Study of Clinical Response to Acute Metformin By Leveraging Evaluations During a Mixed Meal Tolerance Test for Exploring Glycemia and GeneticS

Inclusion Criteria: * Adult males or non-pregnant females * Age 18-79 * Able and willing to give consent relevant to genetic investigation Exclusion Criteria: * Women who are pregnant, nursing, or at risk of becoming pregnant * Currently taking any medications used for the treatment of diabetes * History of liver disease and/or aspartate aminotransferase (AST) or alanine aminotransferase (ALT) more than 3 times upper limit of normal (ULN) * Estimated glomerular filtration rate (eGFR) \< 60 ml/min/1.73 m2 as calculated by the Modification of Diet in Renal Disease equation * Currently taking or intending to take during the study duration any medication known to affect glycemic parameters, such as glucocorticoids, growth hormone, or fluoroquinolones * Contraindications to safe use of metformin, including planned radiologic or angiographic study requiring contrast within one week of the study completion * Planned changes to any prescribed medications, specifically diuretics, during study enrollment * Participation in any other interventional study during the study duration * Conditions causing intestinal malabsorption, including celiac disease or a history of intestinal or gastric bypass surgery * Dietary restrictions that would prevent consumption of a MMTT * Objection or inability to take metformin