The rationale for combining GLP-1 receptor agonists with basal insulin.

• Type 2 diabetes mellitus (T2DM) is progressive; the more intensively it is treated, the greater is the risk of hypoglycaemia and weight gain. Achieving treatment intensification while mitigating these risks presents a challenge to patient management. • Basal insulins provide control of fasting glucose; however, their utility in the control of postprandial glucose excursions is limited. • Glucagon-like peptide-1 (GLP-1) receptor agonists stimulate glucose-medicated insulin secretion, suppress glucagon secretion, delay gastric emptying and decrease appetite. Use of GLP-1 receptor agonists in combination therapy with basal insulin offers an alternative approach to intensification of insulin therapy. • Prospective interventional trials demonstrate that GLP-1 receptor agonists added to basal insulin decrease postprandial glucose levels, lower HbA1c levels, decrease weight and lower basal insulin requirements without increasing the risk of major hypoglycaemic events. • The current clinical data are limited by the lack of any data on the long-term effects of GLP-1 receptor agonists over additional prandial regimens; they may be beneficial or deleterious. • Although cost, gastrointestinal side effects and long-term safety should be taken into account when considering this combination, it appears to be growing in popularity and is likely to be an important therapeutic option for T2DM in the future.