Three 15-min bouts of moderate postmeal walking significantly improves 24-h glycemic control in older people at risk for impaired glucose tolerance

Morning physical activity may be more beneficial for blood lipids than afternoon physical activity in older adults: a cross-sectional study

BACKGROUND

The effect of differences in daily physical activity patterns on blood lipids has not been determined. This study examines the effects of the differences in free-living daily physical activity patterns (amount and intensity) on blood lipid levels in older adults.

METHODS

This cross-sectional study included 51 older participants (71.8 ± 0.6 years, men = 8, women = 43). A triaxial accelerometer was used to assess physical activity patterns. The time from awakening to bedtime for each participant was used for group classification based on the amount (number of steps) and intensity (moderate-to-vigorous physical activity, MVPA) of physical activity. The morning step group (M Step) was defined as those who took more steps in the morning, and the afternoon step group (A Step) was defined as those who took more steps in the afternoon. The same method was used for MVPA (morning MVPA: M MVPA; afternoon MVPA: A MVPA). Blood samples were collected at the start of the study to determine blood lipid levels.

RESULTS

Number of steps taken showed a trend toward lower low-density lipoprotein cholesterol (LDL-C) levels in the M Step group compared with the A Step group. The LDL/high-density lipoprotein (HDL) ratio was significantly lower in the M Step group than the A Step group (p < 0.05). The M MVPA group also had higher HDL-C levels and significantly lower LDL/HDL ratios than the A MVPA group (p < 0.05).

CONCLUSIONS

These results suggest that compared with afternoon physical activity, daily morning physical activity (amount and intensity) is more effective in improving blood lipid levels.

Diagnosis to Delivery: A Randomized Clinical Trial of Postmeal Walking in Women with Gestational Diabetes

PURPOSE

The aim of this study was to determine whether advice to perform postmeal walking could be an effective and feasible alternate to standard care continuous walking for the management of gestational diabetes (GDM).

METHODS

Forty women with GDM were randomized between 28 and 30 wk of gestation into either standard care (CTL; 30-min continuous walking, most days per week) or standard care with advice to PMW (daily 10-min walks after three main meals) for ~7 wk. The primary outcome for this randomized controlled trial was postprandial glucose assessed by continuous glucose monitors. Continuous glucose monitor and ActivPAL inclinometers (physical activity parameters) were each worn for 7 d at ~28 and ~35 wk gestation. Delivery outcomes were also collected. A linear mixed model compared the changes across time between groups.

RESULTS

Twenty-six women (PMW: n = 12, CTL: n = 14; age 34 ± 5 y) completed the trial. Mean 3 h postprandial glucose at dinner was higher in the PMW versus CTL group at baseline and across the intervention (main effect group, P = 0.04). Twenty-four hours, nocturnal, and fasting glucose were similar between groups. The PMW group spent ~57 min·d -1 more time sedentary and ~11 min·d -1 less time stepping versus CTL (main effect group: P = 0.02 and 0.05). Adherence to the prescribed 30 min·d -1 of physical activity was high, regardless of whether accumulated as 3 × 10-min or one single bout of walking.

CONCLUSIONS

Distributing activity as 10-min bouts after main meals did not improve postprandial glucose outcomes compared with standard-care control. More research on the optimal duration and intensity of postmeal walks to improve postprandial responses are needed. Strategies that mitigate sedentary time and increase the minutes of physical activity accumulated across the day in pregnancy are also warranted.

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.

Understanding the variation in exercise responses to guide personalized physical activity prescriptions

Understanding the factors that contribute to exercise response variation is the first step in achieving the goal of developing personalized exercise prescriptions. This review discusses the key molecular and other mechanistic factors, both extrinsic and intrinsic, that influence exercise responses and health outcomes. Extrinsic characteristics include the timing and dose of exercise, circadian rhythms, sleep habits, dietary interactions, and medication use, whereas intrinsic factors such as sex, age, hormonal status, race/ethnicity, and genetics are also integral. The molecular transducers of exercise (i.e., genomic/epigenomic, proteomic/post-translational, transcriptomic, metabolic/metabolomic, and lipidomic elements) are considered with respect to variability in physiological and health outcomes. Finally, this review highlights the current challenges that impede our ability to develop effective personalized exercise prescriptions. The Molecular Transducers of Physical Activity Consortium (MoTrPAC) aims to fill significant gaps in the understanding of exercise response variability, yet further investigations are needed to address additional health outcomes across all populations.

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.

Walking pace and microvascular complications among individuals with type 2 diabetes: A cohort study from the UK Biobank

INTRODUCTION

Walking pace is associated with various health-related outcomes. The aim of this study was to investigate the association between self-reported walking pace and the incidences of diabetic microvascular complications among participants with type 2 diabetes (T2D).

METHODS

Self-reported walking pace was classified as brisk, average, or slow. The outcomes were the incidences of diabetic retinopathy, diabetic neuropathy, and diabetic nephropathy. COX proportional hazards models adjusted for sociodemographic, lifestyle, and health-related factors were used to estimate hazard ratios (HRs) and 95% CIs.

RESULTS

A total of 14 518 participants with T2D in the UK Biobank (mean age 59.7 ± 7.0 years, 5028 [34.6%] women) were included. During a median follow-up of 12.5 (interquartile range: 11.6-13.4) years, 2980 participants developed diabetic microvascular complications. After adjusting for confounding factors, and compared with brisk walkers, slow walkers had a multivariable-adjusted HR of 1.98 (95% CI 1.58, 2.47) for composite diabetic microvascular complications, 1.54 (95% CI 1.11, 2.14) for diabetic retinopathy, 3.26 (95% CI 2.08, 5.11) for diabetic neuropathy, and 2.32 (95% CI 1.91, 2.82) for diabetic nephropathy. Average walking pace was associated with a higher risk for diabetic nephropathy (HR 1.51, 95 CI% 1.27-1.79) compared with brisk walking. Additionally, ≥1 diabetic microvascular complication occurred in 447 (14.7%) of participants with brisk walking pace, 1702 (19.5%) with average walking pace, and 831 (30.4%) with slow walking pace. Time from study recruitment to first diagnosis was shorter in participants who reported a slow walking pace, compared with brisk or average walkers. Among participants who had diabetic nephropathy as their first diagnosis, slow walking pace was associated with subsequent risk of a second diabetic microvascular complication (HR 3.88, 95 CI% 2.27-6.60).

CONCLUSIONS

Self-reported slow walking pace is associated with a higher risk of diabetic microvascular complications among participants with T2D in this population-based cohort study.

Type 2 Diabetes Mellitus and Sarcopenia as Comorbid Chronic Diseases in Older Adults: Established and Emerging Treatments and Therapies

Type 2 diabetes mellitus (T2DM) and sarcopenia (low skeletal muscle mass and function) share a bidirectional relationship. The prevalence of these diseases increases with age and they share common risk factors. Skeletal muscle fat infiltration, commonly referred to as myosteatosis, may be a major contributor to both T2DM and sarcopenia in older adults via independent effects on insulin resistance and muscle health. Many strategies to manage T2DM result in energy restriction and subsequent weight loss, and this can lead to significant declines in muscle mass in the absence of resistance exercise, which is also a first-line treatment for sarcopenia. In this review, we highlight recent evidence on established treatments and emerging therapies targeting weight loss and muscle mass and function improvements in older adults with, or at risk of, T2DM and/or sarcopenia. This includes dietary, physical activity and exercise interventions, new generation incretin-based agonists and myostatin-based antagonists, and endoscopic bariatric therapies. We also highlight how digital health technologies and health literacy interventions can increase uptake of, and adherence to, established and emerging treatments and therapies in older adults with T2DM and/or sarcopenia.

Efficacy of Postprandial Exercise in Mitigating Glycemic Responses in Overweight Individuals and Individuals with Obesity and Type 2 Diabetes-A Systematic Review and Meta-Analysis

Studies investigating the acute effect of postprandial exercise (PPE) on glucose responses exhibit significant heterogeneity in terms of participant demographic, exercise protocol, and exercise timing post-meal. As such, this study aimed to further analyze the existing literature on the impact of PPE on glycemic control in overweight individuals and individuals with obesity and type 2 diabetes (T2DM). A literature search was conducted through databases such as PubMed, CINAHL, and Google Scholar. Thirty-one original research studies that met the inclusion criteria were selected. A random-effect meta-analysis was performed to compare postprandial glucose area under the curve (AUC) and 24 h mean glucose levels between PPE and the time-matched no-exercise control (CON). Subgroup analyses were conducted to explore whether the glucose-lowering effect of PPE could be influenced by exercise duration, exercise timing post-meal, and the disease status of participants. This study revealed a significantly reduced glucose AUC (Hedges' g = -0.317; SE = 0.057; p < 0.05) and 24 h mean glucose levels (Hedges' g = -0.328; SE = 0.062; p < 0.05) following PPE compared to CON. The reduction in glucose AUC was greater (p < 0.05) following PPE lasting >30 min compared to ≤30 min. The reduction in 24 h mean glucose levels was also greater (p < 0.05) following PPE for ≥60 min compared to <60 min post-meal and in those with T2DM compared to those without T2DM. PPE offers a viable approach for glucose management and can be performed in various forms so long as exercise duration is sufficient. The glucose-lowering effect of PPE may be further enhanced by initiating it after the first hour post-meal. PPE is a promising strategy, particularly for patients with T2DM. This manuscript is registered with Research Registry (UIN: reviewregistry1693).

The importance of exercise for glycemic control in type 2 diabetes

Exercise is a first-line therapy recommended for patients with type 2 diabetes (T2D). Although moderate to vigorous exercise (e.g. 150 min/wk) is often advised alongside diet and/or behavior modification, exercise is an independent treatment that can prevent, delay or reverse T2D. Habitual exercise, consisting of aerobic, resistance or their combination, fosters improved short- and long-term glycemic control. Recent work also shows high-intensity interval training is successful at lowering blood glucose, as is breaking up sedentary behavior with short-bouts of light to vigorous movement (e.g. up to 3min). Interestingly, performing afternoon compared with morning as well as post-meal versus pre-meal exercise may yield slightly better glycemic benefit. Despite these efficacious benefits of exercise for T2D care, optimal exercise recommendations remain unclear when considering, dietary, medication, and/or other behaviors.

Is There an Optimal Time of Day for Exercise? A Commentary on When to Exercise for People Living With Type 1 or Type 2 Diabetes

Exercise is a cornerstone of diabetes self-care because of its association with many health benefits. Several studies that have explored the best time of day to exercise to inform clinical recommendations have yielded mixed results. For example, for people with prediabetes or type 2 diabetes, there may be benefits to timing exercise to occur after meals, whereas people with type 1 diabetes may benefit from performing exercise earlier in the day. One common thread is the health benefits of consistent exercise, suggesting that the issue of exercise timing may be secondary to the goal of helping people with diabetes establish an exercise routine that best fits their life.

Associations of timing of physical activity with all-cause and cause-specific mortality in a prospective cohort study

There is a growing interest in the role of timing of daily behaviors in improving health. However, little is known about the optimal timing of physical activity to maximize health benefits. We perform a cohort study of 92,139 UK Biobank participants with valid accelerometer data and all-cause and cause-specific mortality outcomes, comprising over 7 years of median follow-up (638,825 person-years). Moderate-to-vigorous intensity physical activity (MVPA) at any time of day is associated with lower risks for all-cause, cardiovascular disease, and cancer mortality. In addition, compared with morning group (>50% of daily MVPA during 05:00-11:00), midday-afternoon (11:00-17:00) and mixed MVPA timing groups, but not evening group (17:00-24:00), have lower risks of all-cause and cardiovascular disease mortality. These protective associations are more pronounced among the elderly, males, less physically active participants, or those with preexisting cardiovascular diseases. Here, we show that MVPA timing may have the potential to improve public health.

Evolution of the diagnostic value of "the sugar of the blood": hitting the sweet spot to identify alterations in glucose dynamics

In this paper, we provide an overview of the evolution of the definition of hyperglycemia during the past century and the alterations in glucose dynamics that cause fasting and postprandial hyperglycemia. We discuss how extensive mechanistic, physiological research into the factors and pathways that regulate the appearance of glucose in the circulation and its uptake and metabolism by tissues and organs has contributed knowledge that has advanced our understanding of different types of hyperglycemia, namely prediabetes and diabetes and their subtypes (impaired fasting plasma glucose, impaired glucose tolerance, combined impaired fasting plasma glucose, impaired glucose tolerance, type 1 diabetes, type 2 diabetes, gestational diabetes mellitus), their relationships with medical complications, and how to prevent and treat hyperglycemia.

Gender Differences in Unhealthy Lifestyle Behaviors among Adults with Diabetes in the United States between 1999 and 2018

Lifestyle management is important to patients with diabetes, but whether gender differences exist in lifestyle management is unclear. Data from the US National Health and Nutrition Examination Survey (NHANES 1999 to 2018) was used for this research. Gender differences were evaluated descriptively and using an odds ratio (OR) with a 95% confidence interval (CI). A total of 8412 participants (48% women) were finally included. Across these surveys, the incidences of poor diet (OR: 1.26 (95% CI, 1.12, 1.43)), smoking (1.58 (1.35, 1.84)), alcohol consumption (1.94 (1.68, 2.25)) and sedentary behavior (1.20 (1.04, 1.39)) were more common in men, while depression (0.47 (0.37, 0.59)), obesity (0.69 (0.61, 0.78)) and insufficient physical activity (0.56 (0.49, 0.65)) were more common in women. Reductions in poor diet were greater in men between 1999 and 2000 and 2017 and 2018 (p = 0.037), while the mean body mass index (BMI) levels (p = 0.019) increased more among women. Furthermore, several gender differences were found to be related to age, race/ethnicity and marital/insurance/employment statuses. Our research found gender differences in diabetes-related unhealthy lifestyle behaviors and provides reference data for implementing measures to reduce the gender differences. Further work to reduce gender-specific barriers to a healthy lifestyle is warranted in order to further improve diabetes management.

The effect of postprandial exercise on mean blood glucose concentrations following high and maintenance carbohydrate content meals in healthy dogs

OBJECTIVES

To compare the effect of 15 min of exercise 30 min post-meal on mean blood glucose concentrations in 5 well-conditioned versus 5 over-conditioned dogs. To compare the effect of exercise on glycemic control in dogs eating their maintenance diet as compared to a high carbohydrate meal.

ANIMALS

Ten healthy staff or student owned dogs, five well- and five over-conditioned.

PROCEDURES

This was a crossover study over 5 days. Continuous glucose monitors (CGM) were placed on day 1. On days 2 and 3, dogs received their maintenance diet and a high carbohydrate meal, respectively and were walked on the treadmill for 15 min following each meal. On day 4, dogs were given their maintenance diet in hospital without treadmill activity. On day 5, the CGM were removed. The mean blood glucose 30 min post-meal, during exercise, 15 min after completing exercise, and the 1-3 h period after completing the exercise were compared to detect any effect of exercise, diet composition, or body condition.

RESULTS

Dogs consuming a high carbohydrate meal had a significantly higher mean blood glucose 15 min post-exercise. Mean glucose values at all time points following a high carbohydrate meal were significantly higher than mean glucose values on the non-exercise day.

CONCLUSIONS AND CLINICAL RELEVANCE

No impact of post-prandial exercise on glucose concentrations were identified in this study, however, the carbohydrate content of the meal impacted post-prandial glycemic responses in healthy dogs regardless of body condition. Evaluating the impact of post-prandial exercise in insulin-dependent or glucose-intolerant dogs is warranted to determine if these findings persist.

Using wearable biological sensors to provide personalized feedback to motivate behavioral changes: Study protocol for a randomized controlled physical activity intervention in cancer survivors (Project KNOWN)

Regular physical activity reduces the progression of several cancers and offers physical and mental health benefits for cancer survivors. However, many cancer survivors are not sufficiently active to achieve these health benefits. Possible biological mechanisms through which physical activity could affect cancer progression include reduced systemic inflammation and positive changes in metabolic markers. Chronic and acute hyperglycemia could have downstream effects on cell proliferation and tumorigenesis. One novel strategy to motivate cancer survivors to be more active is to provide personalized biological-based feedback that demonstrates the immediate positive impact of physical activity. Continuous glucose monitors (CGMs) have been used to demonstrate the acute beneficial effects of physical activity on insulin sensitivity and glucose metabolisms in controlled lab settings. Using personal data from CGMs to illustrate the immediate impact of physical activity on glucose patterns could be particularly relevant for cancer survivors because they are at a higher risk for developing type 2 diabetes (T2D). As a pilot project, this study aims to (1) test the preliminary effect of a remotely delivered physical activity intervention that incorporates personalized biological-based feedback on daily physical activity levels, and (2) explore the association between daily glucose patterns and cancer-related insulin pathway and inflammatory biomarkers in cancer survivors who are at high risk for T2D. We will recruit 50 insufficiently active, post-treatment cancer survivors who are at elevated risk for T2D. Participants will be randomly assigned into (1) a group that receives personalized biological feedback related to physical activity behaviors; and (2) a control group that receives standard educational material. The feasibility and preliminary efficacy of this wearable sensor-based, biofeedback-enhanced 12-week physical activity intervention will be evaluated. Data from this study will support the further refinement and enhancement of a more comprehensive remotely delivered physical activity intervention that targets cancer survivors.

Trial registration: ClinicalTrials.gov Identifier: NCT05490641.

The Effects of Accumulated Versus Continuous Exercise on Postprandial Glycemia, Insulin, and Triglycerides in Adults with or Without Diabetes: A Systematic Review and Meta-Analysis

BACKGROUND

Postprandial dysmetabolism, an important cardiovascular disease risk factor, can be improved by exercise. Further systematic review and meta-analysis is needed to compare the effects of accumulated exercise with a single session of energy-matched continuous exercise on postprandial glucose (PPG), insulin, and triglycerides in adults with or without diabetes.

METHODS

Eight electronic databases were searched on August 28, 2020, and updated on April 27, 2021. Eligible studies were randomized, quasi-randomized, or non-randomized controlled or crossover trials that evaluated the acute or longitudinal effects of accumulated exercise compared with a single session of energy-matched continuous exercise on PPG, postprandial insulin, and triglycerides in diabetic and non-diabetic adults. Same-day and second-morning effects were assessed separately for acute intervention studies. Subgroup analyses were conducted based on the number of exercise bouts (2-3 bouts or frequent brief bouts (e.g., 1-6 min) throughout the day at 20-60-min intervals (known as physical activity [PA] breaks, ≥ 5 bouts)), exercise intensity, and populations. Risk of bias was assessed using the revised Cochrane risk-of-bias tool for randomized trials. Pooled effects were reported as standardized mean differences (SMD) and 95% CI using a random effects model.

RESULTS

Twenty-seven studies (635 participants) were included. A significant difference was found for same-day PPG control, which favored accumulated exercise over one bout of energy-matched continuous exercise (SMD - 0.36 [95%CI: (- 0.56, - 0.17)], P = 0.0002, I2 = 1%), specifically in accumulated exercise with PA breaks (SMD - 0.36 [95%CI: (- 0.64, - 0.08)], P = 0.01, I2 = 30%), low-moderate intensity exercise (SMD - 0.38 [(95%CI: (- 0.59, - 0.17)], P = 0.0005, I2 = 0%), and in non-diabetic populations (SMD - 0.36 [95%CI: (- 0.62, - 0.10)], P = 0.007, I2 = 16%). No differences were found for same-day postprandial insulin and triglycerides, and second-morning effects (postprandial or fasting glucose, insulin, and triglycerides) between different exercise patterns.

CONCLUSION

Compared with one session of continuous exercise, accumulated exercise-specifically in subgroups of PA breaks, low-moderate intensity exercises-produced greater acute effects on same-day PPG control for non-diabetic adults. There were no differences between continuous and accumulated patterns of exercise in terms of same-day postprandial insulin and triglycerides, and second-morning effects on all previously mentioned markers. The findings provide additional PA options for PPG control for individuals with limited time or exercise capacity to engage in PA in one session. Registration: PROSPERO (identification code: CRD42021251325).

Environmental Factors as Diabetic Mediators: A Mechanistic Approach

Despite substantial investment in research and treatment options, diabetes mellitus remains a pressing public health concern with potential epidemic proportions globally. There are reports that by the end of 2040, 642 million people will be suffering from diabetes. Also, according to an estimation, 1.6 million deaths were caused directly by diabetes in 2016. Diabetes is a metabolic disorder characterized by impaired glucose regulation in the body due to the destruction of pancreatic β-cells or insulin resistance. Genetic propensity, unhealthy and imbalanced diet, obesity and increasing urbanization are the common risk factors for diabetes. Besides this, it has been reported that environmental pollutants like organic pesticides, heavy metals, and air pollutants act as strong predisposing factors for diabetes owing to their highly bio-accumulative nature. These pollutants disturb glucose homeostasis either by up-regulating or down-regulating the expression of diabetic marker genes like insulin (INS) and glucokinase (GCK). Unfortunately, the molecular mechanism of the role of pollutants in causing diabetes is not very clear. This mechanistic review provides evidence of different environmental determinants, including persistent organic pollutants (POPs), air pollutants, toxic metals, etc., in inducing diabetes and proposes a framework for the possible mechanisms involved. It also illuminates the current status and future challenges, which will not only broaden our understanding but can also be a reasonable platform for further investigation.

Acute high intensity interval exercise is similarly effective as moderate intensity continuous exercise on plasma glucose control in type 2 diabetic men aged 30 to 50 years: a randomized controlled trial

BACKGROUND

This study aimed to compare the acute effects of high-intensity interval exercise (HIIE) versus moderate-intensity continuous exercise (MICE) on postprandial plasma glucose and insulin concentrations in men aged 30-50 years with type 2 diabetes (T2D), hoping to provide empirical evidence for the effects of different exercise types on glucose management in T2D patients.

METHODS

14 men with type 2 diabetes (T2D) underwent a randomized three crossover intervention: HIIE with cycling; energy expenditure matched MICE with cycling; and a sedentary control (CON)) in postprandial state. Plasma glucose and insulin levels were measured at pre-exercise, post-exercise, 1 h post-exercise, pre-lunch and 1 h post-lunch, respectively. Responses of areas under the curve (AUC) during 4 h from pre-exercise to 1 h post-lunch were also calculated.

RESULTS

Both HIIE and MICE decreased plasma glucose and insulin levels during 4 h experimental period compared to CON, with significant intervention × time interaction effects for glucose (P = 0.001) and insulin (P = 0.006) values evolution. Area under curve (AUCs) for glucose and insulin were reduced in HIIE and MICE compared to CON (P < 0.05), whereas no differences were found between HIIE and MICE.

CONCLUSIONS

Acute HIIE and the matched MICE improve plasma glucose control in the same magnitude in type 2 diabetic men aged 30-50 years.

Timing of Meals and Exercise Affects Hormonal Control of Glucoregulation, Insulin Resistance, Substrate Metabolism, and Gastrointestinal Hormones, but Has Little Effect on Appetite in Postmenopausal Women

The current prevalence of obesity in the US is strongly associated with excessive food intake and insufficient physical activity. This study examined whether changing the timing of exercise before or after two daily meals could alter human appetite for food. Fifty-four healthy postmenopausal women were matched by body weight and assigned to two groups: (1) two bouts of 2-h moderate-intensity exercise ending one hour before each weight-maintenance meal (XM, n = 23), (2) two-hour moderate-intensity exercise starting 1 h after each weight-maintenance meal (MX, n = 23), and one sedentary control (SED) arm (n = 8). Measurements included appetite ratings, circulating glucose, free fatty acids (FFAs), a ketone body D-ß-hydroxybutyrate (BHB), glucoregulatory hormones insulin and glucagon, and gastrointestinal hormones associated with food digestion and absorption and implicated in appetite sensations. XM group increased concentrations of FFAs and BHB during exercise and increased insulin and homeostatic assessment of insulin resistance (HOMA-IR) during postprandial periods. MX group reduced postprandial insulin and HOMA-IR by about 50% without a major change in plasma glucose. There was brief suppression of hunger and an increase in satiation in both exercise groups near the end of the first postprandial period. The time course of hunger was unrelated to the perturbations in fuel metabolism, depletion of liver glycogen, and not correlated with concentration changes in hunger-stimulating hormone ghrelin during XM exercise before meals. Similarly, there was no correlation between the time course of fullness during exercise after meals with the postprandial secretion of gastrointestinal hormones including cholecystokinin (CCK) that has been linked to satiation. Hunger and satiation appear to depend on oral intake and gastrointestinal processing of nutrients and are not affected by metabolic and hormonal consequences of the timing of exercise with respect to meals. Moderate-intensity exercise performed shortly after meals induces a rapid and highly effective lowering of insulin resistance.

Time-of-day moderate-to-vigorous physical activity and all-cause mortality in individuals with type 2 diabetes

There is no clear evidence for the best time of day for physical activity in benefitting health among individuals with type 2 diabetes. This study was aimed to examine whether there is an optimal time of day for physical activity to increase longevity. In this cohort study of 904 patients with type 2 diabetes, we fitted a Cox model with restricted cubic spline to examine the association of moderate-to-vigorous physical activity (MVPA) and time of day with all-cause mortality. Compositional data analysis was used to examine the association of time spent in sedentary behaviour (SB), light-intensity physical activity (LIPA), morning MVPA, and evening MVPA with all-cause mortality. MVPA was inversely associated with all-cause mortality in a curvilinear manner (P-value for nonlinearity<0.0001). The interaction between MVPA and time of day was not significant (P-value for interaction=0.11). Substituting evening MVPA with morning MVPA was not associated with appreciable changes in all-cause mortality. There is no evidence that the time of day moderates the association of MVPA with all-cause mortality. Patients with higher levels of MVPA had lower mortality regardless of the timing of MVPA. Patients with type 2 diabetes should engage in regular physical activity whenever possible.

Accuracy of Flash Glucose Monitoring During Postprandial Rest and Different Walking Conditions in Overweight or Obese Young Adults

Aims: To investigate the accuracy of FreeStyle Libre^TM flash glucose monitoring (FGM) relevant to plasma glucose (PG) measurements during postprandial rest and different walking conditions in overweight/obese young adults. Methods: Data of 40 overweight/obese participants from two randomized crossover studies were pooled into four trials: (1) sitting (SIT, n = 40); (2) walking continuously for 30 min initiated 20 min before individual postprandial glucose peak (PPGP) (20iP + CONT, n = 40); (3) walking continuously for 30 min initiated at PPGP (iP + CONT, n = 20); and (4) accumulated walking for 30 min initiated 20 min before PPGP (20iP + ACCU, n = 20). Paired FGM and PG were measured 4 h following breakfast. Results: The overall mean absolute relative difference (MARD) between PG and FGM readings was 16.4 ± 8.6% for SIT, 16.2 ± 4.7% for 20iP + CONT, 16.7 ± 12.2% for iP + CONT, and 19.1 ± 6.8% for 20iP + ACCU. The Bland-Altman analysis showed a bias of -1.03 mmol⋅L^-1 in SIT, -0.89 mmol⋅L^-1 in 20iP + CONT, -0.82 mmol⋅L^-1 in iP + CONT, and -1.23 mmol⋅L^-1 in 20iP + ACCU. The Clarke error grid analysis showed that 99.6-100% of the values in all trials fell within zones A and B. Conclusion: Although FGM readings underestimated PG, the FGM accuracy was overall clinically acceptable during postprandial rest and walking in overweight/obese young adults.

Postprandial interval walking-effect on blood glucose in pregnant women with gestational diabetes

BACKGROUND

During pregnancy, postprandial hyperglycemia may increase the risk of complications such as fetal macrosomia. However, evidence on beneficial effects of physical activity on postprandial hyperglycemia is sparse.

OBJECTIVE

This study aimed to investigate the effect of 20 minutes of postprandial interval walking on glycemic control and glycemic variability in pregnant women diagnosed as having gestational diabetes mellitus.

STUDY DESIGN

A crossover controlled trial including 14 pregnant women (gestational age 31.8±1.3 weeks) diagnosed as having gestational diabetes mellitus (75 g oral glucose load with 2-hour venous plasma glucose of ≥9.0 mmol/L) was conducted. Participants completed a 4-day intervention period and a 4-day control period with 3 days in between. In each study period, participants received a fixed and identical diet. In the intervention period, participants engaged in 20 minutes of postprandial interval walking after breakfast, lunch, and dinner. Interval walking comprised alternating 3 minutes of slow and fast intervals. Interstitial glucose concentrations were determined during both study periods with a continuous glucose monitor. The mixed effects model was used to compare differences between exercise and no exercise.

RESULTS

Of note, 20 minutes of postprandial interval walking significantly reduced glycemic control during daytime hours relative to the control period (4-day mean glucose, 5.31 [5.04-5.59] vs 5.53 [5.25-5.81] mmol/L [95.6 (90.7-100.6) vs 99.5 (94.5-104.6) mg/dL]; P<.05). On each individual trial day, interval walking significantly reduced glycemic control during daytime hours on day 1 (mean glucose, 5.19 [4.92-5.47] vs 5.55 [5.27-5.83] mmol/L [93.4 (88.6-98.5) vs 99.9 (94.9-104.9) mg/dL]; P=.00), day 2 (mean glucose, 5.32 [5.05-5.60] vs 5.57 [5.29-5.84] mmol/L [95.8 (90.9-100.8) vs 100.3 (95.2-105.1) mg/dL]; P=.00), and day 3 (mean glucose, 5.27 [5.00-5.54] vs 5.46 [5.19-5.74] mmol/L [94.9 (90.0-99.7) vs 98.3 (93.4-103.3) mg/dL]; P=.00), but not on day 4.

CONCLUSION

A total of 20 minutes of postprandial interval walking seems to be an effective way to control postprandial glucose excursions in women with gestational diabetes mellitus.

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.

Considerations for Maximizing the Exercise "Drug" to Combat Insulin Resistance: Role of Nutrition, Sleep, and Alcohol

Insulin resistance is a key etiological factor in promoting not only type 2 diabetes mellitus but also cardiovascular disease (CVD). Exercise is a first-line therapy for combating chronic disease by improving insulin action through, in part, reducing hepatic glucose production and lipolysis as well as increasing skeletal muscle glucose uptake and vasodilation. Just like a pharmaceutical agent, exercise can be viewed as a "drug" such that identifying an optimal prescription requires a determination of mode, intensity, and timing as well as consideration of how much exercise is done relative to sitting for prolonged periods (e.g., desk job at work). Furthermore, proximal nutrition (nutrient timing, carbohydrate intake, etc.), sleep (or lack thereof), as well as alcohol consumption are likely important considerations for enhancing adaptations to exercise. Thus, identifying the maximal exercise "drug" for reducing insulin resistance will require a multi-health behavior approach to optimize type 2 diabetes and CVD care.

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.

Effect of postprandial moderate-intensity walking for 15-min on glucose homeostasis in type 2 diabetes mellitus patients

Aim

Diabetes patients usually have a low activity level and complain about lack of time. Therefore, we investigated the effect of short time, postprandial moderate-intensity exercise on glucose homeostasis in type 2 diabetes patients.

Methods

Eleven patients with type 2 diabetes were recruited. Patients spent the first day of the study without exercise (non-exercise day; NE day). In the second day, they walked at moderate-intensity (40% of the maximum heart rate reserve) for 15 min, 30 min after each meal (exercise day; E day). Glucose homeostasis was estimated by a continuous glucose monitor (CGM). All meals during the study were of standard composition. We compared NE day and E day concerning 24-h glucose homeostasis and 3 h postprandial glucose levels by the incremental area under the curve (iAUC) method. Medications were not changed during the study.

Results

The number of patients under basal supported oral therapy, intensive insulin therapy and oral hypoglycemic agents (OHA) were 5, 4 and 2, respectively. The blood glucose standard deviation over 24 h and the iAUC for the 24-h glycemic variability (NE day vs. E day; 34,765 [21,424-56,014] vs. 23,205 [15,323-39,779]) were smaller in E day than in NE day.

Conclusion

These results suggest that postprandial moderate-intensity walking, easily performable in daily life activities, was effective for improving glucose homeostasis. Further study should be performed to clarify the relationship between postprandial walk and drug therapy (insulin and OHA), including insulin secretory ability.

Why are physical activity breaks more effective than a single session of isoenergetic exercise in reducing postprandial glucose? A systemic review and meta-analysis

Previous studies revealed that interrupting sitting time with short, frequent physical activity (PA) breaks were more effective than a single session of isoenergetic exercise in reducing postprandial glucose. However, in those studies, the expected glucose-lowering effects of single-session exercises were diminished or even eliminated by exercise-induced glucose counterregulation as evidenced by the higher glucose levels during or after exercise compared to uninterrupted sitting. This study was aimed to investigate whether glucose counterregulation is a potential explanation of PA breaks being more effective than a single session of isoenergetic exercise in reducing postprandial glucose. We meta-analysed the standardized mean differences (SMD) of glucose incremental area under the curve (iAUC). PA breaks were more effective than single-session exercise in reducing glucose iAUC (5 studies, SMD = -0.581; 95% confidence interval [CI], -0.777 to -0.385; P < 0.0001) when exercise-induced glucose counterregulation occurred. There was no significant difference in glucose iAUC between PA breaks and single-session exercises (2 studies, SMD = 0.302; 95% CI, -0.107 to 0.711; P = 0.451) when glucose counterregulation did not occur. We concluded that the exercise-induced glucose counterregulation was a potential explanation of PA breaks being more effective than a single session of isoenergetic exercise in reducing postprandial glucose responses. (PROSPERO ID: CRD42020175737).

An NP's guide to current physical activity recommendations

Physical inactivity is a public health crisis that contributes to many of the chronic diseases that affect Americans. This review emphasizes the beneficial health implications of physical activity along with the dangers of sedentary lifestyles. It also provides advice tailored to NPs to help their patients become more physically active.

Multiple short bouts of exercise are better than a single continuous bout for cardiometabolic health: a randomised crossover trial

PURPOSE

To compare cardiometabolic responses to five consecutive days of daily postprandial exercise accumulated in three 10-min bouts or a single 30-min bout to a no-exercise control.

METHODS

Ten insufficiently active adults completed three trials in a randomised order. Each trial comprised five consecutive days of 30 min of exercise either accumulated in three separate 10-min bouts (ACC) after main meals; a single 30-min bout after dinner (CONT); or a no-exercise control (NOEX). Glucose regulation was assessed from an oral glucose tolerance test. Applanation tonometry was used to assess pulse wave velocity approximately 12 h following completion of the final trial.

RESULTS

Area under the 2-h glucose curve was similar for CONT (mean; 95% CI 917 mmol L^-1 2 h^-1; 815 to 1019) and ACC (931 mmol L^-1 2 h^-1; 794 to 1068, p = 0.671). Area under the 2-h insulin curve was greater following NOEX (70,328 pmol L^-1 2 h^-1; 30,962 to 109,693) than ACC (51,313 pmol L^-1 2 h^-1: 21,822 to 80,806, p = 0.007). Pulse wave velocity was lower for ACC (5.96 m s^-1: 5.38 to 6.53) compared to CONT (6.93 m s^-1: 5.92 to 7.94, p = 0.031) but not significantly lower for ACC compared to NOEX (6.52 m s^-1: 5.70 to 7.34, p = 0.151).

CONCLUSION

Accumulating 30 min of moderate-intensity walking in three bouts throughout the day is more effective at reducing markers of cardiometabolic health risk in insufficiently active, apparently healthy adults than a single daily bout. Both accumulated and single-bout walking were equally as effective at reducing postprandial glucose concentrations compared to a no-exercise control. Therefore, accumulating exercise in short bouts after each main meal might be more advantageous for overall cardiometabolic health.

Effects of Interrupting Prolonged Sitting with Physical Activity Breaks on Blood Glucose, Insulin and Triacylglycerol Measures: A Systematic Review and Meta-analysis

BACKGROUND

Physical activity (PA) breaks in sitting time might attenuate metabolic markers relevant to the prevention of type 2 diabetes.

OBJECTIVES

The primary aim of this paper was to systematically review and meta-analyse trials that compared the effects of breaking up prolonged sitting with bouts of PA throughout the day (INT) versus continuous sitting (SIT) on glucose, insulin and triacylglycerol (TAG) measures. A second aim was to compare the effects of INT versus continuous exercise (EX) on glucose, insulin and TAG measures.

METHODS

The review followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) recommendations. Eligibility criteria consisted of trials comparing INT vs. SIT or INT vs. one bout of EX before or after sitting, in participants aged 18 or above, who were classified as either metabolically healthy or impaired, but not with other major health conditions such as chronic obstructive pulmonary disease or peripheral arterial disease.

RESULTS

A total of 42 studies were included in the overall review, whereas a total of 37 studies were included in the meta-analysis. There was a standardised mean difference (SMD) of - 0.54 (95% CI - 0.70, - 0.37, p = 0.00001) in favour of INT compared to SIT for glucose. With respect to insulin, there was an SMD of - 0.56 (95% CI - 0.74, - 0.38, p = 0.00001) in favour of INT. For TAG, there was an SMD of - 0.26 (95% CI - 0.44, - 0.09, p = 0.002) in favour of INT. Body mass index (BMI) was associated with glucose responses (β = - 0.05, 95% CI - 0.09, - 0.01, p = 0.01), and insulin (β = - 0.05, 95% CI - 0.10, - 0.006, p = 0.03), but not TAG (β = 0.02, 95% CI - 0.02, 0.06, p = 0.37). When energy expenditure was matched, there was an SMD of - 0.26 (95% CI - 0.50, - 0.02, p = 0.03) in favour of INT for glucose, but no statistically significant SMDs for insulin, i.e. 0.35 (95% CI - 0.37, 1.07, p = 0.35), or TAG i.e. 0.08 (95% CI - 0.22, 0.37, p = 0.62). It is worth noting that there was possible publication bias for TAG outcomes when PA breaks were compared with sitting.

CONCLUSION

The use of PA breaks during sitting moderately attenuated post-prandial glucose, insulin, and TAG, with greater glycaemic attenuation in people with higher BMI. There was a statistically significant small advantage for PA breaks over continuous exercise for attenuating glucose measures when exercise protocols were energy matched, but no statistically significant differences for insulin and TAG. PROSPERO Registration: CRD42017080982.

PROSPERO REGISTRATION

CRD42017080982.

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.

Are Patients With Type 2 Diabetes Not Aware or Are They Unable to Practice Self-Care? A Qualitative Study in Rural South India

Background: Lack of awareness and poor adherence to dietary, lifestyle modifications, and medications among patients with diabetes result in poor health outcomes. Aim: This study aimed to understand patients’ perceptions about barriers to self-management of diabetes. Materials and Methods: This was a descriptive qualitative study among patients with diabetes attending a rural health center. Five focus group discussions were conducted with 8 to 11 participants using a topic guide. Results: Many were unaware of target levels and complications of diabetes. Some aspects of the dietary information were found to be quite confusing. Physical constraints prevented many from going for outdoor walking. They have not received any information on foot care. Conclusions: Understanding the barriers for self-care will help health care workers manage diabetes better.

REducing SEDENTary Behavior Among Mild to Moderate Cognitively Impaired Assisted Living Residents: A Pilot Randomized Controlled Trial (RESEDENT Study)

Older adults in assisted living spend most of their day in sedentary behaviors, which may be detrimental to cognitive function. The primary purpose of this pilot study was to assess the feasibility of using a prompting device to reduce sitting time with light walking among older adults with mild to moderate cognitive impairment residing in an assisted living setting. A secondary purpose was to examine the effectiveness of the intervention on the residents' cognitive function, physical function, and quality of life. The participants (n = 25, mean age = 86.7 [5.3] years) were assigned in clusters into a two-arm 10-week single-site pilot randomized controlled trial. The intervention group was prompted with a watch to interrupt sedentary behaviors and partake in 10 min of light physical activity (i.e., walking) three times a day after a meal. The assessments included hip-worn accelerometers (Actical) and diaries, the Alzheimer's disease assessment scale-cognitive, Timed Up and Go, and the short-form 36 health survey. Adherence was high, as there were no dropouts, and over 70% of the participants completed over 80% of the prescribed physical activity bouts. Significant effects favoring the intervention were shown for all outcomes.

Effects of Acute Dietary Polyphenols and Post-Meal Physical Activity on Postprandial Metabolism in Adults with Features of the Metabolic Syndrome

Approximately 22% of U.S. adults and 25% of adults globally have metabolic syndrome (MetS). Key features, such as dysglycemia and dyslipidemia, predict type 2 diabetes, cardiovascular disease, premature disability, and death. Acute supplementation of dietary polyphenols and post-meal physical activity hold promise in improving postprandial dysmetabolism. To our knowledge, no published review has described the effects of either intervention on postprandial glucose, insulin, lipids, and markers of oxidative damage and inflammation in adults with features of MetS. Thus, we conducted this review of controlled clinical trials that provided dietary polyphenols from oils, fruits, teas, and legumes during a dietary challenge, or implemented walking, cycling, and stair climbing and descending after a dietary challenge. Clinical trials were identified using ClinicalTrials.gov, PubMed, and Google Scholar and were published between 2000 and 2019. Dietary polyphenols from extra virgin olive oil, grapes, blackcurrants, strawberries, black tea, and black beans improved postprandial glucose, insulin, and markers of oxidative damage and inflammation, but results were not consistent among clinical trials. Freeze-dried strawberry powder distinctly improved postprandial insulin and markers of oxidative damage and inflammation. Post-meal physical activity attenuated postprandial glucose, but effects on postprandial lipids and markers of oxidative damage and inflammation were inconclusive. Consuming dietary polyphenols with a meal and completing physical activity after a meal may mitigate postprandial dysmetabolism in adults with features of MetS.

Glycemic effect of post-meal walking compared to one prandial insulin injection in type 2 diabetic patients treated with basal insulin: A randomized controlled cross-over study

Studies demonstrate that post-meal walking decreases postprandial hyperglycemia in type 2 diabetic patients but it has never been tested with the active treatment comparator. The objective of this study was to determine the effect of post-meal walking on glycemic control compared with one prandial insulin in type 2 diabetic patients who failed basal insulin. A randomized controlled cross-over study of post-meal walking or one prandial insulin was done in type 2 diabetic patients who were being treated with basal insulin between May 2017 and March 2018. In post-meal walking group, patients walked after meal for 15–20 minutes one meal a day every day for 6 weeks. In prandial insulin (basal plus) group, one prandial insulin was injected before breakfast or main meal with rapid-acting insulin. The primary outcome was a difference in HbA1c reduction in post-meal walking compared with basal plus groups. Fourteen patients completed the study. By intention-to-treat analysis, HbA1c was reduced by -0.05(range:-1.08 to 0.74) and -0.19(range:-0.8 to 0.56) % in post-meal walking and basal plus groups respectively. By per-protocol analysis, post-meal walking and basal plus groups decreased HbA1c by 0.13(range:-0.74 to 1.08) and 0.2(range:-0.56 to 0.8) %, respectively. There was were no significant differences in HbA1c reduction from baseline in each group and between groups in both intention-to-treat and per-protocol analysis. Fructosamine levels were decreased by 17.5(-59 to 43) and 10(-15 to 40) μmol/L, respectively at 3 and 6 weeks in post-meal walking group whereas the respective changes in basal plus group were 12.5(-17 to 64) and 17.5(-28 to 38) μmol/L and there were no significant differences in fructosamine reduction from baseline in each group and between groups. In conclusion, although post-meal walking might be as effective as one prandial insulin to improve glycemic control in type 2 diabetic patients who failed basal insulin but the magnitude of reduction was small. A longer-term study with a larger sample size or with a different walking protocol is required.

Continuous Glucose Monitoring As a Behavior Modification Tool

Real-time continuous glucose monitoring (CGM) use may lead to behavioral modifications in food selection and physical activity, but there are limited data on the utility of CGM in facilitating lifestyle changes. This article describes an 18-item survey developed to explore whether patients currently using CGM believe the technology has caused them to change their behavior.

Using Continuous Glucose Monitoring to Motivate Physical Activity in Overweight and Obese Adults: A Pilot Study

BACKGROUND

Regular physical activity (PA) is associated with a lower risk of several types of cancers. However, two-thirds of overweight/obese adults are not sufficiently active; this, in combination with the unfavorable effect of excess body weight, puts them at a greater risk for cancer. One reason that these individuals do not engage in enough PA may be their lack of motivation to change their current behavior due to the perception of putting in effort for possible future gain without obvious short-term benefits. There is a need for innovative ways to help individuals recognize the immediate health benefits of PA and thus increase their motivation.

METHODS

This pilot intervention tested a PA education module that included a one-on-one counseling session highlighting the acute effects of PA on glucose patterns, followed by a 10-day self-monitoring period with a continuous glucose monitor (CGM) and a Fitbit tracker. Participants rated the acceptability of the education module on a 5-point Likert scale and completed surveys assessing stages of change for motivational readiness.

RESULTS

Nineteen overweight/obese adults (84% female) completed the study. Participants gave high ratings to the counseling session for improving their PA-related knowledge (mean = 4.22), increasing motivation (mean = 4.29), and providing personally relevant information (mean = 4.35). The summary acceptability scores for the self-monitoring period were 4.46 for CGM and 4.51 for Fitbit. Participants reported a significant decrease in the precontemplation stage and an increase in the action stage (P < 0.05).

CONCLUSIONS

CGM is a feasible tool for PA interventions.

IMPACT

Information from CGM could be used as biological-based feedback to motivate PA.See all articles in this CEBP Focus section, "Modernizing Population Science."

Impact of free-living pattern of sedentary behaviour on intra-day glucose regulation in type 2 diabetes

Purpose

To investigate how the pattern of sedentary behaviour affects intra-day glucose regulation in type 2 diabetes.

Methods

This intensive longitudinal study was conducted in 37 participants with type 2 diabetes (age, 62.8 ± 10.5 years). Glucose and sedentary behaviour/physical activity were assessed with a continuous glucose monitoring (Abbott FreeStyle Libre) and an activity monitor (activPAL3) for 14 days. Multiple regression models with generalised estimating equations (GEEs) approach were used to assess the associations of sedentary time and breaks in sedentary time with pre-breakfast glucose, pre-lunch glucose, pre-dinner glucose, post-breakfast glucose, post-lunch glucose, post-dinner glucose, bedtime glucose, the dawn phenomenon, time in target glucose range (TIR, glucose 3.9–10 mmol/L) and time above target glucose range (TAR, glucose > 10 mmol/L).

Results

Sedentary time was associated with higher pre-breakfast glucose (p = 0.001), pre-dinner glucose (p < 0.001), post-lunch glucose (p = 0.005), post-dinner glucose (p = 0.013) and the dawn phenomenon (p < 0.001). Breaks in sedentary time were associated with lower pre-breakfast glucose (p = 0.023), pre-dinner glucose (p = 0.023), post-breakfast glucose (p < 0.001) and the dawn phenomenon (p = 0.004). The association between sedentary time and less TIR (p = 0.022) and the association between breaks in sedentary time and more TIR (p = 0.001) were also observed.

Conclusions

Reducing sedentary time and promoting breaks in sedentary time could be clinically relevant to improve intra-day glucose regulation in type 2 diabetes.

Electronic supplementary material

The online version of this article (10.1007/s00421-019-04261-z) contains supplementary material, which is available to authorized users.

Impact of energy turnover on the regulation of glucose homeostasis in healthy subjects

Objective

Sedentary lifestyle increases the risk of type 2 diabetes. The aim of this study was to investigate the impact of different levels of energy turnover (ET; low, medium, and high level of physical activity and the corresponding energy intake) on glucose metabolism at zero energy balance, caloric restriction, and overfeeding.

Methods

Sixteen healthy individuals (13 men, 3 women, 25.1 ± 3.9 years, BMI 24.0 ± 3.2 kg/m²) participated in a randomized crossover intervention under metabolic ward conditions. Subjects passed 3 × 3 intervention days. Three levels of physical activity (PAL: low 1.3, medium 1.6, and high 1.8 achieved by walking at 4 km/h for 0, 3 × 55, or 3 × 110 min) were compared under three levels of energy balance (zero energy balance (EB): 100% of energy requirement (Ereq); caloric restriction (CR): 75% Ereq, and overfeeding (OF): 125% Ereq). Continuous interstitial glucose monitoring, C-peptide excretion, and HOMA–IR, as well as postprandial glucose and insulin were measured.

Results

Daylong glycemia and insulin secretion did not increase with higher ET at all conditions of energy balance (EB, CR, and OF), despite a correspondingly higher CHO intake (Δ low vs. high ET: +86 to 135 g of CHO/d). At CR, daylong glycemia (p = 0.02) and insulin secretion (p = 0.04) were even reduced with high compared with low ET. HOMA–IR was impaired with OF and improved with CR, whereas ET had no effect on fasting insulin sensitivity. A higher ET led to lower postprandial glucose and insulin levels under conditions of CR and OF.

Conclusion

Low-intensity physical activity can significantly improve postprandial glycemic response of healthy individuals, independent of energy balance.

Minimal effect of walking before dinner on glycemic responses in type 2 diabetes: outcomes from the multi-site E-PAraDiGM study

AIM

To examine the effect of walking before dinner on 24-h glycemic control in individuals with type 2 diabetes using the standardized multi-site Exercise-Physical Activity and Diabetes Glucose Monitoring (E-PAraDiGM) Protocol.

METHODS

Eighty participants were studied under two conditions (exercise vs. non-exercise control) separated by 72 h in a randomized crossover design. Each condition lasted 2 days during which standardized meals were provided. Exercise consisted of 50 min of treadmill walking at 5.0 km/h before the evening meal, while control involved 50 min of sitting. The primary outcome measure was mean glucose during the 24-h period following exercise (or sitting) measured by continuous glucose monitoring.

RESULTS

Of the 80 participants who were initially randomized, 73 completed both exercise and control. Sixty-three participants [29 males, 34 females; age = 64 ± 8 years, body mass index = 30.5 ± 6.5 kg/m² and HbA1c = 51 ± 8 mmol/mol (6.8 ± 0.7%), mean ± SD] complied with the standardized diets and had complete continuous glucose monitoring data. Exercise did not affect mean 24-h glucose compared to control (0.03 mmol/L; 95% CI - 0.17, 0.22, P = 0.778) but individual differences between conditions ranged from - 2.8 to +1.8 mmol/L. Exercise did not affect fasting glucose, postprandial glucose or glucose variability. Glucose concentrations measured by continuous glucose monitoring were reduced during the 50 min of walking in exercise compared to sitting in control (- 1.56 mmol/L; 95% CI - 2.18, - 0.95, p < 0.001).

CONCLUSION

Contrary to previous acute exercise studies, 50 min of walking before dinner in the E-PAraDiGM protocol did not affect 24-h glucose profiles. However, highly heterogeneous responses to exercise were observed.

TRIAL REGISTRATION

NCT02834689.

GC/MS-based metabolomics strategy to analyze the effect of exercise intervention in diabetic rats

Metabolomics was used to explore the effect of exercise intervention on type 2 diabetes. The rat model of type 2 diabetes was induced by an injection of streptozocin (30 mg/kg), after fed with 8-week high-fat diet. The rats were divided into three groups: the control group, the diabetic model group (DM) and the diabetes + exercise group (DME). After exercise for 10 weeks, blood samples were collected to test biomedical indexes, and 24-h urine samples were collected for the metabolomics experiment. In the DME group, fasting blood glucose (FBG), both total cholesterol (TC) and total plasma triglycerides (TG), were decreased significantly, compared with those in the DM group. Based on gas chromatography-mass spectrometry (GC/MS), a urinary metabolomics method was used to study the mechanism of exercise intervention on diabetes mellitus. Based on the principal component analysis (PCA), it was found that the DM group and control group were separated into two different clusters. The DME group was located between the DM group and the control group, closer to the control group. Twelve significantly changed metabolites of diabetes mellitus were detected and identified, including glycolate, 4-methyl phenol, benzoic acid, 1H-indole, arabinitol, threitol, ribonic acid, malic acid, 2,3-dihydroxy-butanoic, aminomalonic acid, l-ascorbic acid and 3-hydroxy hexanedioic acid. After exercise, seven metabolites were significantly changed, compared with the control group, the relative contents of benzoic acid, aminomalonic acid, tetrabutyl alcohol and ribonucleic acid in the diabetic exercise group decreased significantly. The relative contents of 2,3-dihydroxybutyric acid, l-ascorbic acid and 3-hydroxy adipic acid increased significantly. l-ascorbic acid and aminomalonic acid which related with the oxidative stress were significantly regulated to normal. The results showed that exercise could display anti-hyperglycemic and anti-hyperlipidemic effects. The exercise had antioxidation function in preventing the occurrence of complications with diabetes mellitus to some extent. The work illustrates that the metabolomics method is a useful tool to study the mechanism of exercise treatment.

Managing free-living hyperglycemia with exercise or interrupted sitting in type 2 diabetes

Breaking up sitting with light physical activity (PA) is effective in reducing hyperglycemia in the laboratory. Whether the same effects are observed in the free-living environment remains unknown. We evaluated how daily and postprandial glycemia is impacted by 20, 40, or 60 min of activity performed as either breaks from sitting after each meal (BR) or as one continuous walk after breakfast (WALK). Thirty individuals with type 2 diabetes completed three experimental conditions [BR, WALK, and control (CON)] in a randomized crossover design. Conditions were performed in a free-living environment with strict dietary control over 7 days. Participants increased PA in BR and WALK by 20, 40, or 60 min ( n = 10 in each group) and maintained habitual levels of PA during CON. A continuous glucose monitor (iPro2) and activPAL activity monitor were worn to quantify glycemic control and PA. Using linear mixed models with repeated measures, we 1) compared postprandial glucose (PPG) across conditions and 2) assessed the relationship between activity volume and glucose responses. Whereas WALK tended to shorten the daily duration of hyperglycemia compared with CON ( P = 0.0875), BR was not different from CON. BR and WALK significantly attenuated the breakfast PPG versus CON ( P ≤ 0.05), but lunch and dinner PPG were unaffected by BR and WALK. In conclusion, continuous walking was more effective than breaks from sitting in lowering daily hyperglycemia for the group, but both conditions lowered breakfast PPG. In contrast to tightly controlled laboratory studies, breaks from sitting did not lower hyperglycemia in the free-living environment.

NEW & NOTEWORTHY Our “ecolabical” approach is new and noteworthy. This approach combines the external validity of the free-living environment (ecological) with the control of key confounding variables in the laboratory and allows for highly translatable findings by minimizing confounding variables. We found that both postmeal continuous walking and short breaks from sitting similarly attenuated the postprandial glucose (PPG) response to breakfast. Unlike previous laboratory studies, neither condition (walk after breakfast or postmeal breaks) significantly impacted PPG at lunch or dinner.

The effect of a short-term low-carbohydrate, high-fat diet with or without postmeal walks on glycemic control and inflammation in type 2 diabetes: a randomized trial

Lowering carbohydrate consumption effectively lowers glucose, but impacts on inflammation are unclear. The objectives of this study were to: 1) determine whether reducing hyperglycemia by following a low-carbohydrate, high-fat (LC) diet could lower markers of innate immune cell activation in type 2 diabetes (T2D) and 2) examine if the combination of an LC diet with strategically timed postmeal walking was superior to an LC diet alone. Participants with T2D ( n = 11) completed a randomized crossover study involving three 4-day diet interventions: 1) low-fat low-glycemic index (GL), 2) and 3) LC with 15-min postmeal walks (LC+Ex). Four-day mean glucose was significantly lower in the LC+Ex group as compared with LC (-5%, P < 0.05), whereas both LC+Ex (-16%, P < 0.001) and LC (-12%, P < 0.001) conditions were lower than GL. A significant main effect of time was observed for peripheral blood mononuclear cells phosphorylated c-Jun N-terminal kinase ( P < 0.001), with decreases in all three conditions (GL: -32%, LC: -45%, and LC+Ex: -44%). A significant condition by time interaction was observed for monocyte microparticles ( P = 0.040) with a significant decrease in GL (-76%, P = 0.035) and a tendency for a reduction in LC (-70%, P = 0.064), whereas there was no significant change in LC+Ex (0.5%, P = 0.990). Both LC (-27%, P = 0.001) and LC+Ex (-35%, P = 0.005) also led to significant reductions in circulating proinsulin. An LC diet improved 4-day glycemic control and fasting proinsulin levels when compared with GL, with added glucose-lowering benefits when LC was combined with postmeal walking.

The Timing of Activity after Eating Affects the Glycaemic Response of Healthy Adults: A Randomised Controlled Trial

There is scant information on how a time lag between the cessation of eating and commencement of physical activity affects postprandial glycaemia. Starting at baseline (t = 0), participants ingested white bread containing 50 g of available carbohydrates within 10 min. Using two crossover conditions, we tested the effect over 2 h on postprandial glycaemia of participants undertaking light activity at 15 or 45 min following baseline and compared it with a sedentary control condition. The activity involved cycling on a stationary ergometer for 10 min at 40 revolutions per min with zero resistance. Seventy-eight healthy adults were randomized to the 15 or 45 min activity arm and then randomised to the order in which they undertook the active and sedentary conditions. Cycling 45 min after baseline changed the course of the blood glucose response (likelihood ratio chi square = 31.47, p < 0.01) and reduced mean blood glucose by 0.44 mmol/L (95% confidence interval 0.14 to 0.74) at 60 min when compared with the sedentary control. No differences in postprandial blood glucose response were observed when cycling started 15 min after baseline compared with the sedentary control. Undertaking activity after waiting for 30 min following eating might be optimal in modifying the glycaemic response.

Acceptability of Continuous Glucose Monitoring in Free-Living Healthy Individuals: Implications for the Use of Wearable Biosensors in Diet and Physical Activity Research

BACKGROUND

Wearable sensors have been increasingly used in behavioral research for real-time assessment and intervention purposes. The rapid advancement of biomedical technology typically used in clinical settings has made wearable sensors more accessible to a wider population. Yet the acceptability of this technology for nonclinical purposes has not been examined.

OBJECTIVE

The aim was to assess the acceptability of wearing a continuous glucose monitor (CGM) device among a sample of nondiabetic individuals, and to compare the acceptability of a CGM between a mobile diet tracking app (MyFitnessPal) and an accelerometer.

METHODS

A total of 30 nondiabetic adults went through a 7-day observational study. They wore a CGM sensor, tracked their diet and physical activity using the CGM receiver and MyFitnessPal, and wore an accelerometer on their waist. After the monitoring period, they completed a 10-item survey regarding acceptability of each of the study tools. Two-tailed paired-sample t tests were conducted to examine whether the summary acceptability scores were comparable between the CGM sensor/receiver and MyFitnessPal/accelerometer.

RESULTS

More than 90% of the study participants agreed that the CGM sensor and receiver were easy to use (28/30 and 27/30, respectively), useful (28/30 and 29/30, respectively), and provided relevant information that was of interest to them (27/30 and 28/30, respectively). The summary acceptability scores (out of a 5-point Likert scale) were mean 4.06 (SD 0.55) for the CGM sensor, mean 4.05 (SD 0.58) for the CGM receiver, mean 4.10 (SD 0.68) for MyFitnessPal, and mean 3.73 (SD 0.76) for the accelerometer.

CONCLUSIONS

The high acceptability of using a CGM from this study suggests a great potential for using CGMs in nondiabetic adults in research settings. Although potential selection bias might contribute to the high acceptability in this study, the continued advancements in wearable sensor technology will make the barriers to tracking and collecting personal physiological data more and more minimal.