Introduction: There is a need to develop diabetic animal model, to have a better understanding of the complications of diabetes mellitus. The dose of Streptozotocin (STZ) to induce diabetes mellitus in animals is important as it may lead to inadequate induction of diabetes or mortality. Intravenous injection of STZ in adult Wistar rats, leads to the degeneration in Langerhans islet β-cells and induces experimental diabetes mellitus in 3-5 days. Aim: To optimise the dose of STZ to create a diabetic animal model with sustained hyperglycaemia and to compare the changes in body weight, serum glucose and C-peptide levels between non diabetic and diabetic rats. Materials and Methods: This experimental animal study was conducted at animal house, Pal amur Bioscience Pvt., Ltd. The sample size included 30 albino Wistar rats divided into five groups T0, T1, T2, T3 and T4 with six rats in each group (three males and three females). Group T0 was the control, while STZ at different concentrations were administered intraperitoneally in group T1, T2, T3 and T4, respectively. Blood samples were drawn from retro-orbital plexus of animals and blood glucose, C-peptide levels along with the body weight was checked on 7th, 14th, 21st and 28th day. The F statistics, one-way Analysis of variance (ANOVA) was used to compare the different groups. Denny’s test was used to compare the control group versus different test groups. Results: When compared with the control group T0 on 7th, 14th, 21st and 28th day, the test group T1 had no variation in the body weight. On the other hand groups T2, T3 and T4 had variations in the body weights. Initially there was increase in the weight, later here was a gradual decrease in the body weight when compared to the control group. Hyperglycaemic profile (blood glucose level >120 mg/dL) was achieved in group T1, T2, T3 and T4 after 7 days. High mortality rate was observed in group T4 followed by group T3. Group T2 had persistent hyperglycaemia while group T1 had reversible hyperglycaemic profile. The C-peptide levels were gradually decreased in the test groups and it was statistically significant (p-value <0.0001). Conclusion: Intraperitoneal dose of STZ of 55 mg/kg created diabetic animal model with persistent hyperglycaemia. However, dose above increased the mortality rate and below failed to create diabetic animal model.

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