This study is being done to determine the role of a hormone, glucagon-like peptide 1 (GLP-1),
on insulin secretion and to study how GLP-1 works in in diabetic individuals as compared to
non-diabetic individuals, under fasting conditions.
GLP-1 is a naturally occurring hormone made in the intestines. It is released into the
circulating blood after eating and helps to control the blood glucose levels by increasing
insulin secretion by cells in the pancreas. However, the exact method by which GLP-1 causes
insulin secretion and how GLP-1 activity is changed in diabetic persons remain unclear. This
research is being done to address these questions and better understand the function of
GLP-1.
In this research, the investigators will use a synthetic form of Exendin-9 to determine the
effects of GLP-1 on insulin secretion in diabetic and non-diabetic persons. Exendin-9 acts as
a blocker of GLP-1 action, allowing us to study the specific effects of the GLP-1 hormone.
Exendin-9 is an investigational compound, which means it is still being tested in research
studies and is not approved by the U.S. Food and Drug Administration (FDA).
In this study, the investigators will also use the drug Sitagliptin, which is an FDA-approved
drug for the treatment of type 2 diabetes mellitus. In this study, use of Sitagliptin is
considered investigational since it is not being used for treatment of diabetes but is
instead being used to understand how GLP-1 works and to better understand how medications
like Sitagliptin work in patients with type 2 diabetes mellitus.