Urinary excretion of type IV collagen in non-albuminuric and albuminuric patterns of chronic kidney disease in subjects with type 2 diabetes

Urinary excretion of type IV collagen (Col4), a component of glomerular and tubular basement membrane and mesangial matrix, is considered to be a promising marker of kidney fibrosis. This study aimed to assess the difference in the urinary excretion of Col4 in patients with type 2 diabetes (T2D) and non-albuminuric and albuminuric patterns of chronic kidney disease (CKD). This observational, single-center, cross- sectional study included 140 adult participants (males and females) with T2D duration above 10 years. Twenty adult individuals without diabetes were acted as healthy control. The concentration of Col4 was assessed in morning urine samples by ELISA. The patients with T2D had elevated levels of urinary Col4 excretion (p=0.002 vs. control). This difference was significant in patients with albumiuria with preserved renal function (p=0.03 vs. control) and albiminuric CKD (p=0.002 vs. control). The urinary excretion of Col4 was associated with urinary albumin/creatinine ratio (r=0.34, p<0.001), but not with estimated glomerular filtration rate (r<0.20, p>0.05). Some other factors also demonstrated associations with urinary Col4: female sex (p=0.02), age (r=0.33, p<0.001), and diabetes duration (r=0.27, p=0.001). The albuminuric patterns of CKD were associated with urinary excretion of Col4 (OR=2.53, 95% CI 1.11–5.76, p=0.03) after adjustment on serum triglyceride levels, age, sex, duration of diabetes, and body mass index. The results demonstrate that elevated urinary excretion of Col4 in T2D subjects is associated with albuminuric, but not with non- albuminuric pattern of CKD.