Chronotype and chrononutrition, both are emerging research fields in nutritional epidemiology. However, its association with glycemic control in the global population is less clear. A better understanding of how activity/ eating time can influence glucose levels in prediabetic individuals may improve strategies for blood glucose control. The present paper aims to determine the associations of chronotype and chrononutrition with glucose tolerance among prediabetic individuals in Malaysia.

This is a prospective longitudinal study named Chrono-DMTM, that targets to recruit 166 newly diagnosed prediabetic individuals from the community clinics in Malacca, Malaysia. Respondents will be followed-up for 6 months: (1) baseline (1st oral glucose tolerance test (OGTT)); (2) second visit (at 3rd month); and (3) third visit (2nd OGTT at 6th month). Data collection includes sociodemographic and anthropometry measurements (weight, height, body fat, visceral fat, waist and hip circumference). Dietary intake and meal timing are collected using the 3-day dietary record while data on sleep pattern, light exposure, chronotype and chrononutrition will be collected using validated questionnaires. Physical activity will be captured using a validated IPAQ questionnaire and pedometer during periods of wearing Continuous glucose monitoring (CGM) sensor. CGM, fasting plasma glucose (FBG), OGTT and HbA1c are performed to assess glycemic outcomes.

Inclusion Criteria:

1. Newly diagnosed prediabetic individuals who have been first seen by clinical dieticians registered under the Ministry of Health Malaysia.
2. Malaysian ≥ 18 years old.
3. Those who plan to continue prediabetes care at the selected community clinic in Melaka.
4. Those who can read, write and understand the Malay Language.

Exclusion Criteria:

1. Night shift workers at least 3 times per week.
2. Known sleep disorder.
3. Pregnant Women.
4. Those on oral glucose-lowering medications, diabetes supplements, anticonvulsant medications or oral steroids currently or in the last month.
5. Those with prior explored to any information regarding time-of-eating/time-of-activity restriction.
6. Those with chronic kidney disease. They are excluded as current research lack of evidence to support the accuracy of using 24-hour continuous glucose monitoring system (CGMS) (Freestyle Libre Pro, Abbott, Germany).

The proposed study will be conducted in community clinics in Malacca, Malaysia. Malacca is the capital of the coastal stage, located in southwestern Malaysia, with an estimated total population of 0.93 million in the year 2019 (Department of Survey and Mapping Malaysia, 2021). In 2019, National Health and Morbidity Survey reported that 17% of Malaccan adults had hyperglycemia and 13.7% of them had known diabetes. Malacca is 1 out of the top five states showing the highest prevalence of diabetes in Malaysia (IPH, NIH and MOH, 2019). Prediabetes and diabetes will be defined according to the latest Clinical Practice Guideline in Malaysia (WHO & IDF, 2006; ADA, 2020; MOH et al., 2020).

The validation and reliability of Chrononutrition Profile Questionnaire planned to share with researchers but the other data are not shared with other researchers.