between increasing YKL-40 levels and increasing levels of albuminuria. The study suggests a role of YKL-40 in the progressing vascular complications in patients with T2D.