Immediate post-breakfast physical activity improves interstitial postprandial glycemia: a comparison of different activity-meal timings

Effects of electrical stimulation of the lower extremities on postprandial hyperglycemia and arterial stiffness

PURPOSE

To compare the acute effects of electrical stimulation (ES) of the lower extremities on postprandial hyperglycemia and arterial stiffness during oral glucose tolerance testing (OGTT).

METHODS

In a randomized crossover study, eight healthy young men completed three experimental trials in which they underwent ES for 30 min, starting 60 min before (Before) or 30 min after (After) ingesting 75 g of glucose; ES was not performed in the control trial (Control). The subjects' blood glucose levels and brachial-ankle pulse wave velocity (baPWV) were measured as an index of arterial stiffness at baseline and 30, 60, and 120 min after glucose ingestion. Serum insulin levels were measured at baseline and 60 min after glucose ingestion.

RESULTS

The subjects' glucose intake led to an increase in their blood glucose concentration in all trials, however, in the After trial, ES resulted in significantly lower blood glucose concentrations at 60 min post glucose ingestion compared to the Control and Before trials. The area under the curve (AUC) of serum insulin concentrations during the OGTT in the After trial was significantly lower than that in the other two trials. Moreover, glucose ingestion did not increase the baPWV, however, 30 min of ES during the postprandial state acutely reduced the baPWV.

CONCLUSION

These results suggest that ES is most effective in reducing postprandial hyperglycemia when administered after a meal. Thus, lower extremity ES may be an alternative exercise method to activate postprandial glucose metabolism in healthy individuals.

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.

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?

The effect of bodyweight exercise on 24-h glycemic responses determined by continuous glucose monitoring in healthy inactive adults: a randomized crossover study

Vigorous intermittent exercise can improve indices of glycemia in the 24 h postexercise period in apparently healthy individuals. We examined the effect of a single session of bodyweight exercise (BWE) on glycemic responses using continuous glucose monitoring (CGM) under controlled dietary conditions. Healthy inactive adults (n = 27; 8 males, 19 females; age: 23 ± 3 years) completed 2 virtually supervised trials spaced ~ 1 week apart in a randomized, crossover manner. The trials involved an 11-min BWE protocol that consisted of 5 × 1-min bouts performed at a self-selected pace interspersed with 1-min active recovery periods or a non-exercise sitting control period (CON). Mean heart rate during the BWE protocol was 147 ± 14 beats per min (75% of age-predicted maximum). Mean 24 h glucose after BWE and CON was not different (5.0 ± 0.4 vs 5.0 ± 0.5 mM respectively; p = 0.39). There were also no differences between conditions for measures of glycemic variability or the postprandial glucose responses after ingestion of a 75 g glucose drink or lunch, dinner, and breakfast meals. This study demonstrates the feasibility of conducting a remotely supervised BWE intervention using CGM under free-living conditions. Future studies should investigate the effect of repeated sessions of BWE training or responses in people with impaired glycemic control.

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

BACKGROUND

The most effective way to cope with high blood sugar spikes is to engage in physical activity in temporal proximity to food intake. However, so far, it is unclear as to whether there is an optimal time for physical activity around food intake.

OBJECTIVES

We aimed to identify the impact of pre- and post-meal exercise on postprandial glucose excursions in humans with and without type 2 diabetes mellitus.

METHODS

We conducted a systematic review with meta-analysis, PROSPERO registration number: CRD42022324070. We screened MEDLINE/PubMed, Cochrane/CINAHL/EMBASE, and Web of Knowledge until 1 May, 2022. We used the risk of bias rating with the crossover extension of the Cochrane risk of bias assessment tool II. Standardized mean differences (SMDs, Hedges' g) with 95% confidence intervals (CIs) were calculated as pooled effect estimates of a random-effects meta-analysis. Eligibility criteria included three-armed randomized controlled trials comparing the acute effects of pre- and post-meal exercise to a no-exercise control in humans.

RESULTS

Eight randomized controlled trials (crossover trials, high risk of bias) with 30 interventions in 116 participants (47 diagnosed with type 2 diabetes, 69 without type 2 diabetes) were eligible. Exercise after meal ingestion (real food or meal replacement drinks) led to a reduction in postprandial glucose excursions compared with exercise before eating (15 effect sizes; SMD = 0.47 [95% CI 0.23, 0.70]) and an inactive control condition (15 effect sizes; SMD = 0.55 [95% CI 0.34, 0.75]. Pre-meal exercise did not lead to significantly lower postprandial glucose compared to an inactive control (15 effect sizes; SMD =  - 0.13 [95% CI - 0.42, 0.17]). The time between meal and exercise (estimate =  - 0.0151; standard error = 0.00473; Z =  - 3.19; p = 0.001; 95% CI - 0.024, - 0.006) had a moderating influence on postprandial glucose excursions.

CONCLUSIONS

Exercise, i.e., walking, has a greater acute beneficial impact on postprandial hyperglycemia when undertaken as soon as possible after a meal rather than after a longer interval or before eating.

CLINICAL TRIAL REGISTRATION

The review was pre-registered in the PROSPERO database (CRD42022324070). The date of submission was 07.04.2022, with the registration on 08.05.2022.

Metabolically Healthy Obesity: Are Interventions Useful?

PURPOSE OF REVIEW

This review aims to detail the current global research state of metabolically healthy obesogenesis with regard to metabolic factors, disease prevalence, comparisons to unhealthy obesity, and targeted interventions to reverse or delay progression from metabolically healthy to unhealthy obesity.

RECENT FINDINGS

As a long-term condition with increased risk of cardiovascular, metabolic, and all-cause mortality risks, obesity threatens public health on a national level. The recent discovery of metabolically healthy obesity (MHO), a transitional condition during which obese persons carry comparatively lower health risks, has added to confusion about the true effect of visceral fat and subsequent long-term health risks. In this context, the evaluation of fat loss interventions, such as bariatric surgery, lifestyle changes (diet/exercise), and hormonal therapies require re-evaluation in light of evidence that progression to high-risk stages of obesity relies on metabolic status and that strategies to protect the metabolism may be useful in the prevention of metabolically unhealthy obesity. Typical calorie-based exercise and diet interventions have failed to reduce the prevalence of unhealthy obesity. Holistic lifestyle, psychological, hormonal, and pharmacological interventions for MHO, on the other hand, may at least prevent progression to metabolically unhealthy obesity.

Metabolic responses to acute sprint interval exercise training performed after an oral 75-gram glucose load in individuals with overweight/obesity

There is evidence supporting that acute sprint interval training (SIT) might improve metabolic responses to postprandial glucose, but results are inconclusive. The aim of the present study was to explore the effects of acute SIT on metabolic response and substrate utilization in individuals with overweight/obesity after an oral 75-gram glucose challenge. Thirty-three participants with overweight/ obesity (32.7 ± 8.3 years, 24 male, 9 female) participated in the study and a crossover design was followed. After the 75-gram glucose load, participants were randomly allocated to two groups: no exercise (resting) or SIT protocol. Metabolic data including respiratory quotient (RQ) and substrate utilization rates (fats and carbohydrates) were collected using the COSMED Q-NRG + ® calorimeter. The RQ was significantly lower in the acute SIT group (0.76 [0.01]; p < 0.0001) than in the resting group (0.80 [0.01]; p = 0.036) at the 120-min postprandial time point, and the RQ area under the curve (AUC) was also lower in the SIT group (mean difference of -6.62, 95% CI -12.00 to -1.24; p = 0.0161). The contribution of fat to energy expenditure increased after SIT during the postprandial period whereas the contribution of carbohydrates decreased. The AUC for fat contribution was significantly higher (mean difference 2311.9, 95% confidence interval [CI] 578.8 to 4043.3; p = 0.0098) and the AUC for carbohydrate contribution was significantly lower (mean difference -2283.1, 95% CI -4040.2 to -527.1; p = 0.0117) in the SIT group than in the resting group. In conclusions, acute SIT might have a positive effect on metabolic responses to postprandial glucose and, accordingly, should be recommended for improving metabolism in people with overweight/obesity.

Walking Attenuates Postprandial Glycemic Response: What Else Can We Do without Leaving Home or the Office?

We evaluated the effects of different exercise types suitable for a home/work setting on the postprandial glucose response. Twenty-three healthy, active, young individuals performed one of two studies (12 in Study 1 and 11 in Study 2), with four randomized protocols each. After a meal high in carbohydrate content (1 g of carbohydrate per kg of body weight), in Study 1, participants performed 30 min of either walking (WALK), bench stepping exercise (STEP) or isometric wall squat (SQUAT); in Study 2, participants performed 30 min of either walking (WALK), neuromuscular electrical stimulation alone (P_NMES) or superimposed on voluntary muscle contraction (VC_NMES). In both studies, participants performed a prolonged sitting condition (CON) that was compared to the exercise sessions. In Study 1, WALK and STEP significantly reduced the glucose peak compared to CON (p < 0.011). In Study 2, the peak was significantly reduced in WALK compared to CON, P_NMES and VC_NMES (p < 0.011) and in VC_NMES compared to CON and P_NMES (p < 0.011). A significant reduction of 3 h glucose iAUC was found for WALK and VC_NMES compared to CON and P_NMES (p < 0.033). In conclusion, WALK is the most effective strategy for improving the postprandial glycemic response. However, STEP and VC_NMES can also be used for reducing postprandial glycemia.

Continuous Glucose Monitoring and Physical Activity

Continuous glucose monitoring (CGM) use has several potential positive effects on diabetes management. These benefits are, e.g., increased time in range (TIR), optimized therapy, and developed documentation. Physical activity is a recommended intervention tool in diabetes management, especially for people with type 2 diabetes (T2D). The benefits of physical activity for people with diabetes can be seen as an improvement of glycemic control, glycemic variability, and the reduction of insulin resistance. In relation to the physical activity of people with T2D, the benefits of CGM use can even be increased, and CGM can be a helpful tool to prevent adverse events due to physical activity of people with diabetes, such as hypoglycemic events and nocturnal hypoglycemia after sports. This narrative review aims to provide solid recommendations for the use of CGM in everyday life physical activities based on the noted benefits and to give a general overview of the guidelines on physical activity and CGM use for people with diabetes.

Blood glucose responses are associated with prolonged sitting-induced changes in arterial stiffness: a randomized crossover trial

OBJECTIVE

To determine whether the vascular dysfunction response to prolonged sitting combined with hyperglycemia can be mitigated with simple and feasible sitting interruption exercises.

METHODS

Twenty healthy young adults [50% women, 21 (2) years, BMI of 21.5 (1.6) kg/m2; (SD)] were enrolled in this study. This study included two 3-h prolonged sitting conditions: uninterrupted sitting (CON) and interruptions with 1-min light half-squat exercises every 20 min (EX). In both conditions, participants ingested 75-g glucose before sitting. The primary outcome was brachial-ankle pulse wave velocity (baPWV).

RESULTS

Linear mixed-effects model analysis revealed a significant interaction effect for baPWV, with a 25% (4.7 m/s) increase for CON and a 1.3% (0.22 m/s) increase for EX. There was also an interaction effect for glucose, with a 60% (57 mg/dl) for CON and a 41% (39 mg/dl) increase for EX. Repeated measures correlation revealed a negligible association between glucose and baPWV for CON (r = -0.04) and a small association for EX (r = 0.32).

CONCLUSION

Vascular dysfunction occurred for the control but not the exercise condition, suggesting interrupting prolonged sitting with regular, short bouts of exercise may be an effective strategy to protect vascular health.

Glycemic variability assessed by continuous glucose monitoring in hospitalized patients with community-acquired pneumonia

Background

Glycemic variability (GV) has only been sparsely studied in patients with community-acquired pneumonia (CAP). This study aimed to quantify in-hospital GV in CAP patients, including determining the impact of type 2 diabetes mellitus (T2DM) and glucocorticoid (GC) treatment on GV.

Methods

This is a prospective cohort study of CAP patients (N = 40) with or without T2DM and treated or not with GCs. The primary endpoint was GV measured as glucose standard deviation (SD), coefficient of variation (CV), and postprandial glucose excursions (PPGE) based on continuous glucose monitoring (CGM). Analysis of glucose data was split into daytime and nighttime when possible.

Results

Patients included had a mean age of 74 (range 55 to 91) years. SD (95%CI) increased by a factor of 1.93 (1.40 to 2.66) and 2.29 (1.38 to 3.81) in patients with T2DM and not treated with GCs during the daytime and the nighttime, respectively (both P < 0.01), and by a factor of 1.42 (1.04 to 1.97) in patients treated with GCs but without T2DM during the daytime (P = 0.031) compared to patients without T2DM and not treated with GCs. CV (95%CI) increased by 5.1 (0.0 to 10.1) and 8.1 (1.0 to 15.2) percentage points during the daytime and the nighttime, respectively, in patients with T2DM and not treated with GCs compared to patients without T2DM and not treated with GCs (P = 0.046 and P = 0.026, respectively). PPGE (95% CI) increased during lunch by 2.5 (0.7 to 4.3) mmol/L (45 (13 to 77) mg/dL) in patients with T2DM and treated with GCs compared to patients without T2DM and not treated with GCs (P = 0.018).

Conclusions

CAP patients receiving GCs, especially those with T2DM, are at great risk of developing high GV and therefore require clinical attention to mitigate GV. This applies particularly during the daytime. Results support the 1 to 2-h post-lunch screening procedure for glucocorticoid-induced hyperglycemia in patients without diabetes. SD was positively correlated with hospital length of stay.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01874-7.

The Effects of Postprandial Walking on the Glucose Response after Meals with Different Characteristics

We evaluated the effect of postprandial walking on the post-meal glycemic response after meals with different characteristics. Twenty-one healthy young volunteers participated in one of two randomized repeated measures studies. Study 1 (10 participants) assessed the effects of 30 min of brisk walking after meals with different carbohydrate (CHO) content (0.75 or 1.5 g of CHO per kg/body weight). Study 2 (11 participants) evaluated the effects of 30 min of brisk walking after consuming a mixed meal or a CHO drink matched for absolute CHO content (75 g). Postprandial brisk walking substantially reduced (p < 0.009) the glucose peak in both studies, with no significant differences across conditions. When evaluating the glycemic response throughout the two hours post-meal, postprandial walking was more effective after consuming a lower CHO content (Study 1), and similarly effective after a mixed meal or a CHO drink (Study 2), although higher glucose values were observed when consuming the CHO drink. Our findings show that a 30 min postprandial brisk walking session improves the glycemic response after meals with different CHO content and macronutrient composition, with implications for postprandial exercise prescription in daily life scenarios.

Associations Between Device-Measured Physical Activity and Glycemic Control and Variability Indices Under Free-Living Conditions

Background: Disturbances of glycemic control and large glycemic variability have been associated with increased risk of type 2 diabetes in the general population as well as complications in people with diabetes. Long-term health benefits of physical activity are well documented but less is known about the timing of potential short-term effects on glycemic control and variability in free-living conditions. Materials and Methods: We analyzed data from 85 participants without diabetes from the Food & You digital cohort. During a 2-week follow-up, device-based daily step count was studied in relationship to glycemic control and variability indices using generalized estimating equations. Glycemic indices, evaluated using flash glucose monitoring devices (FreeStyle Libre), included minimum, maximum, mean, standard deviation, and coefficient of variation of daily glucose values, the glucose management indicator, and the approximate area under the sensor glucose curve. Results: We observed that every 1000 steps/day increase in daily step count was associated with a 0.3588 mg/dL (95% confidence interval [CI]: -0.6931 to -0.0245), a 0.0917 mg/dL (95% CI: -0.1793 to -0.0042), and a 0.0022% (95% CI: -0.0043 to -0.0001) decrease in the maximum glucose values, mean glucose, and in the glucose management indicator of the following day, respectively. We did not find any association between daily step count and glycemic indices from the same day. Conclusions: Increasing physical activity level was linked to blunted glycemic excursions during the next day. Because health-related benefits of physical activity can be long to observe, such short-term physiological benefits could serve as personalized feedback to motivate individuals to engage in healthy behaviors.

Impact of whole-body resistance exercise timing on mitigating hyperglycaemia-induced vascular dysfunction

NEW FINDINGS

What is the central question of this study? Is the estrous cycle affected during disuse atrophies and if so, how do estrous cycle changes relate to musculoskeletal outcomes? What is the main finding and its importance? Rodent estrous cycles are altered during disuse atrophy, which corresponds to musculoskeletal outcomes. However, the estrous cycle does not appear changed in Lewis Lung Carcinoma, which corresponded to no differences in muscle size compared to healthy controls. These findings suggest a relationship between estrous cycle and muscle size during atrophic pathologies.

ABSTRACT

Hyperglycemia can cause disruptions in vascular function, whereas exercise has been shown to restore vascular function. The primary aim of this study is to investigate the effect of performing whole-body resistance exercise, 30-min before, immediately following, or 30- or 60-min after a high carbohydrate meal, on endothelial function, measured by flow-mediated dilation (FMD). Healthy adults will be recruited to this randomized crossover trial to compare the postprandial glycaemic and vascular responses to four different exercise timing conditions and a control: i) C- control, high carbohydrate meal/no exercise, ii) 30Pre- 30 min of resistance exercises (~30% of 1RM [Repetition Maximum]), 30 min before a high carbohydrate meal, iii) IP- 30 min of resistance exercises (~30% of 1RM), immediately following a high carbohydrate meal, iv) 30Post- 30 min of resistance exercises, 30 min after a high carbohydrate meal and v) 60Post- 30 min of resistance exercises, 60 min after a high carbohydrate meal. Measures of metabolic and vascular function will be assessed at baseline and for two hours following the carbohydrate-based breakfast meal.

Does Interrupting Prolonged Sitting With 10- or 20-Min Standing Attenuate Postprandial Glycemia and Blood Pressure in Middle-Aged and Older Adults With Type 2 Diabetes?

We carried out three types of 2-hr experimental sessions with middle-aged and older adults with Type 2 diabetes in order to examine the acute effect of interrupting prolonged sitting with varying periods of standing on postprandial glycemia and blood pressure (BP): (a) prolonged sitting after breakfast; (b) standing for 10 min, 30 min after breakfast; and (c) standing for 20 min, 30 min after breakfast. Glucose and BP were assessed before and after breakfast. A generalized linear model revealed no significant differences for the incremental area under the curve of glucose between standing for 10 min, 30 min after breakfast, versus prolonged sitting after breakfast (β = -4.5 mg/dl/2 hr, 95% CI [-17.3, 8.4]) and standing for 20 min, 30 min after breakfast, versus prolonged sitting after breakfast (β = 0.9 mg/dl/2 hr, 95% CI [-11.9, 13.7]). There was no difference in area under the curve of systolic and diastolic BP among the sessions. Interrupting prolonged sitting time with 10 or 20 min of standing 30 min after breakfast does not attenuate postprandial glycemia or BP in middle-aged and older adults with Type 2 diabetes.

Exercise-nutrient interactions for improved postprandial glycemic control and insulin sensitivity

Type 2 diabetes (T2D) is a rapidly growing yet largely preventable chronic disease. Exaggerated increases in blood glucose concentration following meals is a primary contributor to many long-term complications of the disease that decrease quality of life and reduce lifespan. Adverse health consequences also manifest years prior to the development of T2D due to underlying insulin resistance and exaggerated postprandial concentrations of the glucose-lowering hormone insulin. Postprandial hyperglycemic and hyperinsulinemic excursions can be improved by exercise, which contributes to the well-established benefits of physical activity for the prevention and treatment of T2D. The aim of this review is to describe the postprandial dysmetabolism that occurs in individuals at risk for and with T2D, and highlight how acute and chronic exercise can lower postprandial glucose and insulin excursions. In addition to describing the effects of traditional moderate-intensity continuous exercise on glycemic control, we highlight other forms of activity including low-intensity walking, high-intensity interval exercise, and resistance training. In an effort to improve knowledge translation and implementation of exercise for maximal glycemic benefits, we also describe how timing of exercise around meals and post-exercise nutrition can modify acute and chronic effects of exercise on glycemic control and insulin sensitivity. Novelty: Exaggerated postprandial blood glucose and insulin excursions are associated with disease risk. Both a single session and repeated sessions of exercise improve postprandial glycemic control in individuals with and without T2D. The glycemic benefits of exercise can be enhanced by considering the timing and macronutrient composition of meals around exercise.

AGP und Ernährung – Mit CGM postprandiale Glukoseverläufe analysieren

Ernährungstherapien zählen zu den Grundlagen eines effektiven Diabetesmanagements bei Menschen sowohl mit Typ-1-, als auch mit Typ-2-Diabetes. Auch für Menschen mit Prädiabetes oder Adipositas sind Lebensstilinterventionen, einschließlich Ernährungsempfehlungen, Bestandteil der grundlegenden Therapie. Es wird empfohlen, die Ernährung individuell an die persönlichen Umstände, Präferenzen und metabolischen Ziele anzupassen. Im Zeitalter der Digitalisierung finden mHealth-Interventionen, beispielsweise in Form von kontinuierlich Glukose messenden Systemen (CGM), vermehrt Einzug in die Ernährungstherapie. Das ambulante Glukoseprofil (AGP) zeigt eine strukturierte und grafische Zusammenstellung der durch CGM gewonnenen Daten. Nach einer Bewertung der glykämischen Situation (Hypoglykämien, Variabilität und Stabilität der Glukosewerte) kann das AGP auch als Unterstützung bezüglich einer Ernährungsanpassung dienen. Ziel dieser Publikation ist es, eine allgemeine Übersicht über die Ernährungsempfehlungen, speziell in Deutschland, zu ermöglichen und den Nutzen kontinuierlicher Glukosemessungen in Bezug auf Ernährung zu beschreiben.

Walking Initiated 20 Minutes before the Time of Individual Postprandial Glucose Peak Reduces the Glucose Response in Young Men with Overweight or Obesity: A Randomized Crossover Study

BACKGROUND

Although a single bout of postmeal exercise can lower postprandial glucose (PPG), its optimal timing remains unclear.

OBJECTIVE

This study aimed to investigate the effect of exercise timing using an individualized approach on PPG in overweight or obese young men.

METHODS

Twenty men [age: 23.0 ± 4.3 y; BMI (kg/m2): 27.4 ± 2.8] each completed three 240-min trials in a randomized order separated by 6-14 d: 1) sitting (SIT), 2) walking initiated at each participant's PPG-peak time (PPGP) (iP), and 3) walking initiated 20 min before the PPGP (20iP). For each participant, PPGP was predetermined using continuous glucose monitoring. Walking was performed at 50% maximal oxygen consumption for 30 min. Venous blood was collected at 15- and 30-min intervals for 0-120 min and 120-240 min, respectively. The primary outcome was plasma PPG. Generalized estimating equations were used for comparison between trials.

RESULTS

Compared with SIT, the 4-h incremental AUCs (iAUCs) for plasma PPG (-0.6 mmol · L-1 · h; P = 0.047) and insulin (-28.7%, P < 0.001) were reduced in 20iP only, and C-peptide concentrations were lower after iP (-14.9%, P = 0.001) and 20iP (-28.7%, P < 0.001). Plasma insulin (-11.1%, P = 0.006) and C-peptide (-8.3%, P = 0.012) were lower due to the 20iP compared with iP treatment. Finally, PPG reductions due to iP and 20iP occurred only in men with a BMI > 27.5 kg/m2 (iP, -11.2%; 20iP, -14.7%; P = 0.047) and higher glucose iAUC values during SIT (iP, -25.5%; 20iP, -25.7%; P < 0.001).

CONCLUSIONS

Walking initiated 20 min before PPGP lowered PPG and plasma insulin and C-peptide concentrations in young men with overweight or obesity, in particular in those with high BMI or glucose iAUC values during SIT; it also lowered plasma insulin and C-peptide concentrations more effectively than did exercise initiated at PPGP. This trial was registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn/index.aspx) as ChiCTR1900023175.

AGP and Nutrition - Analysing postprandial glucose courses with CGM

Nutritional therapies are one of the fundamentals of effective management of diabetes type 1 and type 2. Lifestyle interventions, including nutritional recommendations, are also part of the basic therapy for people with prediabetes or obesity. It is recommended that the diet should be individually adapted to personal circumstances, preferences and metabolic goals. In the age of digitalisation, mHealth interventions, like continuous glucose monitoring systems (CGM), are increasingly finding their way into nutrition therapy. The ambulatory glucose profile (AGP), a structured and graphical compilation of the obtained CGM data, can also be used as a support for dietary adjustment. After assessment of the glycaemic situation (hypoglycaemia, variability and stability of glucose levels). This publication aims to provide a general overview of nutritional recommendations, especially in Germany, and to describe the benefits of CGM measurements with regard to nutrition.

Metabolic Effect of Breaking Up Prolonged Sitting with Stair Climbing Exercise Snacks

PURPOSE

Prolonged sitting is associated with cardiometabolic complications. The study purpose was to investigate whether breaking up prolonged sitting with brief stair climbing exercise "snacks" could lower postprandial insulin, glucose, and free fatty acids responses.

METHODS

In two separate randomized crossover studies, 12 young healthy-weight men (study 1) and 11 adults with overweight/obesity (OW; study 2) completed two experimental conditions: i) sedentary (SED; 9-h sitting) and ii) stair climbing snacks (SS; 8 × 15-30 s once per hour). The same high-glycemic index meals were consumed at 0, 3, and 6 h at each condition. The primary outcome was total insulin area under the curve (AUC) across 9 h.

RESULTS

In healthy-weight men, there were no significant differences between SS and SED for total (9-h) insulin AUC (P = 0.24, d = 0.4), total glucose AUC (P = 0.17, d = 0.48), total nonesterified fatty acid (NEFA) AUC (P = 0.22, d = 0.4), or total triglyceride AUC (P = 0.72). In adults with OW, total insulin AUC (-16.5%, P = 0.036, d = 0.94) and total NEFA AUC (-21%, P = 0.016, d = 1.2) were significantly lower in SS versus SED. No differences were found for total glucose and triglyceride AUC (all, P > 0.31) in participants with OW.

CONCLUSIONS

Breaking up 9 h of prolonged sitting with hourly brief stair climbing exercise snacks lowered postprandial insulin and NEFA levels in adults with overweight/obesity.

Accumulating Physical Activity in Short or Brief Bouts for Glycemic Control in Adults With Prediabetes and Diabetes

Clinical practice guidelines on physical activity and diabetes currently stipulate physical activity can be accumulated in bouts of ≥10 minutes to meet recommendations for health benefits. Individuals are also encouraged to interrupt prolonged sitting with brief activity breaks of ∼1 to 5 minutes in duration. Growing research highlights accumulating activity in shorter bouts across the day as a potential strategy to improve glycemic control and to help those who are largely sedentary meet physical activity guidelines. Research has shown favourable glycemic benefits for postprandial glucose and glycated hemoglobin with either 3 short (10 to 15 minutes) or frequent brief (1 to 5 minutes) bouts of activity spread around meals or throughout the day. To date, most studies examining accumulated activity were done with people with type 2 diabetes compared with sedentary conditions, were short term and measured various indices of glycemic control using continuous glucose monitoring. The 7 trials comparing accumulating 3 short bouts to a single bout showed comparable benefits for glycemic control (i.e. fasting glucose, 24 h mean glucose and postprandial hyperglycemia). Furthermore, timing short bouts around meals may improve postprandial glucose and hyperglycemia more than a single bout. It is unknown whether a threshold for the duration of accumulated bouts exists---that is, "how much is enough?" In this narrative review, we focus on the glycemic effects of physical activity accumulated in short or brief bouts for people with prediabetes and diabetes as compared with a single continuous bout. Given that poor adherence to physical activity recommendations and that fewer opportunities exist in modern societies for incidental (nonexercise) physical activity, accumulating activity may be a choice strategy for improving glycemic control in those with and at risk of diabetes.

Glycemic variability: adverse clinical outcomes and how to improve it?

Glycemic variability (GV), defined as an integral component of glucose homoeostasis, is emerging as an important metric to consider when assessing glycemic control in clinical practice. Although it remains yet no consensus, accumulating evidence has suggested that GV, representing either short-term (with-day and between-day variability) or long-term GV, was associated with an increased risk of diabetic macrovascular and microvascular complications, hypoglycemia, mortality rates and other adverse clinical outcomes. In this review, we summarize the adverse clinical outcomes of GV and discuss the beneficial measures, including continuous glucose monitoring, drugs, dietary interventions and exercise training, to improve it, aiming at better addressing the challenging aspect of blood glucose management.

Five Evidence-Based Lifestyle Habits People With Diabetes Can Use

Several evidence-based lifestyle habits focusing on the composition, timing, and sequence of meals and on pre- and postmeal exercise can improve diabetes management. Consuming low-carbohydrate, balanced meals and eating most carbohydrates early in the day are helpful habits. Eating the protein and vegetable components of a meal first and consuming the carbohydrates 30 minutes later can moderate glucose levels. Postmeal glucose surges can be blunted without precipitating hypoglycemia with moderate exercise 30-60 minutes before the anticipated peak. Short-duration, high-intensity exercise could also be effective. Premeal exercise can improve insulin sensitivity but can also cause post-exertion glucose elevations. Moreover, high-intensity premeal exercise may precipitate delayed hypoglycemia in some people. Glycemia benefits can be enhanced by eating a light, balanced breakfast after premeal exercise.