Diabetes mellitus is a chronic metabolic disorder characterized by impaired insulin secretion and pancreatic β-cell dysfunction. The search for therapeutic strategies that promote β-cell regeneration remains a key focus in diabetes research. This study investigated the potential regenerative effects of glibenclamide, catechin, and Azadirachta indica (neem) leaf extract on pancreatic β-cells in alloxan-induced diabetic rats. Experimental diabetes was induced using alloxan monohydrate, followed by oral administration of the test agents for a defined treatment period. Biochemical parameters, including fasting blood glucose and serum insulin levels, were measured, alongside histological examination of pancreatic tissues. Results revealed that glibenclamide, catechin, and A. indica extract significantly reduced blood glucose and improved insulin secretion compared with untreated diabetic controls. Histopathological analysis indicated notable restoration of β-cell morphology and islet integrity, with A. indica extract and catechin demonstrating synergistic potential comparable to glibenclamide. These findings suggest that catechin and A. indica leaf extract possess promising anti-diabetic and β-cell regenerative properties, offering potential as complementary therapeutic agents in the management of diabetes mellitus.