Rationale for a titratable fixed-ratio co-formulation of a basal insulin analog and a glucagon-like peptide 1 receptor agonist in patients with type 2 diabetes

Objective: Achieving and maintaining recommended glycemic targets, including those for glycated hemoglobin A1c (A1C), is key to improving outcomes in patients with type 2 diabetes (T2D). As fasting plasma glucose and postprandial glucose contribute to overall A1C, targeting both is essential for sustaining glycemic control. Methods: This review examines the complementary mechanisms of action of glucagon-like peptide 1 (GLP-1) receptor agonists and basal insulin; they both enhance glucose-stimulated insulin release and suppress glucagon secretion. GLP-1 receptor agonists also slow gastric emptying and increase satiety. Results: Adding a GLP-1 receptor agonist to therapy with a basal insulin analog has been associated with improved overall glycemic control, with comparable risk of hypoglycemia and no weight gain. Titratable fixed-ratio co-formulations of basal insulin and a GLP-1 receptor agonist have been shown to improve glycemic control, with less complex dosing schedules, possibly increasing treatment adherence. The slow titration of fixed-ratio co-formulations has been shown to reduce the occurrence and severity of gastrointestinal adverse events associated with the use of a separate GLP-1 receptor agonist. Titratable fixed-ratio co-formulations also mitigate insulin-associated weight gain, and show a comparable risk of hypoglycemia to basal insulin use alone. Conclusions: The efficacy and safety of titratable fixed-ratio co-formulations have been demonstrated for insulin degludec/liraglutide and insulin glargine/lixisenatide in the DUAL and LixiLan trials, respectively, in both insulin-naive and -experienced patients. Titratable fixed-ratio co-formulations represent an attractive treatment option for many patients with T2D.