OBJECTIVE:To probe into the effects of C-peptide on bone tissue metabolism and osteogenesis in rats with type 2 diabetic osteoporosis（T2 DOP）.METHODS:T2 DOP model of female rats were established and randomly divided into sham group

T2 DOP group and C-peptide group（8 weeks and 12 weeks）

C-peptide group（8 weeks） and C-peptide group（12 weeks） were given C-peptide by subcutaneous injection for 8 weeks and 12 weeks

respectively.Glucometer was used to detect the blood glucose level of rats

kit was used to detect the contents of calcium

phosphorus and urinary deoxypyridinoline（DPD） in serum and urine of rats

and the content of alkaline phosphatase（ALP）

procollagen I N-terminal peptide（PINP）

carboxy-terminal telopeptide-I（CTX-I） and osteocalcin（OCN） in serum were detected;the bone density

bone microstructure and bone biomechanical characteristics of rats were analyzed by dual energy X-ray method

Viva CT and universal testing machine.RESULTS:T2 DOP model of rats were successfully established.Compared with T2 DOP group

the blood glucose

calcium

phosphorus and DPD levels in urine of C-peptide group were significantly reduced

the calcium

phosphorus

and PINP levels in serum of C-peptide group were significantly increased

the ALP and CTX-I levels in serum of C-peptide group were significantly reduced

the femoral bone density of C-peptide group was significantly increased

the bone microstructure parameters BV/TV

BS/BV

Tb.N and Conn.D of C-peptide group were significantly increased

the Tb.Sp and structure model index（SMI） of C-peptide group were significantly decreased

with statistically significant differences（P<0.05）.Compared with T2 DOP group

the OCN level in serum of C-peptide group（12 weeks） was significantly decreased

and the maximum load and elastic modulus were significantly increased

with statistically significant differences（P<0.05）.CONCLUSIONS:C-peptide can effectively decrease the blood glucose level

improve bone tissue metabolism

promote osteogenesis

slow down or even reverse T2 DOP-inducing bone resorption

increase femoral bone density

protect the damage of bone microstructure from T2 DOP and recover bone strength

and the effect of C-peptide treatment for 12 weeks is more significant.