Carbohydrate Intake in the Context of Exercise in People with Type 1 Diabetes

The effect of physical activity on cytokine levels in adults living with type 1 diabetes-a preliminary study

The aim of this study is to investigate whether physical activity and the level of body fat are factors reducing the level of pro-inflammatory cytokines in people with T1DM. Twenty-five men (27.8 ± 9.4 years old; 178.9 ± 6.9 cm; 80.6 ± 12 kg) and 18 women (28.1 ± 12.5 years old; 162.4 ± 5.5; 63.1 ± 9.9 kg) were divided into four groups based on body fat percentage and level of physical activity (AN-active people with normal body fat; IAN-inactive people with normal body fat; AO-active people with excessive body fat, IAO-inactive people with excessive body fat). The level of cytokines in the blood serum was assessed. The level of IL-8 was higher (measurable) in inactive men, regardless of adiposity degree and in women, only in the inactive group with normal body fat. IL-6 was found only in active men with excessive adiposity. In conclusion, the findings from this study allow to indicate that moderate level of physical activity may contribute to a reduction in the development of systemic low-grade inflammation in patients with T1DM, and thus, may reduce the risk of CVD.

Recovery Phase Nutrition and Insulin Strategies for a Collegiate Distance Runner with Type 1 Diabetes Mellitus: A Case Study

PURPOSE

There is scant published research regarding nutrition and insulin strategies for athletic performance in collegiate distance runners with type 1 diabetes mellitus (CDRT1). Acute carbohydrate supplementation (CHOsup) and insulin reduction used to minimize hypoglycemia during exercise may result in deteriorated glycemic control post exercise in CDRT1. The present case study of a CDRT1 investigated outcomes associated with a moderate-carbohydrate (ModCHO) diet and 24 h insulin adjustment during recovery phases for improved glycemic control and reduced use of acute strategies.

METHODS

During an 8-day period, a female CDRT1 followed a ModCHO (~4 g/kg/day) nutrition program. Recovery phase adjustments to insulin doses were made using an equation developed to estimate reduced insulin needs post exercise, as a function of exercise intensity and duration. Daily training was performed in the fasted state at 6:00 a.m. and included additional exercise strategies to reduce glycemic variability when needed. Daily blood glucose time-in-range (TIR) and use of CHOsup were assessed. Athlete well-being was determined using the Student-Athlete Well-Being Scale (SAWS)TM at baseline, and days 1, 3, and 7.

RESULTS

Throughout the 8-day period, mean TIR increased (77% versus < 50%) and the magnitude of glycemic excursions decreased (~3.8-15 versus ~3.0-26 mmol/L) relative to a prior comparison period. Minimal pre-exercise CHOsup was employed and CHOsup during exercise was not required. Additionally, the athlete achieved a new lifetime best in the 5000 m run and maintained positive well-being.

CONCLUSION

The present case study provides examples of recovery phase strategies (i.e., ModCHO diet and 24 h insulin adjustments) that may support glycemic control and athletic performance in CDRT1 and provides potential considerations for nutrition and insulin strategies for use by athletes and coaches.

Effects of postprandial exercise on blood glucose levels in adults with type 1 diabetes: a review

People with type 1 diabetes experience challenges in managing blood glucose around exercise. Previous studies have examined glycaemic responses to different exercise modalities but paid little attention to participants' prandial state, although this is an important consideration and will enhance our understanding of the effects of exercise in order to improve blood glucose management around activity. This review summarises available data on the glycaemic effects of postprandial exercise (i.e. exercise within 2 h after a meal) in people with type 1 diabetes. Using a search strategy on electronic databases, literature was screened until November 2022 to identify clinical trials evaluating acute (during exercise), subacute (≤2 h after exercise) and late (>2 h to ≤24 h after exercise) effects of postprandial exercise in adults with type 1 diabetes. Studies were systematically organised and assessed by exercise modality: (1) walking exercise (WALK); (2) continuous exercise of moderate intensity (CONT MOD); (3) continuous exercise of high intensity (CONT HIGH); and (4) interval training (intermittent high-intensity exercise [IHE] or high-intensity interval training [HIIT]). Primary outcomes were blood glucose change and hypoglycaemia occurrence during and after exercise. All study details and results per outcome were listed in an evidence table. Twenty eligible articles were included: two included WALK sessions, eight included CONT MOD, seven included CONT HIGH, three included IHE and two included HIIT. All exercise modalities caused consistent acute glycaemic declines, with the largest effect size for CONT HIGH and the smallest for HIIT, depending on the duration and intensity of the exercise bout. Pre-exercise mealtime insulin reductions created higher starting blood glucose levels, thereby protecting against hypoglycaemia, in spite of similar declines in blood glucose during activity between the different insulin reduction strategies. Nocturnal hypoglycaemia occurred after higher intensity postprandial exercise, a risk that could be diminished by a post-exercise snack with concomitant bolus insulin reduction. Research on the optimal timing of postprandial exercise is inconclusive. In summary, individuals with type 1 diabetes exercising postprandially should substantially reduce insulin with the pre-exercise meal to avoid exercise-induced hypoglycaemia, with the magnitude of the reduction depending on the exercise duration and intensity. Importantly, pre-exercise blood glucose and timing of exercise should be considered to avoid hyperglycaemia around exercise. To protect against late-onset hypoglycaemia, a post-exercise meal with insulin adjustments might be advisable, especially for exercise in the evening or with a high-intensity component.

Where to Start? Physical Assessment, Readiness, and Exercise Recommendations for People With Type 1 or Type 2 Diabetes

Exercise plays an important role in the management of diabetes and is associated with many benefits such as decreased morbidity and mortality. For people exhibiting signs and symptoms of cardiovascular disease, pre-exercise medical clearance is warranted; however, requiring broad screening requirements can lead to unnecessary barriers to initiating an exercise program. Robust evidence supports the promotion of both aerobic and resistance training, with evidence emerging on the importance of reducing sedentary time. For people with type 1 diabetes, there are special considerations, including hypoglycemia risk and prevention, exercise timing (including prandial status), and differences in glycemic responses based on biological sex.

Are nocturnal hypoglycemia prevention strategies influenced by diabetes technology usage? A BETTER registry analysis

AIM

To assess the association of nocturnal hypoglycemia prevention strategies (NH-PS) and diabetes technology usage (insulin pump and/or continuous glucose monitors [CGM]) in people with type 1 diabetes (PWT1D).

METHODS

Logistic regression models were used to describe associations between self-reported NH-PS and diabetes technology (pump with intermittently-scanned or real-time CGM (isCGM or rtCGM), or automated insulin delivery (AID)), hypoglycemia history, and fear of hypoglycemia (FOH).

RESULTS

Among 831 adults (65 % female, aged 44 ± 15 years, T1D duration 26 ± 15 years), 32 % reported HbA1c ≤ 7.0 %, 88 % used ≥ 1 diabetes technology, 66 % reported ≥ 1 symptomatic NH in the past month, and 64 % used ≥ 2 NH-PS. Compared to multiple daily injections (MDI) + capillary blood glucose (CBG), bedtime snack consumption was less likely among pump + isCGM (OR [95 %CI]: 0.55 [0.31, 0.98]), pump + rtCGM (0.40 [0.20, 0.81]), and AID (0.34 [0.17, 0.66]) users, while evening insulin basal reduction was associated with CSII + CBG (3.15 [1.25, 7.99]), pump + isCGM 4.00 [1.99, 8.01]), and pump + rtCGM 2.89 [1.28, 6.50] use. Elevated FOH was associated with snack consumption (1.37 [1.00, 1.89]), evening bolus insulin avoidance (1.77 [1.11, 2.83]), limiting exercise (2.50 [1.30, 4.82]), and limiting alcohol consumption (2.33 [1.15, 4.70]) as NH-PS.

CONCLUSION

Technology use and elevated FOH might influence PWT1D' choice of NH-PS.

New Horizons in Carbohydrate Research and Application for Endurance Athletes

The importance of carbohydrate as a fuel source for exercise and athletic performance is well established. Equally well developed are dietary carbohydrate intake guidelines for endurance athletes seeking to optimize their performance. This narrative review provides a contemporary perspective on research into the role of, and application of, carbohydrate in the diet of endurance athletes. The review discusses how recommendations could become increasingly refined and what future research would further our understanding of how to optimize dietary carbohydrate intake to positively impact endurance performance. High carbohydrate availability for prolonged intense exercise and competition performance remains a priority. Recent advances have been made on the recommended type and quantity of carbohydrates to be ingested before, during and after intense exercise bouts. Whilst reducing carbohydrate availability around selected exercise bouts to augment metabolic adaptations to training is now widely recommended, a contemporary view of the so-called train-low approach based on the totality of the current evidence suggests limited utility for enhancing performance benefits from training. Nonetheless, such studies have focused importance on periodizing carbohydrate intake based on, among other factors, the goal and demand of training or competition. This calls for a much more personalized approach to carbohydrate recommendations that could be further supported through future research and technological innovation (e.g., continuous glucose monitoring). Despite more than a century of investigations into carbohydrate nutrition, exercise metabolism and endurance performance, there are numerous new important discoveries, both from an applied and mechanistic perspective, on the horizon.

Characterization of Individualized Glycemic Excursions during a Standardized Bout of Hypoglycemia-Inducing Exercise and Subsequent Hypoglycemia Treatment-A Pilot Study

The glycemic response to ingested glucose for the treatment of hypoglycemia following exercise in type 1 diabetes patients has never been studied. Therefore, we aimed to characterize glucose dynamics during a standardized bout of hypoglycemia-inducing exercise and the subsequent hypoglycemia treatment with the oral ingestion of glucose. Ten male patients with type 1 diabetes performed a standardized bout of cycling exercise using an electrically braked ergometer at a target heart rate (THR) of 50% of the individual heart rate reserve, determined using the Karvonen equation. Exercise was terminated when hypoglycemia was reached, followed by immediate hypoglycemia treatment with the oral ingestion of 20 g of glucose. Arterialized blood glucose (ABG) levels were monitored at 5 min intervals during exercise and for 60 min during recovery. During exercise, ABG decreased at a mean rate of 0.11 ± 0.03 mmol/L·min⁻¹ (minimum: 0.07, maximum: 0.17 mmol/L·min⁻¹). During recovery, ABG increased at a mean rate of 0.13 ± 0.05 mmol/L·min⁻¹ (minimum: 0.06, maximum: 0.19 mmol/L·min⁻¹). Moreover, 20 g of glucose maintained recovery from hypoglycemia throughout the 60 min postexercise observation window.

The Association between Daily Total Dietary Nutrient Intake and Recent Glycemic Control States of Non-Pregnant Adults 20+ Years Old from NHANES 1999-2018 (Except for 2003-2004)

Background: Although daily total dietary nutrient intakes were potentially important factors in maintaining glycemic balance, their overall effect on glycemic control was still unclear among American adults. Objectives: We aimed to examine the association between daily total dietary nutrient intake and recent glycemic control status (RGCS). Methods: This cohort was composed of 41,302 individuals from the National Health and Nutrition Examination Survey (NHANES). The daily total intake of dietary nutrients and RGCS were independent and dependent variables, respectively. To evaluate their association, we carried out binary logistic regression, model fitting, linear discriminant analysis, and the receiver operator characteristic (ROC) analysis. Results: The result of robust check model showed that only the daily total dietary vitamin B6 intake (adjusted OR = 0.848; 95% CI: 0.738, 0.973; p-value = 0.019) was significantly negatively correlated with RGCS. When daily total dietary vitamin B6 intake and glycosylated hemoglobin (HbA1c) were used as independent variables and dependent variables, respectively, to fit the curves and lines, the established robust check model could distinguish American adults with different RGCS well. Moreover, the robust check model results of ROC analysis indicated that daily total dietary vitamin B6 intake might be a potential predictor for RGCS (AUC = 0.977; 95% CI: 0.974, 0.980; p-value < 0.001). Conclusions: This study showed that only daily total dietary vitamin B6 intake was a beneficial factor in RGCS, but it might need further multicenter or prospective studies to verify whether vitamin B6 had biological implications and public health meaning for glycemic control among American adults (specifically referred to non-pregnant participants over 20 years old).

Physical Activity, Dietary Patterns, and Glycemic Management in Active Individuals with Type 1 Diabetes: An Online Survey

Individuals with type 1 diabetes (T1D) are able to balance their blood glucose levels while engaging in a wide variety of physical activities and sports. However, insulin use forces them to contend with many daily training and performance challenges involved with fine-tuning medication dosing, physical activity levels, and dietary patterns to optimize their participation and performance. The aim of this study was to ascertain which variables related to the diabetes management of physically active individuals with T1D have the greatest impact on overall blood glucose levels (reported as A1C) in a real-world setting. A total of 220 individuals with T1D completed an online survey to self-report information about their glycemic management, physical activity patterns, carbohydrate and dietary intake, use of diabetes technologies, and other variables that impact diabetes management and health. In analyzing many variables affecting glycemic management, the primary significant finding was that A1C values in lower, recommended ranges (<7%) were significantly predicted by a very-low carbohydrate intake dietary pattern, whereas the use of continuous glucose monitoring (CGM) devices had the greatest predictive ability when A1C was above recommended (≥7%). Various aspects of physical activity participation (including type, weekly time, frequency, and intensity) were not significantly associated with A1C for participants in this survey. In conclusion, when individuals with T1D are already physically active, dietary changes and more frequent monitoring of glucose may be most capable of further enhancing glycemic management.

Post-exercise recovery for the endurance athlete with type 1 diabetes: a consensus statement

There has been substantial progress in the knowledge of exercise and type 1 diabetes, with the development of guidelines for optimal glucose management. In addition, an increasing number of people living with type 1 diabetes are pushing their physical limits to compete at the highest level of sport. However, the post-exercise recovery routine, particularly with a focus on sporting performance, has received little attention within the scientific literature, with most of the focus being placed on insulin or nutritional adaptations to manage glycaemia before and during the exercise bout. The post-exercise recovery period presents an opportunity for maximising training adaption and recovery, and the clinical management of glycaemia through the rest of the day and overnight. The absence of clear guidance for the post-exercise period means that people with type 1 diabetes should either develop their own recovery strategies on the basis of individual trial and error, or adhere to guidelines that have been developed for people without diabetes. This Review provides an up-to-date consensus on post-exercise recovery and glucose management for individuals living with type 1 diabetes. We aim to: (1) outline the principles and time course of post-exercise recovery, highlighting the implications and challenges for endurance athletes living with type 1 diabetes; (2) provide an overview of potential strategies for post-exercise recovery that could be used by athletes with type 1 diabetes to optimise recovery and adaptation, alongside improved glycaemic monitoring and management; and (3) highlight the potential for technology to ease the burden of managing glycaemia in the post-exercise recovery period.

Impact of lockdown for COVID-19 pandemic in Indian children and youth with type 1 diabetes from different socio-economic classes

OBJECTIVES

In March 2020, lockdown was imposed in India to combat spread of Coronavirus, which was extended till 31st May. Implementation of lockdown and limited outdoor activities resulted in changes in routines of children with diabetes. The aim of this study was to assess the impact of lockdown on glycemic control, weight and body mass index (BMI) patterns of children with type 1 diabetes (T1DM) from different socio-economic (SE) classes.

METHODS

This observational study included 77 children and youth (5-20 years) with T1DM having disease duration of ≥6 months. Demographic data and investigations were recorded at two time points (post lockdown when the children came for follow up, pre lockdown data from medical records).

RESULTS

Glycemic control improved (pre lockdown HbA1C 79.4±19.2 vs. post lockdown Hba1C 74.5±16.9 mmol/mol, p<0.05) and there was weight gain post lockdown (pre lockdown weight z-score -0.4±0.8 vs. post lockdown weight z-score -0.2±0.8, p<0.05) without any significant change in BMI and insulin requirements. Improved glycemic was seen in the lower SE group control post lockdown (p<0.05), whereas in higher SE group, it remained unchanged. Children whose parents were at home during lockdown showed an improved glycemic control (p<0.05) as compared to children whose parents continued to work during lockdown (p>0.01).

CONCLUSIONS

During coronavirus lockdown, glycemic control was adequately maintained in children with T1DM, highlighting importance of stronger family support system leading to more steady daily routine.

Time spent in hypoglycemia is comparable when the same amount of exercise is performed 5 or 2 days weekly: a randomized crossover study in people with type 1 diabetes

INTRODUCTION

People with type 1 diabetes are recommended to exercise regularly. However, limited evidence exists on how frequency and duration of exercise affect the risk of hypoglycemia. The study aimed to compare the percentage of time spent in hypoglycemia between two 5-day periods with different frequency and duration of physical activity.

RESEARCH DESIGN AND METHODS

In this outpatient randomized crossover study, 26 participants aged 18-65 years with type 1 diabetes for ≥2 years and insulin pump use for ≥1 year were included. After a 7-day observation period, participants completed two 5-day intervention periods separated by a washout period of at least 14 days. One period included five exercise sessions on 5 consecutive days (5S), each consisting of 4 min of resistance training and 30 min of aerobic exercise. Another period included two exercise sessions on 2 days with at least 2 days in between (2S), each consisting of 10 min of resistance training and 75 min of aerobic exercise. During each period, participants performed in total 150 min of aerobic exercise and 20 min of resistance training and wore continuous glucose monitors (Dexcom G6) and accelerometers (ActiGraph wGT3X-BT).

RESULTS

Twenty insulin pump-treated adults (10 women) with type 1 diabetes completed the study. The baseline median (range) age was 48 (24-64) years, glycated hemoglobin 55 (44-66) mmol/mol, diabetes duration 24 (8-57) years, and body mass index 28.4 (22.3-35.8) kg/m². No differences were observed between 5S and 2S in the percentage (mean±SD) of time spent below 3.9 mmol/L (3.5%±2.8% vs 4.5%±4.2%, p=0.28), time spent in 3.9-10.0 mmol/L (65.3%±15.0% vs 68.5%±13.6%, p=0.31), time spent above 10.0 mmol/L (31.2%±16.4% vs 27.3%±14.5%, p=0.15), mean glucose (8.7±1.3 mmol/L vs 8.5±1.2 mmol/L, p=0.33) and glycemic variability (35.8%±5.3% vs 35.8%±6.6%, p=0.97).

CONCLUSIONS

Time spent in hypoglycemia was comparable between the two 5-day periods with different duration and frequency of physical activity.

TRIAL REGISTRATION NUMBER

NCT04089462.

Carbohydrate supplementation: a critical review of recent innovations

PURPOSE

To critically examine the research on novel supplements and strategies designed to enhance carbohydrate delivery and/or availability.

METHODS

Narrative review.

RESULTS

Available data would suggest that there are varying levels of effectiveness based on the supplement/supplementation strategy in question and mechanism of action. Novel carbohydrate supplements including multiple transportable carbohydrate (MTC), modified carbohydrate (MC), and hydrogels (HGEL) have been generally effective at modifying gastric emptying and/or intestinal absorption. Moreover, these effects often correlate with altered fuel utilization patterns and/or glycogen storage. Nevertheless, performance effects differ widely based on supplement and study design. MTC consistently enhances performance, but the magnitude of the effect is yet to be fully elucidated. MC and HGEL seem unlikely to be beneficial when compared to supplementation strategies that align with current sport nutrition recommendations. Combining carbohydrate with other ergogenic substances may, in some cases, result in additive or synergistic effects on metabolism and/or performance; however, data are often lacking and results vary based on the quantity, timing, and inter-individual responses to different treatments. Altering dietary carbohydrate intake likely influences absorption, oxidation, and and/or storage of acutely ingested carbohydrate, but how this affects the ergogenicity of carbohydrate is still mostly unknown.

CONCLUSIONS

In conclusion, novel carbohydrate supplements and strategies alter carbohydrate delivery through various mechanisms. However, more research is needed to determine if/when interventions are ergogenic based on different contexts, populations, and applications.