Glucagon like peptide -1, or GLP1 is an important, gut derived hormone which has been shown to be involved in insulin secretion, glucose metabolism and glycemic control. Analogs of GLP1 with modification that prolong their half life are currently in use as part of the arsenal of medications that can be deployed in the medical therapy for glucose control in diabetes mellitus. There are currently four GLP1 analogs certified by the FDA and in use in the USA with a fifth scheduled to be included in 2015. Many more are in various stages of development and testing. This paper describes the discovery of the incretin effect attributed to GLP1, the ways in which the incretin effect benefits glucose control and how these effects come about in practice with the currently marketed GLP1 analogs. In addition, GLP1 analog side effects both common and serious are discussed as well potential drug interactions. Finally novel uses of GLP1 are Addressed at the end of this paper