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NCT Number: NCT06813014

Pharmacogenetics of Response to Sitagliptin (PRS)

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.

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Key information

Conditions

Diabetes Diabetes Mellitus Endocrine System Diseases Glucose Metabolism Disorders Metabolic Diseases Nutritional and Metabolic Diseases

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

University of Maryland Amish Research Clinic

Lancaster, Pennsylvania, 17602, United States

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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.

Treatment and study plan

Oral Glucose Tolerance Test

Procedure

Three hour glucose tolerance test

Primary outcomes

  1. Sitagliptin-induced enhancement of early insulin secretion

    Time frame: 6 weeks

    This represents the incretinomimetic effect of sitagliptin, which contributes importantly to the mechanism whereby DPP4is decrease HbA1c in T2D patients. Because histograms for sitagliptin-induced increase in our index of early insulin secretion (T30:T60) demonstrated a skewed distribution, we will apply a logarithmic transformation of data which yields a normal distribution. Thus, the drug effect is defined as: log(T30:T60 ins)sita - log(T30:T60 ins)control.

  2. Sitagliptin-induced change in glucose tolerance

    Time frame: 6 weeks

    Sitagliptin-induced change in glucose tolerance. This is a consequence of enhanced insulin secretion, which reflects most closely the desired effect of the drug to decrease plasma glucose and decrease HbA1c. Because histograms for sitagliptin-induced increase in our index of glucose tolerance (T30:T60) demonstrated a skewed distribution, we will apply a logarithmic transformation of data which yields a normal distribution. Thus, the drug effect is defined as: log(T30:T60 gluc)sita - log(T30:T60 gluc)control.

Secondary outcomes

  1. Area under the curve for insulin concentration

    Time frame: 6 weeks

    Area under the curve of insulin concentration measured from oral glucose tolerance test using trapezoidal rule

  2. Area under the curve for glucose concentration

    Time frame: 6 weeks

    Area under the curve for glucose concentration measured from the oral glucose tolerance test using the trapezoidal rule

  3. Area under the curve for intact GIP

    Time frame: 6 weeks

    Area under the curve for levels of intact GIP during the first hour of the OGTT as calculated by the trapezoidal rule

  4. Area under the curve for intact GLP1

    Time frame: 6 weeks

    Area under the curve for levels of intact GLP1 during the first hour of the OGTT as calculated by the trapezoidal rule

  5. Area under the curve for C-peptide levels

    Time frame: 6 weeks

    Area under the curve for C-peptide levels as a direct index of insulin secretion

Other outcomes

  1. Parameters of a mathematical model (insulin secretion and glucose sensitivity of the β-cell

    Time frame: 6 weeks

    We will apply mathematical modeling to the oral glucose tolerance test data it assess measures of insulin secretion and glucose sensitivity of the β-cell

Study contacts

Contact information is provided by the study sponsor or research team.

Amber L Beitelshees

CONTACT

[email protected]

14107060118

Kamah Woelfel

CONTACT

[email protected]

Sponsors and collaborators

Lead sponsor

University of Maryland, Baltimore

Other

Registry information

Official study title

Sitagliptin's Effects on Glucose-stimulated Insulin Secretion and Oral Glucose

Acronym: PRS

Important dates

Study start
2026
Primary completion
2031
Study completion
2032
First posted
Feb 6, 2025
Registry last updated
Feb 18, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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