To Örebro University

OBJECTIVE: The study aimed to investigate the impact of nutrient timing in relation to evening exercise. Specifically, it examined the effects of pre- or post-exercise carbohydrate (CHO) ingestion on glucose metabolism, glucose regulation, and overall substrate oxidation in well-trained athletes during and after physical exercise (PE), spanning the nocturnal period and the subsequent morning.

METHODS: Ten male endurance cyclists participated in the study. The initial assessments included body composition measurements and an incremental cycle test to determine maximal oxygen uptake (V˙O2 max) and maximum power output (Wmax). Following this, participants underwent a control (rest previous day) oral glucose tolerance test (OGTT) and a familiarization exercise trial that had two objectives: (1) to establish the appropriate amount of CHO to use in the pre- or post-exercise drink during the experimental trials, and (2) to familiarize participants with the equipment and study protocol. In the three days prior to both the control and experimental trials, participants followed a standardized, individualized diet designed to meet their energy needs. During the experimental trials, participants completed two separate evening exercise sessions (50 min@70%Wmax +  ~24 min time-trial (TT)) with either pre- or post-exercise CHO ingestion (253 ± 52 g), matching the CHO oxidized during exercise. The CHO drink and a volume-matched placebo (PLA) drink (containing no energy) were randomly assigned to be consumed two hours before and directly after the experimental exercise sessions. Post-exercise nocturnal interstitial glucose levels (24:00-06:00) were continuously monitored, and a 120-min OGTT was conducted the following morning to assess substrate oxidation rates and glucose control.

RESULTS: Pre-exercise CHO intake significantly lowered capillary glucose levels during steady-state exercise (mean difference 0.41 ± 0.27 mmol/L, p = 0.001) without affecting perceived exertion and TT-performance. No difference was observed in nocturnal glucose regulation (00:00-06:00) regardless of whether CHO was consumed before or after exercise. Post-exercise CHO ingestion reduced glucose tolerance during the OGTT compared to the iso-caloric pre-exercise CHO intake (mean difference 0.76 ± 0.21 mmol/L, p = 0.017). However, a post-exercise CHO intake improved respiratory exchange ratio/metabolic flexibility (MetF) significantly. Enhanced MetF during the first OGTT hour after post-exercise CHO ingestion resulted in 70% and 91% higher CHO oxidation compared to pre-exercise CHO and control, respectively (p ≤ 0.029). Average 120-min OGTT fat oxidation rates were higher with both pre- and post-exercise CHO ingestion compared to control (p ≤ 0.008), with no difference between pre- and post-exercise CHO intake.

CONCLUSION: Morning glucose tolerance was markedly reduced in healthy athletes when CHO was ingested after evening exercise. However, the observed improvements in MetF during the OGTT compared to placebo post-exercise suggest a potential for enhanced athletic performance in subsequent exercise sessions. This opens exciting possibilities for future research to explore whether enhanced MetF induced by CHO-timing can translate to improved athletic performance, offering new avenues for optimizing training and performance.

Background: Physical exercise (PE) represents a challenge in achieving stable glycemic control in individuals with type 1 diabetes (T1D), especially during prolonged PE. Achieving euglycemia requires careful adjustments of carbohydrate (CHO) intake and insulin doses before, during, and after PE, by proactive use of continuous glucose monitoring (CGM).

Aim: This thesis evaluated strategies for achieving glucose control in T1D before, during, and after prolonged PE, focusing on CHO intake, insulin adjustments assisted by CGM, and education intended to improve self-management.

Methods: Four studies were conducted: (1) High CHO intake with insulin adjustments during prolonged PE; (2) CHO loading, tailored pre-race insulin dose, and high CHO intake during PE; (3) CHO replenishment after evening exercise on nocturnal glucose regulation in healthy individuals; and (4) impact of a diabetes sports camp for adults integrating education and exercise and long-term self-management.

Results: Before PE: CHO loading with basal insulin adjustment maintained stable glycemia. Tailored pre-race insulin supported euglycemia. During PE: High CHO intake (75–100 g/h) with individualized insulin strategies enabled stable glucose levels. After PE: The timing of CHO intake did not affect nocturnal glucose levels when daily energy and CHO needs were met. Self-management: The diabetes sports camp was associated with improvements in perceived diabetes self-management skills.

Conclusion: Glycemic stability in T1D before, during, and after prolonged PE is achievable through individualized CHO and insulin strategies, supported by CGM and structured education.

Aims: To describe the experiences of individuals with diabetes type 1 (T1D) participating in diabetes sports camps and how acquired knowledge could be used in daily self-management.

Methods: Semi-structured telephone interviews were conducted with 15 adults with T1D. A strategic sample procedure was chosen. The interviews were analyzed using qualitative content analysis.

Results: The overarching theme ”Empowered by intertwined theory and practice”, included three main categories: Learning in a motivation-enhancing environment, incorporation of new habits and perceptions of glycemic control and health-related outcomes. The participants considered the camp to be an excellent opportunity to share feelings, ideas, and knowledge. They felt empowered by the camp atmosphere as well as supportive environment. After the camp, the general well-being was improved by incorporating new habits and improvements in glucose control.

Conclusions: A diabetes sports camp constitutes an excellent, but resource-intensive, complimentary support in diabetes care and provides opportunities for T1D individuals to become more independent and autonomous. The findings indicate the need for more directed learning activities for individuals with type 1 diabetes and health care providers to increase their competence in the area of T1D and exercise in order to adequately manage counseling in various types of sports.

Background: Prolonged physical exercise (PE) is a challenge in type 1 diabetes with an increased incidence of both hypoglycemia and hyperglycemia.

Purpose: To evaluate the impact of two consecutive days of carbohydrate (CHO) loading, followed by high intermittent CHO-intake during prolonged PE, facilitated by a proactive use of Real-Time Continuous Glucose Monitoring (rtCGM), on glucose control in individuals with type 1 diabetes.

Methods: Ten physically active individuals with type 1 diabetes were invited to participate in a 3-day long sports camp with the objective to evaluate CHO-loading and high intermittent CHO-intake during prolonged PE. 1.5 months later the same procedure was evaluated in relation to a 90 km cross-country skiing race (Vasaloppet). Participants were instructed to act proactively using rtCGM with predictive alerts to maintain sensor glucose values within target range, defined as 72-180 mg/dl (4-10 mmol/l).

Results: Mean glucose values during CHO-loading were: day 1; 140.4 +/- 45.0 mg/dl (7.8 +/- 2.5 mmol/l) and day 2; 120.6 +/- 41.4 mg/dl (6.7 +/- 2.3 mmol/l). Mean sensor glucose at start of PE was 126.0 +/- 25.2 mg/dl (7.0 +/- 1.4 mmol/l) and throughout PE 127.8 +/- 25.2 mg/dl (7.1 +/- 1.4 mmol/l). Percentage of time spent in range (TIR) respective time spent in hypoglycemia was: CHO-loading 74.7/10.4% and during PE 94.3/0.6%.

Conclusions: High intermittent CHO-intake during prolonged PE combined with proactive use of rtCGM is associated with good glycemic control during prolonged exercise in individuals with diabetes type 1. However, the time spent in hypoglycemia during the 2-days of CHO-loading was 10.4% and therefore a lower insulin dose might be suggested to reduce the time spent in hypoglycemia.

This study investigated the energy, macronutrient, and fluid intakes, as well as hydration status (urine specific gravity), in elite cross-country skiers during a typical day of training (Day 1) and a sprint skiing competition the following day (Day 2). A total of 31 (18 males and 13 females) national team skiers recorded their food and fluid intakes and urine specific gravity was measured on Days 1 and 2. In addition, the females completed the Low Energy Availability in Females Questionnaire to assess their risk of long-term energy deficiency. Energy intake for males was 65 +/- 9 kcal/kg on Day 1 versus 58 +/- 9 kcal/kg on Day 2 (p = .002) and for females was 57 +/- 10 on Day 1 versus 55 +/- 5 kcal/kg on Day 2 (p = .445). Carbohydrate intake recommendations of 10-12 g.kg(-l) .day(-1) were not met by 89% of males and 92% of females. All males and females had a protein intake above the recommended 1.2-2.0 g/kg on both days and a postexercise protein intake above the recommended 0.3 g/kg. Of the females, 31% were classified as being at risk of long-term energy deficiency. In the morning of Day 1, 50% of males and 46% of females were dehydrated; on Day 2, this was the case for 56% of males and 38% of females. In conclusion, these data suggest that elite cross-country skiers ingested more protein and less carbohydrate than recommended and one third of the females were considered at risk of long-term energy deficiency. Furthermore, many of the athletes were dehydrated prior to training and competition.

Purpose: To evaluate the effect of a novel sports camp containing education and individualized feedback, on glycemic control and self-estimated level of knowledge in individuals with type 1 diabetes (T1DM).

Method: Participants with T1DM attended a three-day sports camp with education and individualized feedback on insulin and carbohydrate adjustments. Continuous Glucose Monitoring (CGM) and carbohydrate counting was used. A1c was assessed at baseline, 3 and 12 months after the sports camps. Questionnaires using Visual Analogue Scale (VAS) were used before and after the camp to estimate attitudes and knowledge regarding insulin and carbohydrate adjustments in relation to exercise.

Results: During eight sports camps 105 TIDM participants were included, 53% females, mean age 40.5 ± 10.0 years.

A1c was significantly reduced from 7.5 ± 3.0% (58.7 ± 9.2 mmol/mol) at baseline to 7.3 ± 2.9% (56.2 ± 8.1 mmol/mol), P<.005, after 3 months and maintained after 12 months 7.3 ± 2.9% (56.4 ± 8.1 mmol/mol), P<.005. Self-estimated level of knowledge was significantly improved in the area of insulin adjustments, P<.001 and carbohydrate intake, P<.001, in connection to exercise.

99% of the participants wanted to continue on CGM and 85% of the participants stated they would like to continue with carbohydrate counting after the sports camp.

Conclusion: Sports camps for adults with T1DM, was associated with improved glycemic control and increased self-estimated knowledge regarding insulin and carbohydrate adjustments in relation to exercise. This improvement in A1c, might be linked to the participants’ increased level of knowledge but also to increased use of CGM and carbohydrate counting.

Abbreviations: A1c: Glycated Hemoglobin; BG: Blood Glucose; BMI: Body Mass Index; CGM: Continuous Glucose Monitoring; CHO: Carbohydrates; CSII: Continuous Subcutaneous Insulin Infusion; DSME: Diabetes Self-Management Education; IFCC: International Federation of Clinical Chemistry; IG: Interstitial Glucose; MDI: Multiple Daily Injections; NGSP: National Glycohemoglobin Standardization Program; PG: Plasma Glucose; PE: Physical Exercise; RPE: Rate of Perceived Exertion; SMBG: Self-Monitoring of Blood Glucose; T1DM: Type 1 Diabetes; VAS: Visual Analogue Scale.

Background: Physical activity is advocated in all individuals with diabetes. However, good glycemic control can be difficult to achieve due to exercise induced glucose excursions.

Objective: To evaluate the impact on glucose control of a structured diabetes education concerning physical activity, delivered via the web/internet together with telemedical care (individualized feedback by phone).

Methods: Eighty-two individuals with type 1 (T1D) were included in the pre-race intervention and randomized into two groups: intervention (I) (n=48) and control (C) (n=48). Both groups received web-based training of sports and nutrition in relation to diabetes. The intervention group also received structured and individualized feedback on two different occasions. HbA1c was measured at baseline, after 3 and 6 months when a 45 km cross-country skiing race (the HalvVasa) was performed. Only the individuals attending the skiing race were eligible to be included in the study. Level of Physical Activity (LPA), Multidimensional Health Locus of Control (MHLC) and Confidence In Diabetes Self-care (CIDS) were assessed at baseline and after 7 months.

Results: HbA1c at start was 58.5 ± 10.0 (I) respectively 60.7 ± 9.5 (C) mmol/mol. At 3 months 56.7 ± 8.7 (I) respectively 61.0 ± 9.6 (C) mmol/mol and at 6 months 55.7 ± 8.1 (I) respectively 60.3 ± 9.7 (C) mmol/mol. A significant in (I) at 3 months: 2.2 ± 3.8 mmol/mol (0.7-3.7, 95% CI), (p<0.05) and after 6 months: 2.8 ± 5.5 mmol/mol (0.5-5.0, 95% CI), (p<0.05). No reduction was seen in (C). However between the two groups no difference was noted. The LPA was increased in 52% of the participants in (I) respectively 7% in (C), a significant difference, p<0.05. No differences were seen regarding HbA1c or LPA in the control group.

Conclusion: Education and individualized feedback, delivered via telemedicine, to physical active individuals with T1D resulted in improvements in glycemic control within the intervention group and improved level of physical activity and locus of control when compared to the control group(12) (PDF) Education and individualized support regarding exercise and diabetes improves glucose control and level of physical activity in type 1 diabetes individuals.

Purpose: In healthy individuals, high carbohydrate intake is recommended during prolonged exercise for maximum performance. In type 1 diabetes (T1D), this would alter the insulin requirements. The aim of the study was to evaluate the safety of high glucose supplementation during prolonged exercise and the glucose control when a novel strategy of increased carbohydrate supply was implemented during prolonged exercise in T1D.

Methods: Eight subjects with T1D participated in a sports camp including sessions of prolonged exercise and individualized feedback during three consecutive days. This was later followed by a 90 km cross-country skiing race. Large amounts of carbohydrates, 75 g/h, were supplied during exercise and the insulin requirements were registered. Glucose was measured before, during and after exercise aiming at euglycaemia, 4-8 mmol/L (72-144 mg/dL). During the race, continuous glucose monitoring (CGM) was used as an aspect of safety and to allow direct and individual adjustments.

Results: Compared to ordinary carbohydrate supply during exercise, the high carbohydrate supplementation resulted in significantly increased insulin doses to maintain euglycaemia. During the cross-country skiing race, the participants succeeded to reach mean target glucose levels; 6.5 ± 1.9 mmol/L (117 ± 34 mg/dL) and 5.7 ± 1.5 mmol/L (103 ± 27 mg/dL) at the start and finish of the race, respectively. Episodes of documented hypoglycemia (<4 mmol/L/72 mg/dL) were rare. CGM was used for adjustments.

Conclusion: In this study, large carbohydrate supplementation in T1D individuals during prolonged aerobic exercise is safe and allows the subjects to maintain glycaemic control and indicates the feasibility of CGM under these conditions.