Diabetes mellitus is a chronic condition characterized by insufficient insulin production or ineffective insulin utilization, resulting in elevated blood glucose levels. This review outlines the various types of diabetes, including type 1, type 2, and gestational diabetes, and their potential complications, such as cardiovascular diseases, neuropathy, and nephropathy. It explores the mechanisms of action and examples of common anti-diabetic medications, including biguanides, sulfonylureas, meglitinides, thiazolidinediones, alpha-glucosidase inhibitors, DPP-4 inhibitors, and SGLT2 inhibitors. The review further details the evaluation methods for anti-diabetic activity, encompassing both in-vitro assays, such as 𝛼-amylase and 𝛼-glucosidase inhibition assays, and in-vivo models, like streptozotocin-induced and high-fat diet-induced diabetes in rodents. These methodologies are crucial for assessing insulin sensitivity, glucose metabolism, and other diabetes-related markers, providing insights into the efficacy and safety of potential anti-diabetic therapies.