The investigators recently demonstrated that blockade of Glucagon-Like Peptide-1's (GLP-1) receptor (GLP1R) results in changes in islet function without changes in circulating GLP-1. These effects are more pronounced in people with early type 2 diabetes (T2DM) in keeping with increased expression of PC-1/3 and GLP-1 that is observed in diabetic islets. However, its regulation is at present unknown. There is evidence that α-cell proglucagon processing is subject to paracrine regulation by the β-cell3. It is unclear if the effects of GLP1R agonism on islet GLP-1 differ in Type 1 diabetes (T1DM) compared to T2DM. This experiment will examine the effect of glycemic control ± a GLP1R agonist on islet GLP-1 in people with (T2DM) and without (T1DM) β-cells.