Background The present investigation focuses the diabetes-induced testicular hypofunction and its possible correction by the effective dose of ethyl-acetate fraction of methanolic extract of Camellia sinensis leaves through dose-dependent study in streptozotocin-induced diabetic rat. Methods The androgenic, spermiological, oxidative stress and apoptosis sensors along with testicular genomic sensors were evaluated in a dose-dependent fashion (50 mg or 100 mg or 200 mg/kg body weight). Activities of hepatic transaminases for toxicity assessment were also measured. Results Increased level of fasting blood glucose, testicular cholesterol, seminal vesicular fructose along with a low count, motility and viability of epididymal sperm, low activities of testicular Δ5, 3β-hydroxy steroid dehydrogenase (HSD), 17β-HSD, testicular antioxidant enzymes (catalase and superoxide dismutase) and low plasma level of testosterone were noted in diabetic rat in respect to the control. After oral administration of said fraction to diabetic rat, levels of above sensors were resettled toward the control. A significant decrease in the number of different generations of germ cells at the stage VII of spermatogenesis in diabetic rat was noted which were recovered significantly toward the control in the fraction-treated diabetic group. It was supported by the correction in gene expression of testicular Δ5, 3β- HSD, 17β- HSD, Bcl-2 and Bax in the fraction-treated diabetic group. Conclusions The threshold dose of ethyl-acetate fraction of methanolic extract of C. sinensis leaves is 100 mg/kg body weight for the recovery of testicular hypofunction in a diabetic rat model.