Glucose Management During a Competitive Game or Event

During competition, aiming for a glucose level of 7-8 mmol/L (126-145 mg/dL) is a good starting point to help achieve peak performance. Having fast-acting carbohydrates and insulin readily available (depending on the constraints of the event) is crucial for immediate adjustments as needed. Environmental factors, such as weather conditions, can also impact glucose levels, with both heat and cold affecting the body’s response (see below for more details). For example, ice hockey players may experience different glucose responses than field hockey players due to the cold environment.

Proper hydration is essential, as dehydration can cause glucose levels to drop rapidly. This is particularly important in high-intensity sports like basketball and hockey, where fluid loss can be significant. Stress levels may rise at key moments of a game, which can also impact glucose levels. Higher-stakes games may cause a more significant adrenaline-induced spike in glucose levels. Being mindful of stress levels and accounting for them can aid in effective glucose management. Minor adjustments of insulin and carbohydrates can be made to find the right glucose level for optimal performance.

 

Some Sport-Specific Considerations

Each contact team sport has unique demands that can influence blood glucose levels, so it’s essential to develop an individualised approach based on trial and error. By being strategic and adaptable, you can optimise your performance and manage your glucose levels effectively, no matter the sport:

●     Football (Soccer): The combination of aerobic and anaerobic activities requires careful management of insulin and carbohydrate intake. Monitor glucose levels frequently, as the intensity and duration of matches can vary.

●     Rugby: The high-impact nature of rugby can increase adrenaline levels dramatically, which may raise glucose levels. Adequate hydration and frequent glucose testing are crucial.

●     Field Hockey: The continuous running and skill-based movements in field hockey require sustained energy levels. Ensuring adequate carbohydrate intake before and during the game is essential.

●     Ice Hockey: The cold environment and intense, intermittent activity can affect glucose levels differently than other sports (as discussed later in this Chapter). Warming up properly and monitoring glucose levels closely are important.

●     Basketball: The fast-paced nature and frequent sprints can lead to rapid changes in glucose levels. Stay hydrated and monitor glucose levels regularly.

 

Post-Competition Glucose Management

Effective post-game management is also important for optimising recovery and maintaining safe glucose levels. After the game, adequate caloric and carbohydrate intake is crucial for replenishing energy stores (see Chapter 5 for more information). Considering the impact of the exercise on insulin sensitivity is important, which is especially relevant if the game was played in the late afternoon or evening (as there is an increased risk for nighttime hypoglycaemia). Refuelling properly, considering changes in insulin sensitivity, and staying hydrated are all essential elements of post-competition management and recovery. Continued monitoring of glucose levels post-game can help prevent delayed hypoglycaemia. It’s all about being proactive and strategic, ensuring your body has everything it needs to recover effectively.

 

Final Word on Contact Team Sports

Managing blood glucose levels before, during, and after contact team sports requires a holistic approach that includes the following:

• Pre-Game: Thorough planning, consistent routines, and adequate sleep.

• During the Game: Maintaining target glucose levels if possible, staying hydrated, managing stress, and having support nearby to check glucose levels and provide fast-acting carbohydrates when required.

• Post-game: Proper refuelling, consideration of changes in insulin sensitivity, and continued monitoring of glucose levels are essential for optimal recovery and glucose management.

Regular consultation with healthcare providers can also provide personalised advice and support for managing blood glucose levels during physical activity.

 

Navigating Water-Based Sports: Swimming and Diving with T1D

In addition to the above general considerations about frequent glucose monitoring and planning, there are some particular considerations for water activities. Prolonged water exposure can compromise the adhesion of CGMs and insulin pumps, potentially leading to device failure or inaccurate readings. Moreover, the intense physical exertion associated with water-based activities can significantly lower blood glucose levels, increasing the risk of hypoglycaemia. To overcome these challenges, consider the following:

1.       Waterproofing Devices: Secure CGMs and insulin pumps using waterproof adhesives or patches to minimise the risk of dislodgement or malfunction. Always test the waterproofing method before engaging in water-based activities to ensure effectiveness.

2.       Hydration and Quick-Acting Carbohydrates: Stay hydrated and have quick-acting carbohydrates readily available. Prolonged physical exertion and the body's response to water immersion can affect hydration status and increase the risk of hypoglycaemia. It is crucial to replenish fluids and consume snacks as needed.

3.       Lack of Device Communication between CGM and Automated Insulin Delivery (AID) Controller: Be aware that communication between the CGM and the AID controller may be disrupted during water-based activities.

4.       Avoid High Insulin on Board at the Start of Water-Based Activities: If you suspend a pump or AID system, avoid disconnecting it where possible. However, consider reconnecting it regularly for a small amount of insulin delivery [7].

5.       Insulin Pump Disconnection: If insulin pumps are disconnected for more than 2-3 hours, consider using additional basal insulin to avoid the development of DKA.

Additionally, be mindful of the potential risks associated with water-based sports, such as the increased energy demands and the impact of water temperature on the body's physiological responses. Cold water, for instance, can accelerate glucose utilisation and increase the risk of hypoglycaemia. Consulting with healthcare providers can offer personalised advice on managing blood glucose levels during water-based activities, tailored to everyone’s unique needs and diabetes management plan.

By implementing these strategies and considering the specific challenges of water-based sports, individuals with T1D can safely engage in swimming, diving, and other aquatic activities while effectively managing their blood glucose levels.

 

Open Water Swimming

Swimming in open water presents additional challenges, such as changes in humidity and water temperature, and it may be less predictable than swimming in a pool. Therefore, careful planning and strategic management are essential for safe and enjoyable open-water swimming. Published data on T1D and endurance swimming are extremely limited, with some individual and small-group case reports from triathlon competitions [8].

 

Scuba Diving

Until quite recently, recreational scuba diving was prohibited for people with T1D in some countries [9] due to the perceived high risk of hypoglycaemia during dives and the subsequent risk of drowning. However, this risk had not been substantiated or assessed. Towards the end of the 1990s and early 2000s, several studies demonstrated that divers with T1D did not experience more diving accidents than others [10, 11]. Based on the results of these studies, many countries have lifted the ban and progressively loosened associated restrictions [9]. Nevertheless, until relatively recently, the ban still applied to individuals with T1D under 18 years old.

Lormeau et al. [9] evaluated the conditions under which diving could be authorised for adolescents aged 14 to 18 with T1D and assessed the value of CGM while diving. Based on this study, the French Underwater Federation has now authorised diving for adolescent T1D following a specific diving protocol:

• Dive Frequency: Only one dive per day is currently authorised.

• Parental Consent and Supervision: Parental authorisation for diving is required, with a parent or legal representative present on the dive boat.

• Medical Clearance: A medical certificate signed by a diabetologist or a paediatrician stating that the individual has an HbA1c level <8.5%, no ketosis or severe hypoglycaemia in the three months before the issuance of the certificate, and the ability to self-manage diabetes.

• Diving Protocol:

o   Reduction of insulin doses (basal −20% and bolus −50% before the dive).

o   Target pre-dive blood glucose level > 250 mg/dL, with the dive being cancelled if <200 mg/dL.

o   No correction of hyperglycaemia up to 300 mg/dL and a correction bolus reduced by 50% if >300 mg/dL.

o   Glucose monitoring can be done either by capillary glucose testing or using CGM.

• CGM Users: It is strongly recommended that patients using CGM have a capillary glucose monitoring system available for redundancy because CGM sensors can be dislodged or malfunction.

 

Environmental Challenges and Considerations

Exercising in Cold Temperatures

Cold temperatures can slow down insulin absorption from the injection site. This happens because vasoconstriction reduces blood flow to the skin and subcutaneous tissue, leading to a delayed onset of insulin action and increasing the risk of hyperglycaemia during exercise. Cold temperatures can also affect the functionality of insulin pumps and CGMs (it is advisable to check the information about ‘temperature range with guaranteed function’ according to the manufacturer), potentially leading to device malfunctions or inaccurate readings.

Impact of Cold on Diabetes Technology

Insulin pumps and CGMs are designed to operate within specific temperature ranges. Exposure to cold temperatures can impair their performance. In freezing temperatures, insulin becomes more viscous, which can affect its delivery through insulin pumps. Similarly, the sensitivity and accuracy of CGMs may be compromised, leading to unreliable glucose readings. To avoid these issues, providing additional insulation and protection for these devices when exercising in cold environments is crucial.

 

Management Strategies and Considerations During Low Temperatures

To effectively manage blood glucose levels and maintain the functionality of diabetes technology in cold temperatures, individuals with T1D should consider the following:

• Keep Devices Warm: Position insulin pumps and CGMs close to the body and use insulated pouches to help maintain their warmth. This will ensure that they remain within their optimal operating temperature range.

• Frequent Blood Glucose Monitoring: Check glucose levels more often to adjust insulin doses in a timely manner. This helps account for delayed insulin absorption and the body's increased glucose demands during exercise in cold conditions. Consider setting a higher alert threshold on a CGM when possible.

• Stay Hydrated and Consume Carbohydrates When Needed: Cold temperatures can blunt the sensation of thirst, increasing the risk of dehydration, which can, in turn, affect blood glucose levels. Consume adequate fluids and carbohydrates to ensure the body has the necessary fuel to maintain blood glucose levels and support physical exertion. Avoid taking carbohydrates that may freeze.

Additionally, individuals with T1D should be aware of the signs of hypothermia, as prolonged exposure to cold temperatures can lead to a dangerous drop in body temperature. Symptoms such as shivering, confusion, and slurred speech should not be ignored, and appropriate measures, including seeking warmth and medical attention, should be taken promptly.

 

Exercising in High Temperatures

The combination of high temperatures and the body’s physiological response to exercise requires close monitoring and strategic adjustments to insulin dosage, hydration, and nutrition. Understanding how heat affects the body and, consequently, blood glucose management is essential for safe and effective exercise in warmer weather conditions.

In high temperatures, insulin absorption from the injection site may speed up due to the dilation of blood vessels. This physiological response enhances blood flow to the skin and extremities for heat dissipation. The increased absorption rate can lead to a more rapid onset of insulin action, thereby elevating the risk of hypoglycaemia. At the same time, the body's demand for glucose may increase due to the increased energy requirements for thermoregulation and the intensified metabolic rate during exercise. These factors make it challenging for individuals with T1D to predict their blood glucose response to exercise in hot environments, underscoring the need for vigilant glucose monitoring and proactive management strategies.

 

Considerations and Management Strategies in Hot Climates

To reduce the risks associated with exercising in high temperatures, individuals with T1D should prioritise several essential strategies:

• Stay Hydrated: Preventing dehydration is crucial, as it can exacerbate the risk of hyperglycaemia by reducing blood volume and impairing glucose regulation.

• Proper Insulin Storage: Keeping insulin cool using insulated pouches or cooling packs can help maintain its efficacy and prevent degradation due to heat exposure.

• Frequent Blood Glucose Monitoring: Checking glucose levels more often allows for timely adjustments to insulin doses, ensuring that blood glucose remains within a safe range despite the added variability imposed by high temperatures. Consider fingerstick blood glucose monitoring in cases where CGM accuracy may be impacted [12].

• Secure Devices: Use an overlay patch and/or tape to keep your CGM and insulin delivery device in place during hot weather, especially with increased perspiration.

Furthermore, individuals with T1D must recognise the signs of heat exhaustion and heatstroke, as these conditions can significantly impact blood glucose levels and overall health. Symptoms such as dizziness, fatigue, headache, and excessive sweating should not be ignored. Take appropriate measures promptly, including rest, hydration, and cooling. Consultation with healthcare providers can offer personalised advice on managing blood glucose levels during exercise in high temperatures, tailored to everyone’s unique physiology and diabetes management plan (see Chapter 5 for more information on fluid intake and hydration during exercise).

 

Exercising at Altitude

The reduced oxygen levels at altitude can impair physical performance and alter the body's response to insulin, making blood glucose management more complex. Often, the initial stress of high altitude can activate the sympathetic system and trigger the release of counterregulatory hormones, leading to hyperglycaemia. Conversely, after some time at a high altitude, hypoglycaemia risk increases due to hypoxia-induced enhanced insulin sensitivity with potentially increased glucose uptake by muscles. Hence, in general, short-term exposure is followed by hyperglycaemia whilst long-term exposure is associated with lower plasma glucose levels [13]. Additionally, the symptoms of altitude sickness, such as fatigue, dizziness, and nausea, can mimic or mask those of hypoglycaemia, making it difficult to distinguish between the two. Therefore, people with T1D must be vigilant in monitoring their blood glucose levels, adjusting insulin doses accordingly, and staying hydrated while exercising at high altitudes. Consulting with a healthcare provider before engaging in such activities is crucial for developing a safe and effective management plan.

Key Considerations During Winter Sports:

●     Altitude and the Initial Stress Response: Exposure to altitude can first lead to increased blood glucose levels. The lack of oxygen leads to a stress response and the release of hormones (adrenaline, noradrenaline and cortisol). In the presence of these hormones, the liver releases more glucose, and the effectiveness of insulin might thereby be diminished in the beginning [14].

●     Physical Activity, Altitude, and Insulin Sensitivity: Combining physical activity with exposure to higher altitudes increases insulin sensitivity, increasing the risk of hypoglycaemia [15-17].

●     Cold Temperatures: Cold can slow insulin absorption and affect the performance of diabetes technology. Avoid freezing of insulin [17].

●     Impaired Decision-Making: Hypoxia may negatively impact your decision-making process.

 

Management Strategies

●     Altitude Adjustments: Monitor blood glucose more frequently and adjust insulin doses as needed. Altitude can increase insulin sensitivity.

●     Keep Devices Warm: To maintain warmth, keep insulin pens, pumps, and CGMs close to the body. Consider using insulated pouches.

●     Hydration and Nutrition: Stay hydrated and carry quick-acting carbohydrates. High-altitude activities can increase calorie burn.

Blood glucose meters [18] and continuous and flash glucose monitoring systems have been reported to measure glucose reliably at high altitudes [19]. However, the available data on this is quite limited, and it is often experienced that CGMs might be inaccurate at high altitudes.

At elevations ≥3600 m, interstitial glucose levels might be elevated [19]. In people with T1D, it is difficult to provide general recommendations regarding insulin administration strategies since variable glucose responses have been observed, depending on the rate of ascent and altitude attained [15, 20]. Due to this, alternating glucose and insulin requirement strategies to overcome glycaemic disturbances should be tested in advance to be individually tailored. For safety reasons and to incorporate potential sensor inaccuracy, we advise that a higher glucose level of ~160-180 mg/dL (9.0-10.0 mmol/L) should be targeted. Glucose should be measured as often as possible, and if needed, only micro doses of bolus insulin should be given. Since high altitude is associated with cold temperature, the sensor should be worn at a site that will help keep it warmer (e.g. on the stomach). The scanner/reader should also be worn close to the body, so the temperature does not fall below ~4 degrees Celsius (~39 degrees Fahrenheit).

Why Universal Exercise Protocols That Account for Every Scenario Aren’t Possible (at least not yet)

Given the highly individualised nature of glycaemic responses to exercise and the numerous influencing factors, it is currently not practical or feasible to provide exercise plans that work for everyone with T1D. Healthcare providers and individuals living with T1D must work collaboratively to tailor exercise routines based on individual needs, preferences, and physiological responses. Regular monitoring, adjustments, and at least a basic understanding of how exercise, insulin, and blood glucose levels interact are essential for safe and effective exercise management in T1D.

Why is it so Difficult to Develop Protocols to Suit Every Environment and Individual? – Challenges in Exercise and T1D Research

Perhaps you’ve wondered how exercise guidelines are developed. The primary method used to generate the exercise guidelines for people living with T1D is the randomised controlled trial or RCT. This is a form of scientific experiment used to control factors that are not under direct experimental control. RCTs in clinical research typically compare a proposed intervention, in this case, the effects of an exercise modality on a particular outcome, e.g., glucose levels. This approach offers a high degree of control over external variables and helps determine the effects on the independent variable, providing a high degree of reliability. The RCT is designed to reduce bias and rigorously examine cause-effect relationships between an intervention and its outcome.

However, while the benefits of exercise for individuals with T1D are indisputable, several limitations in the existing research make it challenging to provide universally applicable protocols around how to manage glucose during exercise. These limitations include:

• Heterogeneity of Responses: People with T1D show considerable variability in their blood glucose responses to exercise. This heterogeneity is influenced by factors such as insulin sensitivity, duration of diabetes, and individual physiology, making it challenging to develop one-size-fits-all recommendations.

• Small Sample Sizes: Many studies on exercise and T1D have small sample sizes, which can limit the statistical power and generalizability of the findings. It’s quite common to find studies in this area with no more than 12 participants, with some having as few as seven. Larger, more robust studies are needed to draw definitive conclusions.

• Varied Exercise Protocols: Research studies have employed a wide range of exercise protocols, differing in intensity, duration, and type of exercise. This variability makes comparing results across studies and developing standardised guidelines challenging.

• Lack of Long-Term Studies: Most research focuses on the acute effects of exercise on glucose levels. There is a lack of long-term studies investigating the sustained effects of regular exercise on glycaemic management and overall health in individuals with T1D.

• Technological Limitations: While closed-loop systems and CGM hold promise for improving exercise management, these technologies are still evolving. Current systems may not be sufficiently responsive to the rapid changes in glucose levels that occur during and after exercise [21, 22]. A challenge for the engineers developing algorithms for closed-loop systems has been a lack of sufficient data in the context of exercise.

• Artificial Conditions: Laboratory-based studies are conducted under conditions that may not accurately reflect real-world exercise scenarios (such as stressful competitive situations, temperature changes, variable exercise intensities, etc.), potentially limiting the applicability of the findings.

• Unrepresentative Samples: Most studies conducted in T1D and exercise research have included predominantly white male participants, often comprising university students. This limits the generalisability of the findings.

These challenges highlight the need for more comprehensive and diverse research to develop practical and personalised exercise guidelines for individuals with T1D. These limitations are partly due to the complexity and costs of conducting these types of studies. To be clear, we do not wish to discredit any researchers who have conducted these studies or developed the existing guidelines. We know from personal experience of conducting many RCTs ourselves that they are complex and time-consuming.

Looking ahead, particularly with the rise in remote monitoring technology such as CGM and wearables, lab-based RCT may be supplemented with remotely conducted home-based interventions [23-27]. This will allow for more extensive and varied participant samples to be included.

 

The Final Word

For individuals living with T1D, exercise presents numerous challenges. Nevertheless, reaching an elite or professional level in sports is possible. While these goals are achievable, it is essential to acknowledge the additional obstacles and identify areas for improvement and support to enhance the likelihood of success. Understanding how changes in the environment or sporting situations can influence blood glucose management is crucial for enjoying and participating in sports, regardless of the conditions.