The Role of Glucagon in Glucose Metabolism in Humans With and Without Bariatric Surgery

Inclusion Criteria: 1. Provision of signed and dated informed consent form from participant. 2. Male or female, ≤65 and ≥18 years old 3. Subjects with history of gastric bypass surgery and sleeve gastrectomy more than a year since surgery and non-surgical subjects without history of gastrointestinal (GI) surgery 4. HbA1c ≤6% 5. Willing to adhere to the study intervention regimen 6. Female subjects of childbearing potential must have a negative pregnancy test at screening and all the study visits, and must not be lactating 7. Females of childbearing potential who are sexually active with a nonsterilized male partner must use at least one highly effective method of contraception from screening and must agree to continue using such precautions during the study.It is strongly recommended for the male partner of a female subject to also use male condom plus spermicide throughout this period. Cessation of contraception after this point should be discussed with a responsible physician. Periodic abstinence, the rhythm method, and the withdrawal method are not acceptable methods of contraception. Exclusion Criteria: 1. Diabetes 2. Pregnancy/lactation 3. Hgb \<11 4. Current GI obstruction or chronic diarrhea 5. Subjects who are not within the age range of 18- 65 years. 6. Evidence of active cardiorespiratory, hepatic, gastrointestinal or renal disease. 7. History of allergy to the administered drugs. 8. History of, or any existing condition that, in the opinion of the investigator, would interfere with evaluation of the investigational product, put the subject at risk, influence the subject's ability to participate or affect the interpretation of the results of the study and/or any subject unable or unwilling to follow study procedures. 9. Substance dependence or history of alcohol abuse and/or excess alcohol intake 10. Patients on ketogenic diet 11. Prisoners or institutionalized individuals 12. AST (SGOT) \> 3 times upper limit of normal 13. ALT (SGPT) \> 3 times upper limit of normal 14. History of clinical hypoglycemia documents based on Whipples' triad (ONLY for Aim 2)