Insulin therapy is an effective method for reducing blood glucose levels in patients with type 2 diabetes mellitus (T2DM), and most patients with T2DM eventually require insulin replacement to attain and preserve satisfactory glycaemic control. All patients with T2DM should be considered as potential candidates for intensive insulin treatment; however, there are certain considerations regarding replacement therapy for different types of people and special populations, such as patients with multiple comorbidities, adolescents, pregnant women and the elderly. Lowering HbA1c levels in isolation without assessing the patient as a whole is becoming redundant. HbA1c targets should be individualized to the specific patient, and insulin treatment ought to be customized accordingly. There are several questions that need to be taken into account when considering adding insulin therapy to other oral antidiabetic agents, for example, for whom and when insulin therapy is indicated and which basal insulin should be utilized. Potential barriers exist related to patients, providers and health-care systems that can delay the start of insulin therapy, and every effort should be made to identify and address these obstacles.