NCT06223555 · National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Variability In Mixed Meal Tests: Fixed Versus Adjusted to Energy Needs Caloric Dose
What this study is about
Background: Researchers use mixed meal tolerance tests (MMTTs) to look at how people s bodies respond to eating a meal. However, researchers do not agree on how to decide the number of calories to give in each meal. Some use fixed meals, which are the same size for everyone, and some use adjusted meals, based on the size of the person s body.
View original scientific description
Background: Researchers use mixed meal tolerance tests (MMTTs) to look at how people s bodies respond to eating a meal. However, researchers do not agree on how to decide the number of calories to give in each meal. Some use fixed meals, which are the same size for everyone, and some use adjusted meals, based on the size of the person s body. Researchers want to know which MMTT is best to use for future research. Objective: To learn how fixed vs adjusted meals affect blood glucose levels in healthy people. Eligibility: Healthy people aged 18 years or older. Design: Participants will have 3 or 4 clinic visits of up to 8 hours in 8 weeks. Participants will have baseline tests: Their height, weight, and waist size will be measured. They will have an oral glucose tolerance test: A needle attached to a tube (IV) will be inserted into a vein in the arm. They will have a sugary drink. Blood samples will be taken from the tube at intervals up to 3 hours after the drink. They will have a body scan. Participants will have 2 MMTT visits. One will include a fixed meal and one will include an adjusted meal. They will have tests at both visits: Resting metabolic rate: A clear hood will be placed over the participant s head while they rest for 20 minutes. This will measure the oxygen they breathe in and out. MMTT. Participants will have 5 minutes to drink a liquid meal. Blood samples will be taken at intervals for the next 4 hours....
Interventions
OTHER
Fixed Mixed Meal Test
a FIXED dose meal that will be 900 kcal of a liquid meal
OTHER
Adjusted Mixed Meal Test
a body weight ADJUSTED dose liquid meal. (30% of total daily energy requirements)
Primary outcome measures
To determine whether an adjusted energy dose MMTTor a fixed dosed meal will result in greater variability in glucose area under the curve (AUC) within the same participants across a range of BMIs.
Time frame: Baseline, Visit 3/4
Glucose AUC associated with MMTT conditions (fixed vs. adjusted).
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- In order to be eligible to participate in this study, an individual must meet all of the following criteria:
- Provision of signed and dated informed consent form.
- Agreement to adhere to Lifestyle Considerations throughout study duration.
- Males and females; Age \>= 18years
- Healthy, as determined by medical history, physical examination, and laboratory tests.
Exclusion criteria
- An individual who meets any of the following criteria will be excluded from participation in this study:
- Current use of medications, dietary supplements, or alternative therapies known to alter energy metabolism.
- Fasting plasma glucose \>= 126 mg/dL
- Type I or Type II Diabetes Mellitus by self-report.
- Hematologic disorders including significant anemia (male hemoglobin \< 13.0 g/dL or female hemoglobin \< 11.0 g/dL)
- Current pregnancy, pregnancy within the past 6 months or currently lactating
- History or self-report of gastrointestinal disease, including inflammatory bowel diseases (e.g. Chron s disease and ulcerative colitis), malabsorption syndromes (e.g. celiac disease), gastric ulcer (active) which may alter metabolism or absorption of study food by self-report
- Evidence of alcohol abuse as defined by an 8-point score on the Alcohol consumption screening AUDIT questionnaire in adults.
- Participants who report taking large doses of acetaminophen (\> 3 grams daily) who cannot stop acetaminophen 24 hours prior to and following the meal tests will be excluded from the study.
- Inability to consume provided food based on a food allergy or intolerance.
- Conditions not specifically mentioned above may serve as criteria for exclusion at the discretion of the investigators.
- Any disorder, unwillingness, or inability not covered by any other exclusion criteria which, in the investigator s and/or team s opinion, jeopardizes the safety of the participant or others or would interfere with adherence to the protocol (such as claustrophobia). Conditions not specifically mentioned above may serve as criteria for exclusion at the discretion of the investigators.
Where
- Phoenix, Arizona
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jun 12, 2026 · Source of record for eligibility and locations