Do glucagon-like peptide-1 receptor (GLP-1R) agonists have potential as adjuncts in the treatment of type 1 diabetes?

INTRODUCTION: Glucagon-like peptide-1 (GLP-1) is produced by the gut, stimulates insulin secretion from the pancreatic β-cells, and inhibits glucagon secretion from the α-cells. The GLP-1 receptor (GLP-1R) agonists are used in the treatment of type 2 diabetes (T2DM). AREAS COVERED: This review covers the clinical trials of the GLP-1R agonists (exenatide and liraglutide) and their potential as adjunct treatment in type 1 diabetes mellitus (T1DM). EXPERT OPINION: GLP-1R agonists are unable to increase insulin secretion, in subjects with T1DM, who are C-peptide negative. Also, the GLP-1R agonists either have no effect or cause a small inhibition of glucagon secretion in subjects with T1DM. There is no evidence that the GLP-1R agonists cause a major reduction in HbA1c, or have a major effect on hypo- or hyperglycemia in subjects with TD1M. The main beneficial effect of the GLP-1R agonists is probably the modest weight loss, which may underlie the reduction in dose of insulin used. Given that the GLP-1R agonists cause gastrointestinal adverse effects, and with reduced insulin doses, increase the risk of ketosis, it seems to me that the risk with these agents may outweigh any benefit in T1DM, and that they have little potential as adjuncts in the treatment of T1DM.