Urinary type IV collagen as a predictor for the incidence of microalbuminuria in young patients with Type 1 diabetes

AimsTo clarify whether urinary type IV collagen-to-creatinine ratio is a predictor for the incidence of microalbuminuria in patients with Type1 diabetes. MethodsA longitudinal observational cohort study was conducted; the subjects included normoalbuminuric patients diagnosed with Type1 diabetes before the age of 30years and who were less than 40years old at the start of the observation. In total, 225 patients were enrolled (age, meanSD: 255years; male: 32.9%). The endpoint was the incidence of microalbuminuria, defined as 30 mg/g Cr urinary albumin-to-creatinine ratio < 300 mg/g Cr. Patients were divided into two groups based on the median of urinary type IV collagen-to-creatinine ratio levels. ResultsDuring the median follow-up period of 8.8years (range 1.0-12.8years), 13 patients with high urinary type IV collagen-to-creatinine ratio progressed to microalbuminuria. Meanwhile, only one patient with low urinary type IV collagen-to-creatinine ratio reached the endpoint. Kaplan-Meier estimates for the time to reach the endpoint were significantly faster for patients with a high ratio than for those with a low ratio (log-rank test, P<0.001). In the multivariate Cox hazard analysis, the hazard ratio for patients with high vs. low urinary type IV collagen-to-creatinine ratio was 13.51 (95%CI 1.59-115.02, P=0.017). When urinary type IV collagen-to-creatinine ratio was treated as a continuous variable, logarithmically transformed urinary type IV collagen-to-creatinine ratio, but not baseline albumin-to-creatinine ratio, was independently associated with reaching the endpoint (hazard ratio19.23, 95%CI 1.53-242.30, P=0.022). ConclusionsUrinary typeIV collagen may be an important predictor for the incidence of microalbuminuria in young patients with Type1 diabetes.