Abstract
Insulin deficiency, often aggravated by insulin resistance, results in type 2 diabetes mellitus (T2DM). With the availability of glucagon-like peptide 1 receptor agonists and sodium-glucose cotransporter 2 inhibitors, basal insulin (BI) therapy is no longer the first-line option after lifestyle modification plus oral agents is insufficient. In contrast to BI, the newer medications require minor titration, lower hyperglycemia in a glucose-dependent manner, and reduce body weight. Importantly, the newer agents reduce cardiorenal events in the short term. Nonetheless, insulin therapy continues to play a key role in control of hyperglycemia and therefore long-term prevention of vascular complications. Its use is essential in many circumstances, including metabolic emergencies, new diabetes onset, latent autoimmune diabetes (LADA), pregnancy, and when other agents are less desirable due to comorbidities. BI is needed in the frequent condition of failure of other therapies to keep HbA1c to target and/or intolerance of them. There are several advantages to the combination of BI with the newer medications given their different but complementary mechanisms of action, primarily, the lower dose of each, improving adherence and outcomes while decreasing the side effects. Multiple choices for single or combination use can better meet the variety of clinical phenotypes in the heterogeneous T2DM population, using the tenets of precision medicine.