〔Abstract〕 Objective To investigate the effects of long-term hyperglycemia on renal pathology of type 1 diabetic mellitus(T1DM) cynomolgus monkeys by establishing streptozotocin(STZ)-induced T1DM. Methods Eight 4-year-old male cynomolgus monkeys were randomly divided into control and model groups. Four cynomolgus monkeys were used in the control group, and four cynomolgus monkeys were injected with streptozotocin to create a T1DM model. Hematoxylin-eosin(HE) staining and periodic acid-Schiff(PAS) staining were used to observe renal pathological changes.The histological characteristics and changes were observed under transmission electron microscope. Morphometric measurements were used to analyze the glomerular area, the thickness of the glomerular basement membrane, the proportion of glomerular podocyte foot processes and the average area of foot processes. Results In comparison to the control group, the model group showed pathological changes in the kidneys, including increased glomerular area(P<0.01), thickened basement membrane, capillary loop compression, disordered arrangement of endothelial cell fenestrations, proliferation of mesangial cells, mesangial expansion, accumulation of mesangial matrix glycoproteins, a decrease in the number of foot processes(P<0.001), a decrease in the average size of the foot processes(P<0.05), widened podocyte slit diaphragm, and an increase in the number of fused foot processes(P<0.001). Conclusion Cynomolgus monkeys with T1DM suffer from renal pathological changes due to long-term hyperglycemia.