Background: The clinical exploration and regulatory approval of herbal formulations requires authenticated preclinical studies. Objectives: This study objective is to assess the therapeutic effectiveness of Insuwin and Insuwin forte polyherbal tablet formulation (Manufactured by SKM Siddha and Ayurveda Company (India) Pvt. Ltd.,) in diabetic rats. Materials and Methods: Hypoglycemic effect of Insuwin and Insuwin forte tablets were evaluated in normal fasted, oral glucose challenged, and diabetes-induced rats. Diabetes mellitus was induced by intraperitoneal administration of streptozotocin (45 mg/kg and nicotinamide 110 mg/kg). Glimepiride (5 mg/ kg orally) was used as standard, Insuwin 194 mg/kg, and Insuwin forte 188 mg/kg test doses were administered for 21 days. After the treatment period, fasting blood glucose levels, serum HbA1c levels, lipid profiles, and biochemical parameters were assessed using standard laboratory techniques. The pancreas histopathology was also carried out. Results:The treatment of Insuwin and Insuwin forte significantly reduces the fasting blood sugar levels in both the normal control and diabetic rats, also Insuwin forte treatment significantly improves the glucose uptake in OGTT, and the abnormal lipid profile like increased total cholesterol, LDL, TG, and decreased HDL in diabetic rats were significantly normalized. Also decreased the elevated serum HbA1c, AST, ALT, and creatinine, additionally Insuwin forte decrease the elevated serum urea in diabetic rats. In histopathology, all the treatments showed better improvement in beta cell regeneration. Conclusion: Based on our results Insuwin and Insuwin forte was effective in diabetes mellitus. In comparison Insuwin forte showed a superior hypoglycemic effect, improve glucose uptake by induced insulin releases, regularize lipid abnormality, better liver and kidney protection, and improve the islet of Langerhans in beta cells. Hence Insuwin forte might be an effective alternative oral hypoglycemic agent for diabetes mellitus.