Xiaoyuan Zhang

1. Globally, disorders of glucose and lipid metabolism represent the eighth leading cause of death and disability, with sedentary behaviour (SB) identified as a critical factor contributing to thes...

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Background: The role of carbohydrate intake in glycemic control remains debated, whether the proportion of energy from carbohydrates or the consistency of daily intake matters more. This study investigated the associations between carbohydrate intake and dynamic glucose metrics in overweight and obese adults using continuous glucose monitoring (CGM), with a focus on distinguishing within-person from between-person effects. Methods: This observational study recruited 99 sedentary, overweight or obese adults (mean age 25.55 years, mean body mass index (BMI) 30.04 kg/m²). Dietary intake was recorded using food diaries, and interstitial glucose was monitored continuously for 7–14 days using the CGM system. Physical activity was measured with accelerometers. Multivariable linear regression models were used to examine associations between carbohydrate energy ratio and glucose parameters. Additionally, linear mixed-effects models with person-mean centering were applied to disentangle within-person and between-person effects of carbohydrate intake, controlling for age, gender, BMI, moderate-to-vigorous physical activity (MVPA), and total caloric intake.Results: The carbohydrate energy ratio was not associated with mean glucose but was significantly associated with increased glycaemic variability. However, daily within-person fluctuations in carbohydrate intake predicted higher glycemic variability (standard deviation (SD): β = 0.38, p < 0.0001; coefficient of variation (CV): β = 6.16, p 0.05).Conclusion: Carbohydrate intake proportion does not influence mean glucose levels but specifically exacerbates glucose fluctuations. Critically, day-to-day consistency of carbohydrate intake—rather than the long-term average level—is a key determinant of glycemic stability. Dietary strategies for overweight/obese adults should prioritize maintaining stable daily carbohydrate intake and controlling total energy, rather than merely reducing the carbohydrate percentage.

Aims: Emerging evidence suggests that glycemic variability may be relevant to metabolic health, even in people without diabetes. This study aims to assess the effects of exercise on 24‐h continuous glucose profiles in the non‐diabetic population. Materials and Methods: Adhering to PRISMA guidelines, PubMed, Web of Science, Embase, and CNKI databases were searched up to August 25, 2025. The meta‐analysis was performed on the 24‐h mean blood glucose (MBG), mean amplitude of glycemic excursion (MAGE), peak blood glucose (MAX), 4–6‐h incremental area under the glucose curve (iAUC), and time in range (TIR). Risk of bias was assessed using RoB2 and ROBINS‐I V2. Subgroup analyses considered population, age, study design, and exercise type. Results: Twenty‐three studies (18 RCTs, five non‐RCTs; 408 participants) were included. Exercise significantly reduced MBG (weighted mean difference [WMD] = −0.17 mmol/L), MAGE (WMD = −0.27 mmol/L), MAX (WMD = −0.63 mmol/L), and 4–6‐h iAUC (standardized mean difference [SMD] = −0.60), while increasing TIR (WMD = 6.22%), compared to non‐exercise or usual activity controls. Other outcomes showed no significant changes. Subgroup analyses indicated that age influenced MBG, while population and exercise type affected MAGE. Risk of bias showed 38.9% RCTs as low risk, 61.1% RCTs with some concerns, and all non‐RCTs at moderate risk. Conclusions: Acute exercise produced minor, parameter‐specific improvements in certain CGM metrics (MBG, MAGE, MAX, TIR, and 4–6‐h iAUC). These modest changes indicate subtle physiological adaptations. Larger, longer, and better‐controlled trials are needed to determine their clinical relevance.

Recent advancements in Continuous Glucose Monitoring (CGM) technology provide a novel solution for monitoring dynamic glucose fluctuations during endurance exercise, enabling personalized carbohydrate refueling strategies. However, direct evidence demonstrating its superiority over traditional refueling guidelines has been lacking. This exploratory study compared a CGM-informed protocol with a traditional interval-based (TRAD) carbohydrate refueling protocol on endurance exercise responses. Twelve healthy, non-diabetic males (age = 32.3 ± 6.3 years) participated in two trials involving 75 minutes of continuous cycling at 50% peak power output, with the two carbohydrate refueling protocols implemented in a randomized, crossover order. In the TRAD protocol, participants received standard carbohydrate solutions at regular 15-min intervals, while replenishment timing in the CGM-informed protocol was guided by real-time glucose trends, particularly during declines. No significant differences were observed in heart rate, blood lactate, or perceived exertion between conditions (all p > 0.05). However, CGM-informed protocol displayed a lower coefficient of variation of glucose levels (8.82 ± 4.68%) than the TRAD protocol (11.95 ± 3.41%, Cohen's d = 0.76, p = 0.013), indicating a steadier blood glucose trend. The mean 75-minute interstitial glucose total area under the curve was significantly lower for the CGM-informed protocol (423.4 ± 39.1 mmol·min·L-1), compared to the TRAD protocol (448.6 ± 38.2 mmol·min·L-1, Cohen's d = 0.65, p = 0.008). While the CGM-informed protocol did not demonstrate beneficial effects on physiological responses over the TRAD protocol, it may aid in stabilizing glucose levels during prolonged endurance exercise. Further research is warranted to explore the applications of personalized carbohydrate refueling strategy based on CGM technology on athletic performance across various exercise protocols. .

Introduction: Exercise, a non-pharmacological intervention, is widely recognized for its beneficial effects on metabolic health. However, the different effects of morning and afternoon exercise on various metabolic indicators remain unclear. Therefore, this study aimed to systematically evaluate and analyze the effect of exercise at various times on body composition, glucose metabolism, and lipid metabolism. Methods: Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, this study conducted a literature search in electronic databases including PubMed, Embase, and Web of Science. The studies included exercise regimens in the morning, afternoon, or morning and evening and analyzed body weight, body mass index, fat mass, fasting blood glucose, hemoglobin A1c (HbA1c), insulin, or triglycerides. The risk of bias was assessed using the Cochrane tool (Rob2), and publication bias was assessed using funnel plots and Egger tests. Results: Thirteen long-term and five acute studies were analyzed (n = 658 participants). Morning training was more effective in reducing body fat (mean deviation [MD] -0.39, 95% confidence interval [CI] -0.66 to -0.13, ), waist circumference (MD -0.53, 95% CI -1.06 to -0.00, I² = 31%, p = 0.05), and HbA1c (MD -0.11, 95% CI -0.19 to -0.03, I² = 0%, p = 0.009), whereas afternoon training was better in lowering fasting blood glucose (MD 0.13, 95% CI 0.01 to 0.24, I² = 0%, p = 0.03) and triglycerides (MD 0.1, 95% CI 0.02 to 0.18, I²= 41%, p = 0.02). Conclusion: Both morning and afternoon training are beneficial for metabolic health; however, their effects differ. Morning training was more likely to reduce body fat, waist circumference, and HbA1c, whereas afternoon exercise was more likely to reduce fasting blood glucose and triglycerides. Incorporating exercise timing into clinical guidelines could enhance the effectiveness of lifestyle interventions for metabolic disorders.

Context Recent studies suggest that light-intensity physical activity may enhance cardiometabolic health and reduce mortality risk in adults. However, more information is required to understand the patterns of light-intensity physical activity and postprandial cardiometabolic health. Objective This study examined the effects of different light-intensity walking patterns on postprandial cardiometabolic responses in young obese adults. Design A randomized crossover trial was conducted. Setting The study was conducted in the laboratory. Participants The study analyzed baseline (fasting) and 6-hour postprandial concentrations of glucose, insulin, triglycerides, and blood pressure (BP) in 16 young obese adults. Interventions Participants underwent four 7-hour experimental conditions with a 7–20-day washout period: uninterrupted sitting (SIT), 30-minute light-intensity walking (EX+SIT), 3-minute light-intensity walking every 30 minutes (BR), and 30-minute light-intensity walking with 3-minute light-intensity walking every 30 minutes (EX+BR). Main Outcome Measures Incremental areas under the curve (iAUC) for each outcome and average BP were compared between SIT and walking conditions. Results Compared with SIT, all walking conditions reduced iAUCs for glucose and average diastolic BP (all pp0.05). Conclusions All patterns of light-intensity walking reduced postprandial glucose concentrations and diastolic BP in young obese adults, suggesting benefits for glycemic control. Continuous 30-minute light-intensity walking alone, or combined with brief 3-min bouts also attenuated postprandial insulin concentrations, highlighting light-intensity walking as a promising strategy for improving cardiometabolic health in young obese adults.