After Dinner Rest a While, After Supper Walk a Mile? A Systematic Review with Meta-analysis on the Acute Postprandial Glycemic Response to Exercise Before and After Meal Ingestion in Healthy Subjects and Patients with Impaired Glucose Tolerance

Effects of postprandial exercise timing on blood glucose and fluctuations in patients with type 2 diabetes mellitus

BACKGROUND

The aim of this study was to assess how moderate-intensity aerobic exercise performed 45 minutes and 90 minutes after a meal affects blood glucose levels and fluctuations in individuals diagnosed with type 2 diabetes mellitus (T2DM).

METHODS

Twenty-two patients with T2DM, who were solely receiving oral hypoglycemic medication, were enrolled and divided randomly into two categories: those exercising 45 minutes after a meal (45-minute postprandial exercise group) and those exercising 90 minutes post-meal (90-minute postprandial exercise group). Both groups engaged in a 30-minute session of moderate-intensity aerobic stationary bike exercise following breakfast. This aerobic exercise regimen consisted of two stages, with the groups switching exercise timings after the initial phase. Continuous glucose monitoring (CGM) was utilized to evaluate the blood glucose levels and fluctuations in the participants.

RESULTS

After breakfast, both overall daily blood glucose levels and the area under the curve for blood glucose following breakfast were reduced in the 45-minute postprandial exercise group compared to the 90-minute postprandial exercise group. The 45-minute postprandial exercise group demonstrated greater time spent within the target glucose range and less time above the target range than the 90-minute postprandial exercise group. Additionally, measures such as standard deviation, mean amplitude of glycemic excursions, largest amplitude of glycemic excursions, and postprandial glucose excursion for breakfast, peak postprandial glucose levels, and duration of elevated glucose levels were all lower in the 45-minute postprandial exercise group compared to the 90-minute postprandial exercise group.

CONCLUSIONS

Moderate-intensity aerobic exercise lasting 45 minutes after meals was found to be more efficient in decreasing blood glucose levels and minimizing fluctuations compared to exercising 90 minutes after meals in patients with T2DM. Additionally, it notably reduced the peak in blood glucose levels after meals.

One minute of light-intensity stair-stepping decreases postprandial glycaemia in the evening in non-diabetic adults: A randomized controlled trial

Prior studies have investigated the efficacy of a single 1 min bout of stair-stepping on reducing postprandial blood glucose (BG) in the morning, but none have investigated this effect in the evening when glycaemic responses are larger due to circadian regulation and β-cell responsiveness. This work investigated the efficacy of a 1 min bout of self-selected, low-intensity stair-stepping performed in the evening on reducing the change from baseline to the 60 min time point postprandial BG. Thirty people (43% male, 29 (10) years) participated in a randomized crossover-controlled trial. Participants completed two separate evening trials following an oral glucose tolerance test (OGTT) (75 g of dextrose dissolved in water): (a) 0 min of stair-stepping seated control condition, and (b) 1 min of stair-stepping condition. One minute of stair-stepping attenuated the change from baseline to 60 min postprandial BG versus control condition (2.5 (2.8) vs. 4.3 (2.3) mmol/L (P < 0.001). Area under the curve (AUC) and incremental area under the curve (iAUC) were lower for the 1 min condition versus control (mean difference = -0.4,95% CI: 0.1-0.8 (P = 0.023) and (mean difference = -0.6, 95% CI 0.1-1.1 mmol/L-1 min-1 (P = 0.043), respectively. The modified BORG rate of perceived exertion scale showed participants perceived the exercise as light intensity (1.9 (1.1)). A single, 1 min bout of low-intensity stair stepping at a self-selected pace reduced evening postprandial BG levels following an OGTT in young non-diabetic adults.

Diet, physical activity, and sleep in relation to postprandial glucose responses under free-living conditions: an intensive longitudinal observational study

BACKGROUND

It remains unclear what lifestyle behaviors are optimal for controlling postprandial glucose responses under real-world circumstances in persons without diabetes. We aimed to assess associations of diet, physical activity, and sleep with postprandial glucose responses in Asian adults without diabetes under free-living conditions.

METHODS

We conducted an observational study collecting intensive longitudinal data using smartphone-based ecological momentary assessments, accelerometers, and continuous glucose monitors over nine free-living days in Singaporean men and women aged 21-69 years without diabetes. The outcome was the 2-h postprandial glucose incremental area under the curve (mmol/l*min). Associations were estimated using linear mixed-effect models.

RESULTS

The analyses included 11,333 meals in 789 participants. Greater variations in glucose and lifestyle measures were observed within individuals than between individuals. Higher consumption of carbohydrate-rich and deep-fried foods and lower consumption of protein-rich foods were significantly associated with higher postprandial glucose levels (incremental area under the curve). The strongest association was observed for including refined grains (46.2 [95% CI: 40.3, 52.1]) in meals. Longer postprandial light-intensity physical activity (-24.7 [(-39.5, -9.9] per h) and moderate-to-vigorous-intensity physical activity (-58.0 [-73.8, -42.3]) were associated with substantially lower postprandial glucose levels. Longer daily light-intensity physical activity (-7.5 [-10.7, -4.2]) and sleep duration (-2.7 [-4.4, -1.0]) were also associated with lower postprandial glucose levels. Furthermore, postprandial glucose levels were the lowest in the morning and the highest in the afternoon. The results were largely consistent for males and females and for participants with and without prediabetes.

CONCLUSIONS

Consuming less refined grains and more protein-rich foods, getting more physical activity (particularly during the postprandial period), and having a longer sleep duration were associated with lower postprandial glucose levels in Asian adults without diabetes. Our findings support multi-component lifestyle modifications for postprandial glucose control and highlight the importance of the timing of eating and physical activity.

Barriers and system improvements for physical activity promotion after gestational diabetes: A qualitative exploration of the views of healthcare professionals

AIM

Physical activity is an important behaviour for managing the ten times increased risk of type 2 diabetes after gestational diabetes. Previous studies exploring physical activity promotion in healthcare focus on general practitioners but have not explored the gestational diabetes pathway. Therefore, this paper explores the barriers to and suggestions for, activity promotion along the gestational diabetes healthcare pathway.

METHODS

The paper was written in accordance with the Standards for Reporting Qualitative Research. Patient and Public Involvement with women who had lived experiences of gestational diabetes informed purposeful sampling by identifying which healthcare professional roles should be targeted in participant recruitment. Participants were recruited through word-of-mouth, that is, email and connections with local healthcare service leads. Twelve participants took part in semi-structured one-to-one interviews, analysed using reflexive thematic analysis.

RESULTS

Participants included a Public Health Midwife (n = 1), Diabetes Midwifes (n = 3), Diabetes Dietitian (n = 1), Diabetes Consultants (n = 2), Diabetes Specialist Nurse (n = 1), general practitioners (n = 2), Practice nurse (n = 1) and a Dietitian from the UK National Diabetes Prevention Program (n = 1). Six themes were generated: 'management of gestational diabetes takes precedent', 'poor continuity of care', 'lack of capacity to promote PA', 'beliefs about the acceptability of PA promotion', 'resources to support conversations about PA' and 'adapting healthcare services for women post-gestational diabetes'.

CONCLUSIONS

During pregnancy messaging around physical activity is consistent, yet this is specific for managing gestational diabetes and is not followed through postnatally. Improvements in continuity of care are necessary, in addition to ensuring the availability and links with wider exercise and activity schemes.

Effects of light-intensity physical activity on cardiometabolic parameters in young adults with overweight and obesity: The SED-ACT randomized controlled crossover trial

AIMS

To investigate how a change in body position with light-intensity physical activity (PA) 'snacks' (LIPAS, alternate sitting and standing, walking or standing continuously) compared with uninterrupted prolonged sitting affects glucose metabolism and heart rate variability (HRV) parameters in young adults with overweight and obesity.

MATERIALS AND METHODS

We conducted a four-arm randomized controlled crossover trial. The following conditions were tested during an 8-h simulated workday: uninterrupted prolonged sitting (SIT), alternate sitting and standing (SIT-STAND; 2.5 h total), continuous standing (STAND), and continuous walking (1.0 mph; WALK). The primary outcome was to investigate how a change in body position (alternate sitting and standing, walking or standing continuously) compared with uninterrupted sitting affects mean 8-h glucose metabolism. Secondary outcomes included the effects on 2-h postprandial glucose concentrations, as well as on 8-h/24-h heart rate and HRV parameters, in the respective study arms. Capillary blood samples were drawn from an hyperemised earlobe in the fasted state and once every hour during each trial intervention by puncturing the earlobe with a lancet and collecting 20 μL of blood (Biosen S-Line Lab+; EKF diagnostics, Barleben, Germany). HRV was assessed for 24 h including the 8-h intervention phase, and a home phase by means of a Holter electrocardiogram. All participants received the same standardized non-relativised breakfast and lunch during the four trial visits.

RESULTS

Seventeen individuals (eight women, mean age 23.4 ± 3.3 years, body mass index 29.7 ± 3.8 kg/m2, glycated haemoglobin level 34.8 ± 3.1 mmol/mol [5.4 ± 0.3%], body fat 31.8 ± 8.2%) completed all four trial arms. Compared with SIT (89.4 ± 6.8 mg/dL), 8-h mean glucose was lower in all other conditions (p < 0.05) and this was statistically significant compared with WALK (86.3 ± 5.2 mg/dL; p = 0.034). Two-hour postprandial glucose after breakfast was approximately 7% lower for WALK compared with SIT (p = 0.002). Furthermore, significant time × condition effects on HRV parameters favouring light-intensity walking were observed (p < 0.001).

CONCLUSIONS

Replacement and interruption of prolonged sitting with light-intensity walking showed a significant blood glucose-lowering effect and improved HRV during an 8-h work environment in young adults with overweight and obesity.

Interventions to improve glycaemic control in people living with, and at risk of developing type 2 diabetes

Type 2 diabetes mellitus is one of the most prevalent health conditions worldwide, affecting millions of individuals and posing significant public health challenges. Understanding the nature of type 2 diabetes, its causes, symptoms and treatments is crucial for managing and preventing its complications. Many different dietary strategies are used by individuals to treat and manage diabetes. This review provides an overview of popular dietary strategies that have evidence for improving long-term glycaemic control or achieving diabetes remission, as well as strategies that may be useful to reduce postprandial hyperglycaemia, which may be of use in the prevention of diabetes, but also as strategies for those already diagnosed but trying to manage their condition better. Recent clinical trials have provided evidence that in people living with type 2 diabetes who also live with overweight or obesity, using a total diet replacement weight loss programme results in significant and substantial weight loss, and as a result, many people can achieve remission from their diabetes. There has been considerable interest in whether similar effects can be achieved without reliance on formula foods, using real diet approaches. Reduced or low-carbohydrate diet approaches hold some promise, with observational or preliminary findings suggesting beneficial effects, but evidence from robust trials or systematic reviews of randomized controlled trials is still lacking. The Mediterranean dietary pattern, low in saturated fat and high in monounsaturated fat, also has some potential, with evidence to suggest some people can lose weight and achieve remission using this approach, which may be easier to adhere to longer term than more intensive total diet replacement and low-carbohydrate strategies. Plant-based diets that advocate for the elimination of animal-based and/or animal-derived foods have increased in popularity. There is evidence from epidemiological studies that people who follow these diets have a lower risk of developing type 2 diabetes, and evidence from trials and systematic reviews of trials that changing to a dietary pattern lower in animal-based and animal-derived foods has benefits on glycaemic control and other markers of cardiovascular disease. While these approaches all provide food or nutrient prescriptions, approaches that incorporate periods of fasting do not provide rules on the types of foods that can or cannot be consumed, but rather provide time windows of when to eat. Evidence suggests that these approaches can be as effective in achieving energy restriction and weight loss as approaches that advocate continuous energy restriction, and there is evidence for benefits on glycaemic control independent of weight loss. Finally, popular dietary strategies that may be useful to use or combine to help prevent postprandial hyperglycaemia include reducing the glycaemic index or glycaemic load of the diet, high-fibre diets, eating foods in a meal in the order vegetables > protein > carbohydrates, preloading or combining acids such as vinegar or lemon juice with meals and engaging in low-intensity aerobic exercise immediately after meals.

At-home bodyweight interval exercise in the fed versus fasted state lowers postprandial glycemia and appetite perceptions in females

Limited research has characterized the metabolic health benefits of bodyweight interval exercise (BWE) performed outside of a laboratory setting. Metabolic responses to exercise can also be influenced by meal timing around exercise, but the interactive effects of BWE and nutrition are unknown. This study investigated the effects of BWE performed in the fasted or fed state on postprandial glycemia, post-exercise fat oxidation and appetite perceptions. Twelve females (23 ± 2 years; 22 ± 2 kg/m2) underwent two virtually-monitored trials that involved completing BWE (10 × 1 min, 1 min recovery) 5 min before (FastEX) or beginning BWE 10 min after (FedEX) a standardized breakfast. Heart rate and rating of perceived exertion (RPE) were measured during exercise and capillary glucose concentrations were measured for 2 h postprandial. Following exercise, appetite perceptions were assessed and Lumen expired carbon dioxide percentage (L%CO2) was measured as an index of fat oxidation. Heart rate (85 ± 5%) and RPE (14 ± 2) did not differ between conditions (p > 0.05). Postprandial glucose mean (6.1 ± 0.6 vs. 6.8 ± 0.8 mmol/L, p = 0.03), peak (7.4 ± 1.2 vs. 8.5 ± 1.5 mmol/L, p = 0.01), and area under the curve (AUC) (758 ± 72 vs. 973 ± 82 mmol/L × 2 h, p = 0.004) were lower in FedEX versus FastEX. Appetite perceptions were lower in FedEX versus FastEX (-87.63 ± 58.51 vs. -42.06 ± 34.96 mm, p = 0.029). Post-exercise L%CO2 was transiently decreased 30 min post-exercise in both conditions (4.03 ± 0.38 vs. 4.29 ± 0.34%, p = 0.0023), reflective of increased fat oxidation following BWE. These findings demonstrate that BWE performed in the fed compared to the fasted state lowered postprandial glycemia and appetite perceptions in females.

Interactive effects of low-volume interval exercise and nutrition on glycemic control

Low-volume interval training has been demonstrated to improve indices of 24 h glycemic control using continuous glucose monitoring in individuals with or at risk for metabolic diseases. Nonetheless, there are inconsistencies in the literature with respect to the effects of interval exercise on 24 h glycemia, which may partly result from different nutritional conditions and/or controls adopted across various studies. This current opinion aims to provide a concise overview of the effects of acute and chronic interval exercise on 24 h glycemic control, while also describing how nutrition can influence and modify these responses. Given the distinct impact of dietary intake on blood glucose regulation, the adoption of diverse dietary control strategies during measurement of 24 h glycemia-spanning from using the participant's habitual diet to providing standardized meals customized to individual energy requirements-may contribute to varying conclusions across studies regarding the influence of interval exercise on 24 h glycemia. In addition, nutritional manipulations surrounding exercise, including whether interval exercise commences in the fasted or fed state, the macronutrient composition of post-exercise meals, and the presence of an energy and/or carbohydrate deficit among participants, offer important context when considering the effects of interval exercise on 24 h glycemia. Additional well-controlled studies are warranted to explore the interactive effects of interval exercise and nutrition on 24 h glycemia. These efforts will assist in refining exercise and nutrition recommendations aimed at improving glycemic control.

Exercise Prescription for Postprandial Glycemic Management

The detrimental impacts of postprandial hyperglycemia on health are a critical concern, and exercise is recognized a pivotal tool in enhancing glycemic control after a meal. However, current exercise recommendations for managing postprandial glucose levels remain fairly broad and require deeper clarification. This review examines the existing literature aiming to offer a comprehensive guide for exercise prescription to optimize postprandial glycemic management. Specifically, it considers various exercise parameters (i.e., exercise timing, type, intensity, volume, pattern) for crafting exercise prescriptions. Findings predominantly indicate that moderate-intensity exercise initiated shortly after meals may substantially improve glucose response to a meal in healthy individuals and those with type 2 diabetes. Moreover, incorporating short activity breaks throughout the exercise session may provide additional benefits for reducing glucose response.

Post-meal exercise under ecological conditions improves post-prandial glucose levels but not 24-hour glucose control

We investigated whether post-meal walking (PMW) improved post-prandial glucose and 24h glucose control under free-living conditions among physically inactive young women.

METHODS

Young women (Age: 20±1years; percent body fat: 28.2 ± 12%; BMI: 23.8 ± 4.2kg·m-1) completed a randomised crossover study to assess if PMW confers benefit. On the PMW day, women completed three bouts of brisk walks, and on the Control day they were instructed to follow normal habitual activities. Continuous glucose monitors captured post-prandial and 24h glucose, and physical activity monitors tracked physical activity throughout the study.

RESULTS

PMW walking increased total daily step count (Control = 9,159 ± 2,962 steps vs. PMW = 14,611±3,891 steps, p<0.001) and activity scores (Control=33.87±1.16 METs·h vs. PMW = 36.11±1.58 METs·h, p < 0.001). PMW led to lower 3h average post-prandial glucose (main effect of condition, p=0.011) and 3h post-prandial area under curve glucose responses (main effect of condition, p = 0.027) compared to the control condition. Post hoc analysis revealed the largest decline occurred after dinner (3h average glucose Control = 7.55±1.21 mmol/L vs. PMW = 6.71 ± 0.80mmol/L, p = 0.039), when insulin sensitivity is typically diminished. Despite improvements in post-prandial glucose control, this did not translate to improvements in 24h glucose control (p > 0.05).

CONCLUSION

Physically inactive and metabolically healthy young women, PMW improves post-prandial glucose but not 24h glucose control.

The effect of preprandial versus postprandial physical activity on glycaemia: Meta-analysis of human intervention studies

This meta-analysis aims to investigate the effect of preprandial physical activity (PA) versus postprandial PA on glycaemia in human intervention studies. Medline and Embase.com were searched until February 2023 for intervention studies in adults, directly comparing preprandial PA versus postprandial PA on glycaemia. Studies were screened using ASReview (34,837) and full texts were read by two independent reviewers (42 full text, 28 included). Results were analysed using pooled mean differences in random-effects models. Studies were either acute response studies (n = 21) or Randomized Controlled Trials (RCTs) over multiple weeks (n = 7). In acute response studies, postprandial outcomes followed the expected physiological patterns, and outcomes measured over 24 h showed no significant differences. For the RCTs, glucose area under the curve during a glucose tolerance test was slightly, but not significantly lower in preprandial PA vs postprandial PA (-0.29 [95 %CI:-0.66, 0.08] mmol/L, I2 = 64.36 %). Subgroup analyses (quality, health status, etc.) did not significantly change the outcomes. In conclusion, we found no differences between preprandial PA versus postprandial PA on glycaemia both after one PA bout as well as after multiple weeks of PA. The studies were of low to moderate quality of evidence as assessed by GRADE, showed contradictive results, included no long-term studies and used various designs and populations. We therefore need better RCTs, with more similar designs, in larger populations and longer follow-up periods (≥12 weeks) to have a final answer on the questions eat first, then exercise, or the reverse?

Exercise Prescription Principles among Physicians and Physical Therapists for Patients with Impaired Glucose Control: A Cross-Sectional Study

Exercise confers a multitude of benefits with limited adverse side effects, making it a powerful "medication" for a plethora of diseases. In people living with uncontrolled glucose levels, exercise can be an effective "medication" to assist in the management of hyperglycemia. We sought to survey healthcare providers (physicians and physical therapists) to determine the current state of exercise recommendation for people with glucose control issues. Healthcare providers were surveyed from six academic medical centers in the Midwest to determine the recommended exercise parameters (type, frequency, duration, intensity, and timing) for patients with glucose control issues. Data from 209 practitioners who completed the survey were used for analysis. Chi-square tests were used to determine differences in exercise recommendations between physical therapists (PTs) and physicians (MD/DOs). PTs and MD/DOs recommended similar exercise parameters. Of all respondents, 78.9% recommended exercise to patients with glucose control issues. Respondents who considered themselves to be active exercisers were more likely to recommend exercise than those who were not exercisers. Only 6.1% of all respondents recommended post-meal exercise. Healthcare providers overwhelmingly recommended exercise for people with glucose control issues, but the "timing" is not congruent with best practice recommendations.