Introduction

Sport can be unpredictable. Factors such as competition stress or changes in environmental conditions can significantly impact glucose management. Even if you are not a competitive athlete, numerous scenarios can dramatically affect your glucose levels or require additional considerations. These may include changes in altitude or a drop in temperature during winter sports, variables related to playing Sunday league football, or scuba-diving while on holiday.

When exercise conditions vary, it is essential to be strategic and consider specific factors to manage glucose levels effectively, whether training or competing. This chapter will delve into more advanced topics related to exercise and type 1 diabetes (T1D). This includes team sports (both contact and non-contact), pre-competition stress, swimming and diving, and how to handle environmental extremes such as variations in temperature and altitude. We’ll finish by offering some insights into how exercise guidelines are developed and why accounting for every environment or scenario remains such a huge challenge.

Contact Team Sports: Football, Rugby, Ice Hockey, Field Hockey, Basketball

Contact team sports like football, rugby, field hockey, ice hockey, and basketball present unique challenges for individuals living with T1D. These sports require dynamic, intense physical activity, necessitating a well-structured plan to maintain optimal glucose levels and performance.

Several factors need to be considered, including the timing of the game, the stress response and its impact on glucose levels, and aspects concerning diabetes technology, such as the positioning of glucose monitors or insulin delivery devices.

For those who regularly participate in competitive contact sports, choosing between an insulin pump and multiple daily injections (MDI) rests on various factors, including personal preference, ease of use, and safety considerations.  Insulin pumps offer several advantages over MDI, as they allow more precise and continuous insulin delivery, with increasing options for hybrid closed-loop systems. However, depending on the sport, there is the risk of the pump getting damaged or dislodged during the game, especially in high-contact sports. Using insulin pens eliminates the risk of dislodging the infusion set, and can be placed to one side during training or a game. Ultimately, the choice between an insulin pump and MDI therapy depends on individual needs, preferences, and advice from a healthcare provider.

Pre-Match Preparation

Effective blood glucose management before team sports requires thorough preparation.

1.       Develop a Plan:

• Consider the type, intensity, duration, and timing of the exercise, as well as meal timing in relation to the start of the exercise. Team sports typically combine aerobic and anaerobic activities [1-4], so anticipating the expected intensity and duration of the game and its potential impact on glucose levels can help adjust insulin and carbohydrate intake accordingly (see Chapter 3).

• Ensure sufficient time has passed since the last insulin bolus to reduce ‘insulin on board’ and lower in-match hypoglycaemia risk (as discussed in Chapter 4 – Timing of Exercise).

• Maintaining a consistent routine that has worked well in previous games can also be beneficial.

2.       Rest and Nutrition:

• A good night's sleep is crucial for optimising physical and mental performance.

• Consuming a balanced meal (in terms of carbohydrates and protein) at least 3 hours before the game allows for proper digestion and insulin action.

3.       Using Technology and Monitoring Glucose Levels:

• If you have access to a continuous glucose monitor (CGM), you and your coach can monitor glucose levels during the game and retrospectively analyse the data. This can help refine your routine for improved time in range during training and competition.

• Keeping track of glucose levels continuously during the game might be impractical, as most contact sports do not allow wearables or mobile phones. Therefore, a coach or other support person near the sidelines might be necessary to monitor glucose levels regularly—perhaps by holding onto your CGM transmitter or taking quick blood glucose samples whenever there’s a break in play.

• If you use a hybrid closed-loop system and you disconnect it during sporting activity, it is advisable to actively pause insulin delivery during non-use. This will inform the algorithm how long insulin delivery was suspended during the activity and therefore, accurately estimate insulin on board (IOB). If you disconnect the pump and let the insulin flow into the air without pausing, the AID system's algorithm would mistakenly assume the insulin has been delivered into the body, resulting in a falsely high IOB.

 

Pre-Competition Stress and Hyperglycaemia-Related Anxiety

It’s not uncommon for athletes to experience stress or anxiety before a competitive game or event, which can significantly impact blood glucose levels. Studies have shown elevated CGM traces before and during racing compared to training sessions [5].

Here’s what happens physiologically: Before an event starts, your body releases stress hormones such as adrenaline and noradrenaline. These hormones trigger a significant increase in glucose levels (Figure 1). In response to rising glucose levels, athletes might tweak their insulin management [5] or avoid carbohydrates in the lead-up to the event, fearing a further rise in glucose levels. This can backfire, resulting in insufficient fuel consumption during the event and potentially impairing performance [6].

Competition stress remains understudied and underreported, as reproducing its effects in the laboratory is challenging, and individual responses vary greatly. However, there is at least one case study that has documented the impact of hyperglycaemia-related anxiety during competition in an athlete with T1D [6].

So, what is the solution? We suggest that athletes employ a trial-and-error approach under the guidance of a medical professional. They should carefully monitor how glucose levels respond to specific stressful situations. This will help them develop a pre-competition strategy tailored to individual needs, including meal timing, insulin management, and starting blood glucose levels. Sports psychology support can also help reduce stress and prepare the athlete mentally for the event. This can positively influence glucose levels and lead to a positive feedback loop.