Objectives: The most prevalent cause of chronic kidney disease is diabetic nephropathy (DN), which can lead to end-stage renal disease (ESRD) and premature death in developed countries but knowledge about these changes is still unsatisfactorily. Specific factors can be used to study developmental pathways and changes in rat diabetic kidneys. Snail is a superfamily of genes that has been found to control gastrulation and neural crest EMT through E-cadherin down-regulation. Snail is located in the fibroblast growth factor receptor 1 (FGFR1) and has a regulatory role in kidney physiology by involvement in the pathway downstream of MAPK and Ras GTPase. The aim of the study was to analyse whether prolonged DM induces changes in immunofluorescence expression of Snail in rat’s kidney and how it contributes to DN during ageing. Materials and methods: Diabetes mellitus (DM) was induced by i/p injecting 55 mg/kg streptozotocin (STZ) to male Sprague-Dawley rats, and was validated by measuring blood glucose level. Control group received citrate buffer. Animals were sacrificed after 2 weeks and 2 months. Cortex areas (glomeruli, proximal and distal tubules) and medullary areas (collecting ducts and distal tubules) were analysed with antibodies raised against Snail. Results: Snail expression is mostly located within cortex in the proximal tubules. Strong intensity of Snail expression can be seen in proximal tubules in control in both 2 weeks and 2 months’ groups, while in both diabetic groups Snail staining intensity was mild. In the proximal tubules, the highest percentage of Snail positive cells was observed in 2-weeks control group (90%). Snail positive cells can also be found in the collecting ducts but the percentages remain very low there with 8% for the 2 weeks control group decreasing mildly to 7% after 2 months and with 2% in the 2 weeks diabetic group. Snail staining of collecting ducts is absent after 2 months in the diabetic group. Conclusion: Our findings suggest that Snail is linked to regulatory functions in kidney’s proximal tubules and that the loss of Snail expression in diabetic kidneys can lead to advanced DN. This finding can contribute to better understanding of the pathogenesis of DN during short-term DM.