Personalized Meal Timing and Walking Based on Glucose Patterns in Adults With Prediabetes (CLOCK-PRIME)

CGM-Phenotyped Circadian Glycemic Vulnerability Windows to Personalize Meal Timing and Postprandial Activity in Prediabetes : A Randomized Controlled Trial

This study will test whether glucose sensor data can be used to identify the time of day when adults with prediabetes are most likely to have high blood sugar after meals. Participants will first wear a continuous glucose monitor and wrist activity monitor and record meal times for 10 days. These data will be used to classify each participant's personal "glycemic vulnerability window," such as morning, evening, or generally variable patterns.

Participants will then be randomly assigned to either personalized meal timing plus a short walk after their most vulnerable meal, or to an attention-matched control group receiving sleep hygiene and general step-count advice. The main outcome will be the change in post-meal glucose exposure during each participant's vulnerable window after 4 weeks.

Study Overview

• Status: Recruiting
• Conditions: Prediabetes; Prediabetes (Insulin Resistance, Impaired Glucose Tolerance); Prediabetes or Diabetes
• Intervention / Treatment: Behavioral: Phenotype-Guided Meal Timing and Postprandial Walking; Behavioral: Sleep Hygiene and Step-Count Advice

Detailed Description

Prediabetes is a high-risk metabolic state in which postprandial glucose excursions and glycemic variability may contribute to progression toward type 2 diabetes. Although lifestyle modification can reduce diabetes risk, conventional advice is usually generic and does not account for individual differences in the timing of glucose intolerance across the day. Emerging evidence suggests that circadian biology, meal timing, sleep timing, and postprandial activity may influence glucose regulation, but it remains unclear whether continuous glucose monitoring can be used to personalize the timing of meals and brief activity in adults with prediabetes.

CLOCK-PRIME is a single-center, two-arm, randomized controlled trial in adults with prediabetes. Participants will undergo a 10-day blinded observational run-in period using continuous glucose monitoring, wrist actigraphy, and timestamped meal-photo logging. Run-in data will be used to classify participants into pre-specified circadian glycemic phenotypes based on postprandial glucose incremental area under the curve during morning and evening windows. Participants will be categorized as morning-vulnerable, evening-vulnerable, or globally variable.

After phenotype classification, participants will be randomized to either a phenotype-guided intervention or an attention-matched active control group. The intervention group will receive personalized guidance to shift the highest glycemic-load meal away from the participant's highest-vulnerability window and toward the lowest-vulnerability window. Participants will also be advised to perform a 10-minute brisk walk within 30 minutes after the meal occurring in their highest-vulnerability window. The control group will receive standardized sleep hygiene advice and a general step-count goal, without meal-timing or postprandial walking instructions.

The primary endpoint is the change from baseline to week 4 in vulnerable-window postprandial glucose incremental area under the curve measured by continuous glucose monitoring. Secondary endpoints include time in range, time above range, glucose coefficient of variation, mean postprandial peak glucose, nocturnal mean glucose, sleep regularity, social jetlag, and actigraphy-derived activity patterns. Exploratory mechanistic outcomes include fasting dried-blood-spot measures of cortisol:insulin ratio and selected primary bile acids to assess whether changes in neuroendocrine or enterohepatic metabolic pathways accompany improvement in glycemic vulnerability.

The study is designed to determine whether CGM-derived circadian glycemic vulnerability windows can support a feasible precision lifestyle strategy for reducing postprandial glycemic burden in adults with prediabetes.

• Study Type: Interventional
• Enrollment (Estimated): 105
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Nadia Hussain, MD, PhD; Phone Number: 0505440153; Email: nadia.hussain@aau.ac.ae

Study Locations

• Pakistan
  • Shaikhupura
    • Lahore, Shaikhupura, Pakistan, 50
      • Recruiting
      • Shifa International hospital
      • Contact: Saima T Abass, MD, PhD; Phone Number: 00923206503200; Email: saimaabasstahammal@gmail.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Age 30 to 70 years
• Prediabetes, defined as either:
• HbA1c 5.7% to 6.4% within 3 months of screening, or
• Fasting plasma glucose 100 to 125 mg/dL on two separate occasions
• Body mass index 23 to 40 kg/m²
• Owns a smartphone compatible with study applications
• Willing to wear a continuous glucose monitor and wrist activity monitor during the study period
• Willing to record meals using timestamped meal-photo logging
• Able to provide written informed consent

Exclusion Criteria:

• Current or prior diagnosis of type 1 diabetes or type 2 diabetes
• Use of glucose-lowering medication within the past 3 months
• Use of systemic corticosteroid medication within the past 3 months
• Use of prescription weight-loss medication within the past 3 months
• Current shift work
• Transmeridian travel across more than 2 time zones within 4 weeks before enrollment
• Known untreated or unstable sleep disorder, including obstructive sleep apnea, narcolepsy, or insomnia disorder
• Pregnancy, planned pregnancy, or breastfeeding
• Gastrointestinal disease or surgery likely to affect nutrient absorption
• Current participation in a structured dietary or exercise intervention program
• Estimated glomerular filtration rate less than 60 mL/min/1.73 m²
• Inability or unwillingness to comply with continuous glucose monitoring, wrist actigraphy, meal logging, or study visits

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Phenotype-Guided Meal Timing and Postprandial Walking; Participants will receive personalized lifestyle guidance based on their CGM-derived circadian glycemic vulnerability phenotype. They will be advised to shift their highest glycemic-load meal away from their highest-vulnerability window and toward their lowest-vulnerability window, and to perform a 10-minute brisk walk within 30 minutes after the meal occurring in their highest-vulnerability window.	Behavioral: Phenotype-Guided Meal Timing and Postprandial Walking; Participants randomized to this arm will receive personalized lifestyle guidance based on their CGM-derived circadian glycemic vulnerability phenotype. During the 10-day run-in period, continuous glucose monitoring, wrist actigraphy, and timestamped meal-photo logs will be used to identify the time window in which each participant has the greatest postprandial glucose exposure. Participants will be advised to shift their highest glycemic-load meal away from their highest-vulnerability window and toward their lowest-vulnerability window where feasible. They will also be instructed to perform a 10-minute brisk walk within 30 minutes after the meal occurring in their highest-vulnerability window on at least 5 days per week. The intervention will be delivered through structured dietitian counseling sessions and brief weekly check-in calls. No calorie restriction, prescribed macronutrient diet, or weight-loss target will be imposed.; Other Names: Phenotype-Guided Meal Timing; Postprandial Walking
Active Comparator: Attention-Matched Sleep Hygiene and Step-Count Advice; Participants will receive standardized sleep hygiene advice and general step-count guidance matched for contact time with the intervention group. They will not receive meal-timing advice, carbohydrate-timing advice, or postprandial walking instructions.	Behavioral: Sleep Hygiene and Step-Count Advice; Participants randomized to the active comparator arm will receive standardized sleep hygiene and general physical activity guidance matched for contact time with the intervention arm. Sleep hygiene advice will include maintaining regular sleep and wake times, aiming for adequate sleep duration, and reducing screen exposure before bedtime. Participants will also be advised to increase their average daily step count by approximately 10% above their run-in baseline, with steps distributed freely throughout the day. This arm will not include any advice on meal timing, carbohydrate timing, glycemic vulnerability windows, or postprandial walking. The intervention will be delivered through structured dietitian counseling sessions and brief weekly check-in calls.; Other Names: Sleep Hygiene; Step-Count Advice

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in Vulnerable-Window Postprandial Glucose Incremental Area Under the Curve	Change from baseline run-in period to week 4 in mean postprandial glucose incremental area under the curve during each participant's pre-specified highest glycemic vulnerability window. Postprandial glucose incremental area under the curve will be calculated from continuous glucose monitoring data over 120 minutes after logged meals using the trapezoidal rule.	Baseline run-in period to Week 4, unit of measure: mg/dL·min

Collaborators and Investigators

• Sponsor: Shifa International Hospital

Study record dates

Study Major Dates

• Study Start (Estimated): June 1, 2026
• Primary Completion (Estimated): June 30, 2026
• Study Completion (Estimated): July 15, 2026

Study Registration Dates

• First Submitted: May 24, 2026
• First Submitted That Met QC Criteria: May 24, 2026
• First Posted (Actual): June 1, 2026

Study Record Updates

• Last Update Posted (Actual): June 1, 2026
• Last Update Submitted That Met QC Criteria: May 24, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Keywords: Prediabetes; Continuous Glucose Monitoring; Glycemic Variability; Meal Timing; Precision Lifestyle Medicine
• Additional Relevant MeSH Terms: Endocrine System Diseases; Metabolic Diseases; Glucose Metabolism Disorders; Hyperinsulinism; Hyperglycemia; Nutritional and Metabolic Diseases; Diabetes Mellitus; Insulin Resistance; Prediabetic State; Glucose Intolerance
• Other Study ID Numbers: SH-34988909; SIAC-02392 (Other Grant/Funding Number: Shifa Hospital Research Council grant)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: De-identified individual participant data underlying the published results may be shared upon reasonable request after publication, subject to institutional approval, data-use agreement, and protection of participant confidentiality.

Drug and device information, study documents

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