Effects of ultra-processed food reduction intervention on postprandial glucose and glycaemic variability in Korean young adults: study protocol for the ULTRA-CGM randomised controlled trial
- 1Interdisciplinary Program in Precision Public Health, Korea University, Seongbuk-gu, Seoul, Korea (the Republic of)
- 2Department of Health Policy and Management, Korea University, Seongbuk-gu, Korea (the Republic of)
Abstract
Introduction: High intake of ultra-processed foods (UPFs) is associated with an increased risk of type 2 diabetes. However, evidence from randomised controlled trials evaluating the effect of UPF reduction on postprandial glucose responses and glycaemic variability in young adults is limited. The Ultra-Processed Food Reduction Intervention and Continuous Glucose Monitoring (ULTRA-CGM) trial aims to evaluate the effects of a UPF-reducing dietary intervention on postprandial glucose responses and glycaemic variability in healthy Korean young adults.
Methods and analysis: This is a parallel, two-arm randomised controlled trial enrolling 50 participants (aged 20–39 years) with UPF intake ≥25% of daily energy. Following a 10-day baseline monitoring period using CGM and lifestyle diaries, participants are randomised 1:1 to a 40-minute one-on-one UPF-reducing dietary intervention or a 40-minute one-on-one standard dietary counselling based on national dietary guidelines (control). The intervention focuses on reducing UPF consumption, with participants counselled to maintain their usual total energy intake and lifestyle behaviours. After the intervention, participants undergo a 10-day CGM monitoring period and lifestyle diaries. The primary outcome is the change in postprandial glucose responses, quantified as 2-hour incremental area under the curve following meals, from baseline to postintervention. Secondary outcomes include changes in glycaemic variability metrics (coefficient of variation, SD, mean amplitude of glycaemic excursions, glucose spike frequency), time-in-range metrics, body weight, waist circumference, body composition, blood pressure and handgrip strength. For the analyses, between-group differences will be evaluated using analysis of covariance adjusting for baseline values, with daily CGM data analysed using linear mixed-effects models. This trial will provide evidence on whether targeted reduction of UPFs improves postprandial glucose control and glycaemic variability in healthy young adults.
Ethics and dissemination: This study is approved by the Korea University Institutional Review Board (KUIRB-2025-0600-05). It will be conducted in accordance with the principles of the Declaration of Helsinki and the principles of the International Conference on Harmonisation Good Clinical Practice guidelines. Results will be disseminated through publications, academic conferences, PhD dissertation and social and lay media.
Trial registration number: NCT07175701 .
Related
- Investigating the Efficacy of the Proactive Automatised Lifestyle intervention among general hospital patients (ePAL): study protocol of a randomised controlled trial.
- Effectiveness of an Artificial Intelligence Health Education Accurately Linking System (AI-HEALS) for the intervention of chronic kidney disease: a randomised controlled trial protocol
- Common elements-based nurturing care intervention to improve mother-infant responsive interaction and maternal psychological wellbeing in rural Pakistan: findings of a single-blinded individual randomised controlled trial.
- Behavioural intervention and guided stepping training early post-stroke (BIG STEPS): protocol for a multicentre randomised controlled trial.
- Interdisciplinary intervention (GAIN) vs. enhanced usual care for reducing severe post-concussion symptoms in adults 2–4 months post-injury: a stepped wedge cluster randomised controlled trial
BibTeX
@article{kim2026effects,
title = {{Effects of ultra-processed food reduction intervention on postprandial glucose and glycaemic variability in Korean young adults: study protocol for the ULTRA-CGM randomised controlled trial}},
author = {Yujin Kim and Dabin Jeong and Jiyoon Lee and Sooran Yang and Megan S Rojas Guzman and Jihoon You and Jeongsoo Lim and Sujin Lee and Hannah Oh},
journal = {BMJ Open},
year = {2026},
month = oct,
doi = {10.1136/bmjopen-2026-120830},
url = {https://bmjopen.bmj.com/lookup/doi/10.1136/bmjopen-2026-120830},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Effects of ultra-processed food reduction intervention on postprandial glucose and glycaemic variability in Korean young adults: study protocol for the ULTRA-CGM randomised controlled trial
AU - Yujin Kim
AU - Dabin Jeong
AU - Jiyoon Lee
AU - Sooran Yang
AU - Megan S Rojas Guzman
AU - Jihoon You
AU - Jeongsoo Lim
AU - Sujin Lee
AU - Hannah Oh
PY - 2026
DA - 2026/10/06
JO - BMJ Open
DO - 10.1136/bmjopen-2026-120830
UR - https://bmjopen.bmj.com/lookup/doi/10.1136/bmjopen-2026-120830
AB - Introduction: High intake of ultra-processed foods (UPFs) is associated with an increased risk of type 2 diabetes. However, evidence from randomised controlled trials evaluating the effect of UPF reduction on postprandial glucose responses and glycaemic variability in young adults is limited. The Ultra-Processed Food Reduction Intervention and Continuous Glucose Monitoring (ULTRA-CGM) trial aims to evaluate the effects of a UPF-reducing dietary intervention on postprandial glucose responses and glycaemic variability in healthy Korean young adults. Methods and analysis: This is a parallel, two-arm randomised controlled trial enrolling 50 participants (aged 20–39 years) with UPF intake ≥25% of daily energy. Following a 10-day baseline monitoring period using CGM and lifestyle diaries, participants are randomised 1:1 to a 40-minute one-on-one UPF-reducing dietary intervention or a 40-minute one-on-one standard dietary counselling based on national dietary guidelines (control). The intervention focuses on reducing UPF consumption, with participants counselled to maintain their usual total energy intake and lifestyle behaviours. After the intervention, participants undergo a 10-day CGM monitoring period and lifestyle diaries. The primary outcome is the change in postprandial glucose responses, quantified as 2-hour incremental area under the curve following meals, from baseline to postintervention. Secondary outcomes include changes in glycaemic variability metrics (coefficient of variation, SD, mean amplitude of glycaemic excursions, glucose spike frequency), time-in-range metrics, body weight, waist circumference, body composition, blood pressure and handgrip strength. For the analyses, between-group differences will be evaluated using analysis of covariance adjusting for baseline values, with daily CGM data analysed using linear mixed-effects models. This trial will provide evidence on whether targeted reduction of UPFs improves postprandial glucose control and glycaemic variability in healthy young adults. Ethics and dissemination: This study is approved by the Korea University Institutional Review Board (KUIRB-2025-0600-05). It will be conducted in accordance with the principles of the Declaration of Helsinki and the principles of the International Conference on Harmonisation Good Clinical Practice guidelines. Results will be disseminated through publications, academic conferences, PhD dissertation and social and lay media. Trial registration number: NCT07175701 .
SN - 2044-6055
SN - 2044-6055
ER -