Objective:To examine the correlations of microRNA-34c(miR-34c) expression in the peripheral blood with the onset of diabetic foot ulcer(DFU)and diabetic foot osteomyelitis(DFO)in patients with type 2 diabetes mellitus(T2DM).Methods:Sixty newly-diagnosed T2DM patients without DFU(T2DM group), 112 T2DM patients with DFU(DFU group), and 60 healthy controls with normal glucose tolerance(NC group)were included. The 112 T2DM patients with DFU were further divided into DFO( n=64)and NDFO( n=48)groups. The levels of miR-34c were determined by quantitative real-time PCR, while clinical features and risk factors of DFU and DFO were explored. Results:A significant increase in the expression level of miR-34c in peripheral blood was observed in T2DM group compared with NC group[2.99(1.45-6.22) vs 1.01(0.89-1.52), P<0.05], and a markedly increased miR-34c expression level was noted in DFU group compared with T2DM group [9.65(6.15-18.63) vs 2.99(1.45-6.22), P<0.01]. Additionally, the expression level of miR-34c in peripheral blood significantly increased in DFO group compared to NDFO group [13.46(8.89-19.11) vs 6.02(5.93-14.72), P<0.01]. Moreover, there was a positive correlation between the expression level of miR-34c in peripheral blood and the amputation rate in patients in DFU group( P=0.030), and a negative correlation in the expression level of miR-34c( P=0.025)with healing rate of DFU after eight weeks. The multivariate logistic regression analysis confirmed that a high expression of miR-34c was an independent risk factor for DFU and DFO( OR=3.52, 4.13; both P<0.01). Conclusion:An increased expression of miR-34c in peripheral blood of T2DM patients might be closely related to the occurrence, development, and prognosis of DFU and DFO.