Introduction: Diabetic nephropathy is one of the most frequent and serious complications of diabetes mellitus. This study was designed to evaluate the effect of green tea (GT) extract and low doses of 0.5 Gy γ-radiation (R) on diabetic nephropathy (DN) of rats. 
Materials and methods: Male Swiss albino rats were used in this study. DN was induced in rats using streptozotocin (45 mg/kg body weight). The rats were divided into five groups DN, DN+R, DN+GT, DN+GT+R and a sham treatment control group. Throughout the experimental period (3and 6 weeks) animals body weight, glucose and insulin levels were evaluated. Kidney functions assay (serum urea and creatinin) were recorded. Histopathological observations in kidney tissue, DNA and glycogen intensity were also detected.
Results: Diabetic rats exhibited many symptoms including loss of body weight, increase in blood glucose level and decrease in serum insulin levels. Increase in serum urea and creatinin levels. Diabetic kidney showed a moderate renal damage, multifocal clarifications and vacuolations. Carbohydrates intensity showed a significant increase and DNA intensity showed many alterations.   Improvements in glomerular and tubulointerstitial lesions were demonstrated in the diabetic rat group exposed to low doses of γ-radiation or supplemented by green tea either alone or combined in addition to amelioration in glucose, insulin urea and creatinin levels. 
Conclusion: The present study demonstrates the efficacy of low doses of γ- radiation and in reducing diabetes-induced functional and histological alterations in the kidneys. The longterm control of blood glucose levels using low doses of γ-radiation or green tea either alone or combined could prevent the progression of diabetes mellitus, and therefore, nephropathy could be prevented.