Till Örebro universitet

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.

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.

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.

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.