Insulin is a major protein hormone secreted by the β-cells of the pancreas and is important for the control of diabetes. Insulin is usually administered to diabetic patients through subcutaneous injection. This mode of therapy has certain inherent disadvantages such as local pain, itching and insulin lipodystrophy around the injection site. Hence, pharmaceutical scientists have been trying to design an oral delivery system for insulin. Many challenges are associated with the oral delivery of insulin, relating to the physical and chemical stability of the hormone, and its absorption and metabolism in the human body. Here we discuss various strategies for the oral delivery of insulin that are being tried out, as well as methods used to improve the absorption of orally consumed insulin and to reduce its degradation by digestive enzymes.