The document discusses various types of oral hypoglycemic agents (OHAs) used to treat type 2 diabetes mellitus (T2DM). It describes the classifications of OHAs including biguanides like metformin, sulphonylureas, meglitinides, thiazolidinediones, and others. For each class, it provides details on mechanisms of action, pharmacokinetics, dosing, side effects, and contraindications. Metformin and sulphonylureas have been used the longest and remain first-line treatment options, though each class has advantages and disadvantages discussed in the document.