Abstract:Objective To explore the relationship of urinary Smad1 with early diagnosis and progression of diabetic nephropathy in type 2 diabetes patients. Methods In this study 166 subjects with type 2 diabetes and 80 healthy volunteers were enrolled. The patients were divided into three groups according to urine albumin to creatinine ratio, i.e. normal albuminuria group, microalbuminuria group and macroalbuminuria group. The 80 healthy volunteers were the controls. Enzyme-linked immunosorbent assay was used to detect the urinary Smad1 concentration. Urinary Smad1 to creatinine ratio (SCR) was used as the standard reference. Results The SCR in the microalbuminuria group was higher than that in the normal albuminuria group (P < 0.05). SCR of the macroalbuminuria group was higher than that of the microalbuminuria group (P < 0.05), while there was no difference between the normal albuminuria group and controls (P > 0.05). Pearson correlation analysis showed that SCR was positively correlated to HbA1c, duration and diabetic retinopathy of the disease (r = 0.384, 0.413 and 0.325; P = 0.000, 0.005 and 0.021, respectively). ROC curve showed that urinary Smad1 is a good indicator for early diagnosis of type 2 diabetic nephropathy. Conclusions Urinary Smad1 may be a new early diagnostic indicator for diabetic nephropathy and could reflect the progression of diabetic nephropathy.