Abstract: Objective To explore the effect of vitamin D combined with Siglitatin on urinary protein level, bone mineral density and bone metabolism in patients with type 2 diabetic nephropathy. Methods From January 2016 to January 2018, 114 patients with type 2 diabetic nephropathy in our hospital were divided into two groups according to the random number table method, 56 cases in the control group and 58 cases in the experimental group. All patients were given routine treatment such as hypoglycemia. On this basis, the control group was given vitamin D treatment, and the experimental group was given vitamin D combined with Siglitatin treatment. The urinary albumin excretion rate (UAER), urinary beta 2-microglobulin (beta 2-MG), urinary microalbumin (mA1b), bone mineral density (L₂-L₄, femoral neck, Ward triangle, femoral trochanter, hip joint), serum calcium, phosphorus, 25-hydroxyvitamin D (25-OH-D₃), parathyroid hormone (PTH), bone gla protein (BGP), procollagen type I N propeptide (PINP) and C-terminal telopeptides of type I collagen (β-CTX) were compared between the two groups after treatment. Results After treatment, UAER, urinary beta 2-MG and 24-hour urinary albumin levels in the experimental group were lower than those in the control group (P<0.05). After treatment, the bone mineral density of each detection site in the experimental group was higher than that in the control group (P<0.05). The serum calcium of the experimental group were higher than those of the control group , and the serum phosphorus of the experimental group were lower than those of the control group (P<0.05). After treatment, the levels of 25-OH-D₃ and PINP in the experimental group were significantly higher than those in the control group (P<0.05), and PTH, BGP and beta-CTX in the experimental group were significantly lower than those in the control group (P<0.05). The total incidence of adverse reactions in the control group and the experimental group were 8.93% and 12.07%, respectively, with no significant difference (P=0.585). Conclusion In the treatment of type 2 diabetic nephropathy, vitamin D combined with Siglitatin can effectively reduce urinary protein, increase bone mineral density and improve bone metabolism in patients with better safety.