Abstract: Objective: To evaluate the role of vitamin D in the pathogenesis of type 2 diabetic nephropathy(T2DN) by observing the changes of blood serum vitamin D and biochemical markers of renal function in patients with T2DN.Methods: According to 24 h urinary albumin excretion(24 h-UAE),72 hospitalized patients with T2DN were divided into normal albuminuria group(group A),microalbuminuria group(group B)and macroalbuminuria group(group C),and 22 healthy people were selected as control(group D).the levels of urea(UREA),creatinine(Cr),uric acid(UA),24 h-UAE and serum 25-(OH)D₃ were detected;The levels of serum 25-(OH)D₃ and biochemical indexes were analyzed and compared among the four groups.Results: The level of serum 25-(OH)D₃ in group A,group B and group C was significantly lower than that in group D(P <0.01);the level of serum 25-(OH)D₃ in group C was significant lower than that in group A and group B(P <0.01),but the difference was not significant between group A and group B(P>0.05).The level of plasma UREA,Cr and 24 h-UAE in group C were significantly higher than that in group D,group A and group B(P<0.01);but the difference was not significant between group A and group B(P>0.05).The four groups demonstrated no significant difference in UA(P>0.05).Serum 25-(OH)D₃ was negatively related to UREA,Cr and 24 h-UAE(P<0.05),and there was no relationship between 25-(OH)D₃ and UA(P>0.05).Conclusions: T2DN patients complicated with 25-(OH)D₃ deficiency are more prone to kidney diseases.