Glycemic Effects of Meals - Repeatability Trial With Continuous Glucose Monitoring (GEM-RT CGM)

Almost half of adults in the United States have either diabetes mellitus (DM) or prediabetes (preDM), but many are undiagnosed and unaware of their condition. Current DM diagnosis and risk prediction are based on single "snapshot" measurements including: fasting blood glucose, postprandial glucose, and hemoglobin (Hb)A1c. Continuous glucose monitoring (CGM) offers a dynamic view of glucose levels throughout the day which enables characterizing individuals' dynamic glycemic profiles in response to physiological and environmental stimuli better than the conventional point-in-time glucose quantification approaches. By analyzing glycemic patterns from CGM tracings, it may be possible to identify individuals at increased risk of developing diabetes. However, an important prerequisite is to establish the reliability and consistency of glucose response patterns captured by CGM under controlled conditions.

Participants will be given six different meals to examine the glucose responses to these meals. Two of these meals (white rice and an Ensure drink) will be given twice for each participant to investigate whether individuals have the same glucose response to the same meal given on different days. Glucose will be measured using continuous glucose monitors, that have a thin wire sensor that measures glucose under the skin every five minutes for up to 10 days.

Study Overview

• Status: Not yet recruiting
• Conditions: Glucose Response
• Intervention / Treatment: Other: Six meal challenges

Detailed Description

This is a pilot study in which each participant undergoes six meal challenges (one each morning) under free-living conditions, while wearing a blinded CGM sensor. Glucose levels will be continuously measured, and meal challenge sequence will be randomly assigned to each participant.

The study objectives are to:

1. determine the within meal replicability of postprandial glucose response to a Ensure and White Rice meal challenges
2. evaluate if a whole food meal challenge (White Rice) exhibits lower reliability and greater physiological variability (under the chewing vs. not chewing condition) in postprandial glucose response compared to a standardized liquid mixed meal tolerance test (Ensure)
3. compare the postprandial average peak glucose response and 4 hour incremental area under the curve (iAUC) for the Ensure tolerance test, mountain dew tolerance test, White Rice, and typical breakfast.

These findings will inform the design of future studies and the potential use of CGM-based dietary challenges for early detection of metabolic risk.

• Study Type: Interventional
• Enrollment (Estimated): 20
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Nicole L Spartano, PhD; Phone Number: 315-415-2040; Email: spartano@bu.edu
• Study Contact Backup: Name: Bahar Bakshi, MS; Phone Number: (315) 415-2040; Email: baharb@bu.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Generally healthy
• English speaking

Exclusion Criteria:

• Prior diagnosis of diabetes or taking medications that influence glucose metabolism, such as insulin, glucocorticoids, or Glucagon-like peptide-1 (GLP-1) receptor agonists.
• Taking hydroxyurea medication
• Taking beyond the maximum dose of acetaminophen (4g/day)
• Known food allergies or severe sensitivities to any study materials (dairy or soy)
• Limited and non-readers
• Cognitive impairment

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm

Intervention / Treatment

Experimental: Continuous glucose monitoring; Each participant will have a Dexcom G6 CGM sensor applied to the upper arm. The order of the six study meals will be randomly assigned.

Other: Six meal challenges; Two of the meal challenges will only be provided once: (1) a 20oz bottle of Mountain Dew (2) a "typical breakfast" that participants would eat normally. The other four challenges consist of two meal events that will each be repeated: (1) two 8-ounce bottles of Ensure® nutritional shake (2) one cup of microwaved white rice (microwaveable Minute brand Jasmine Rice cups). The rice challenge will be performed once with normal chewing and once by swallowing without chewing, while the Ensure challenge will be repeated the same way on both days.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Glycemic patterns from CGM	Beginning at baseline, a 4-hour incremental area under the glucose curve (iAUC) will be calculated using the trapezoidal method. Peak glucose will be defined as the maximum glucose excursion within the 4-hour window. Continuous glucose monitoring (CGM) CGM values are recorded every 5 minutes, so linear interpolation will be used to provide a CGM value every minute to line up with the ingestion time documented in the participant's log.	baseline, every 4 hours for 6 days

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Fasting blood glucose levels	This outcome will be assessed from the CGM data recorded after a10 hour fast.	baseline, daily for 6 days
Post prandial glucose levels	This outcome will be assessed from the CGM data recorded daily 4 hours after a study meal.	baseline, daily for 6 days

Collaborators and Investigators

• Sponsor: Boston University
• Investigators: Principal Investigator: Nicole L Spartano, PhD, BUCA School of Medicine, Endocrinology, Diabetes, Nutrition and Weight Management

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: September 18, 2025
• First Submitted That Met QC Criteria: December 8, 2025
• First Posted (Actual): December 19, 2025

Study Record Updates

• Last Update Posted (Actual): April 28, 2026
• Last Update Submitted That Met QC Criteria: April 27, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Metabolic risk; Fasting blood glucose; Continuous glucose monitoring (CGM); Post prandial glucose; Hemoglobin (Hb)A1c; CGM-based dietary challenges
• Other Study ID Numbers: H-46249

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No