Insulin therapy is integral to the treatment of diabetes mellitus. Epidemiologic studies have shown its benefits both in terms of improving glycemic control and reducing the risk for long-term diabetic complications for both type 1 and type 2 diabetes. Despite these benefits, barriers to insulin therapy are well documented and include perceived inconvenience, needle anxiety, and portability of device. Historically, patients have often used a vial-and-syringe delivery system to inject a subcutaneous dose of insulin. However, modern regimens provide various choices of delivery systems for prescribers and patients, thus enabling treatment to be tailored to address most patient needs and concerns. Two key alternative delivery systems are now widely available: subcutaneous injection using a pen device, and subcutaneous insulin infusion. In the future inhalations systems for regular human insulin may also become available to patients. Developments in these insulin-delivery systems can improve patients' perceptions of, and experiences with, insulin therapy, potentially reducing barriers to insulin initiation in patients with type 2 diabetes, and also improving aspects of quality of life for those already on an insulin-based regimen.