Diabetes mellitus is a metabolic disorder associated with short term as well as long-term undesirable complications caused by persistent hyperglycemia. Recently, there has been emerging evidence that natural foods and their bioactive compounds are the key contributors to the treatment of diabetes and associated complications. This study was designed to explore the therapeutic efficacy of a fish protein-rich diet for managing diabetes and associated complications in the diabetic Wistar rat model. A high-protein (HP) diet (45% and 55% fish protein rich in ω3 fatty acids) was given to alloxan-induced diabetic rats for 28 days. Blood samples were collected for monitoring serum glucose, oxidative stress markers, lipid profile, kidney function markers, serum proteins, and liver function markers. Results indicated that there was a noteworthy control (p < .05) of serum glucose, oxidative stress, and lipid profile in HP diet treated diabetic rats. Treatment with 45% and 55% fish diet appreciably improved the concentration of serum creatinine, urea, uric acid and exhibited a vibrant improvement in renal functions. Our results confirmed that the HP diet restored total protein and albumin concentration in blood. The HP diet treatment also restored the normal serum aspartate transaminase and alanine aminotransferase concentration.