Insulin is the most the effective available medication for treating hyperglycemia in type 2 diabetes. If used appropriately, it can decrease any level of elevated A1C to, or close to, the desired goal. This chapter begins with a presentation of indications for insulin therapy in type 2 diabetes. Normal physiological insulin patterns will be reviewed, highlighting how awareness of these patterns can guide the development of insulin treatment regimens. The next section will provide an overview of the characteristics of available insulin preparations. The chapter will end with a discussion of potential strategies for initiating and advancing insulin therapy.