Objective:To observe the protective effect of deproteinized extract of calf blood (DECB) on the kidney injury of the diabetic rats, and to discuss its mechanism preliminarily.Methods:The male Wistar rats were intraperitoneally injected with STZ (65 mg·kg-1) to establish the diabetes models, then the model rats were randomly divided into model (M)group, and metformin (MMet, 105 mg·kg-1) group , low dose of combined administration (ML,105 mg·k-1 metformin+94.5 mg·kg-1 ,DECB) group, medium dose of combined administration(MM, 105 mg·kg-1 metformin+ 189 mg·kg-1 DECB) group, high dose of combined administration(MH, 105 mg·kg-1 metformin +378 mg·kg-1,DECB) group, another ten Wistar rats were selected as normal control(NC)group.The rats were intragastrically administed with metformin and intraperitoneally injected with DECB, once a day, total of 8 weeks.The rats in NC group and M group were given normal saline solution.The weights and blood glucose levels of the rats in various groups were determined;the levels of serum high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), blood urea nitrogen (BUN), urinary albumin (UAlb), urine creatinine (UCR), serum creatinine (SCr), total cholesterol (TC), triglyceride (TG), uric acid (UA), glutathione (GSH), and malondialdehyde (MDA) were detected;the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were determined.The pathological changes of kidney tissue of the rats in various groups were detected by HE staining.Results:Compared with NC group, the weight of the rats in M group was reduced(P<0.05),and the levels of blood glucose,UAlb,UCr,SCr,UA,BUN,LDL-C,TC,TG,and MDA were increased(P<0.05);the levels of HDL-C and GSH were obviously reduced(P<0.05),and the activities of SOD adn GSH-Px were obviously reduced(P<0.05).Compared with M group,the weights of the rats in MM and MH groups were increased (P<0.05), and the levels of blood glucose,UAlb,UCr,SCr,UA,BUN,LDL-C,TC,TG, and MDA were decreased (P< 0.05);the levels of HDL-C and GSH were increased (P<0.05),and the activities of SOD and GSH-Px were increased (P<0.05).The pathological observation of kidney tissue showed that the rats in M group had obvios kidney tissue lesions with glomerular congestion and renal tubular edema compared with NC group;compared with M group,the pathological changes of the kidney tissue of the rats in drug administration groups were significantly improved, the renal tubular vacuoles were reduced, and the interstitial hyperplasia was not obvious.Conclusion:DECB combined with metformin can reduce the blood glucose level, regulate blood lipid, improve the pathological changes of kidney tissue in the diabetic rats, reduce the renal damage, and enhance the antioxidant capacity of the body.