Role of Alpha-to-beta Cell Communication to Adapt Insulin Secretion to Insulin Resistance.

Aim 2A: Inclusion Criteria: * Age 18-45 * Body Mass Index (BMI) \< 27.0 * Fasting plasma glucose of ≤ 95 mg/dL or HbA1c value ≤ 5.8% as measured at screening visit Exclusion Criteria: * Active medical disease: e.g. active infectious, inflammatory, neurodegenerative or mental health disorders * Personal history of diabetes or pancreatitis * Personal history of cardiac, gastrointestinal, renal or liver disease * Immediate family history of diabetes * Renal insufficiency (eGFR \< 60 mL/kg/min) * Anemia (hematocrit \< 34%) as measured at screening visit * Pregnant females * Poor vein access * Consumption of daily medications that alter glucose metabolism of GI function (glucocorticoids, psychotropics, narcotics, metoclopramide) * Apparent sensitivity to the study peptide as determined by the skin test Aim 2B: Inclusion Criteria: * Age 35-60 * Body Mass Index (BMI) ≥ 27.0 * Fasting plasma glucose of \< 126 mg/dL or HbA1c value \< 6.5% as measured at screening visit Exclusion Criteria: * Active medical disease: e.g. active infectious, inflammatory, neurodegenerative or mental health disorders * Personal history of diabetes or pancreatitis * Personal history of cardiac, gastrointestinal, renal or liver disease * Immediate family history of diabetes * Renal insufficiency (eGFR \< 60 mL/kg/min) * AST and/or ALT levels \> 3x the upper limit of the normal range * Anemia (hematocrit \< 34%) as measured at screening visit * Pregnant females * Poor vein access * Consumption of daily medications that alter glucose metabolism of GI function (glucocorticoids, psychotropics, narcotics, metoclopramide) * Apparent sensitivity to the study peptide as determined by the skin test