This is a research study to find out how different people respond to a medication called sitagliptin. Sitagliptin is an FDA approved medication that is used to treat diabetes. We are asking for healthy, non-diabetic volunteers to participate in this 7-week study. If you agree to participate, you will take part in 2 clinic visits that are 4-6 weeks apart. At the clinic visits you will have an oral glucose tolerance test (OGTT) and other blood tests to see how your body processes glucose (sugar). An OGTT is a test in which your drink glucose and then blood samples are taken afterward at specific time points to measure glucose and insulin in your blood. Each clinic visit will last about 5 hours.

Inclusion Criteria:

• • Age: >18 years old

  • Members of Old Order Amish community in Lancaster, PA

Exclusion Criteria:

• • Pregnancy (reproductive age women will undergo pregnancy tests immediately before receiving the drug)

  • Diabetes: HbA1c > 6.5% or fasting plasma glucose >126 mg/dL
  • Estimated glomerular filtration rates (eGFR) <60 mL/min/1.73 m2
  • Anemia: hematocrit < 35%
  • Thyroid status: TSH<0.4 or TSH>5.5
  • ALT or AST in excess of 2X upper limit of normal
  • Drugs that in the physician's judgment would alter response to sitagliptin
  • Significant health issues that in the physician's judgment could increase the risk for participants.

Given that the Amish are a unique founder population, they are more easily identified and at-risk for stigmatization. Therefore, we must consult with the community in order to address this plan to share individual level data.