Preclinical and Clinical Data on Extraglycemic Effects of GLP-1 Receptor Agonists.
The diverse actions of the incretin hormone glucagon-like peptide (GLP)-1 include insulinotropic, beta-cell preservative, cardioprotective and vasodilatory effects. This spectrum makes GLP-1 an appealing therapeutic option for patients with type 2 diabetes. However, its rapid metabolism by the enzyme dipeptidyl peptidase (DPP)-4 renders it impractical. Incretin-based analogues have been developed to extend endogenous GLP-1 action (GLP-1 receptor agonists) and to hamper its degradation (DPP-4 inhibitors). Evidence suggests that GLP-1 receptor agonists and DPP-4 inhibitors have different pharmacodynamic and pharmacokinetic effects. For example, GLP-1 receptor agonists deliver supraphysiologic levels of GLP-1 analogues designed to resist inactivation by DPP-4, whereas DPP-4 inhibition conserves native GLP-1 resulting in concentrations within the physiologic range. Furthermore, GLP-1 receptor agonists induce glucose-dependent insulin secretion, beta-cell protection, and other extraglycemic benefits such as weight loss and improvement in markers of cardiovascular risk. In contrast, DPP-4 inhibitors are weight neutral and have modest effects on glucose control. DPP-4 inhibition is dependent on the availability of endogenous GLP-1, which appears to be adversely affected by type 2 diabetes and its progression. Therefore, DPP-4 inhibitors may be better suited for patients with mild hyperglycemia without comorbidities. This review examines the present understanding of the pancreatic effects of endogenous GLP-1, and the extrapancreatic actions it exerts on human bodily systems. Also, it analyzes available preclinical and clinical data on incretin therapies with respect to glycemia, lipids, blood pressure, and weight.
Gallwitz
Baptist
B
Department of Medicine IV, Universitätsklinikum Tübingen, Otfried-Müller-Str. 10, 72076 Tübingen, Germany.