Diabetes mellitus (DM) is indeed considered a metabolic disease-causing chronic complication in several organs. The present study aimed to investigate the Long-Term Complications in diabetic dogs. This study was performed on 50 chronic diabetic dogs (age: 6-14 years) compared to 20 control healthy dogs. Clinically, affected dogs showed polydipsia, polyuria, polyphagia, eye cataract and emaciation. There was highly significant decrease in RBCs, Hb, PCV, and lymphocyte levels, however, a significant increase in WBCs, neutrophil, and platelet levels in diabetic dogs. Biochemically, diabetic dogs showed a significant increase in random blood glucose, HbA1C, kidney marker (SDMA), cardiac markers (Troponin T and CK-MB), and a significant decrease in immunoglobulins (IgG, IgM, IgA). Electrocardiographic examination showed abnormal T-waves (wide and enlarged) and cardiac arrhythmia, Ultrasonographic and radiographic examinations showed pancreatitis, fatty liver, nephritis, and emphysematous cystitis, in conclusion, this study revealed that diabetes mellitus in dogs lead to chronic complications affecting organs including the eye, the liver, the kidney, and the heart. Therefore, it is recommended to monitor and manage chronic diabetic dogs to control these complications.