Ultrasound-assisted extraction of curcumin from Curcuma longa was performed in an ultrasonic bath at 30°C using ethanol for 40 min. A successful attempt has been made to prepare curcumin–zinc (Zn) complex using a simple chemical procedure. The complex formation and its stoichiometry were characterized using elemental analysis, Fourier transform (FT)-IR and UV spectroscopy which revealed the interaction of Zn(II) ion (M) with curcumin (ligand, L) to proceed via (ML) complex type formation. Oral administration of curcumin–Zn complex at a concentration of 150 mg/kg body weight/rat/d for 45 d in streptozotocin-induced diabetic rats in comparison to curcumin and/or Zn administration exerted a hypoglycemic effect. A significant reduction in blood glucose, glycosylated hemoglobin (Hb)A1c, and lipid profile parameters with an excellent improvement in plasma insulin levels have been attained. Also, the reduced activities of serum aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea, and creatinine in the diabetic rats treated with the complex exhibited the non-toxic nature of the curcumin–Zn complex. Finally, the larger extent of the complex in hyperglycemic improvement in comparison to curcumin and/or Zn supplementation was interpreted by its dual action on glucose and insulin maintenance.