Diabetes and Exercise at High Altitude

by Claire Pesterfield
Paediatric Diabetes Specialist Nurse, Children’s Services, Cambridge University Hospitals NHS Foundation Trust
The management of type 1 diabetes mellitus has changed over the years, with the modification of lifestyle playing an important role in today’s treatment modalities. One such aspect is that of physical activity and exercise.

The American Diabetes Association (ADA 1997) stated that:

“all levels of exercise, including leisure activities, recreational sports and competitive professional performance, can be performed by people with type 1 diabetes who do not have complications and are in good blood glucose control”.

For some people, a weekly aerobics class will suffice, but for others a more extreme activity is required, hence the increase in the number of people with diabetes participating in sports such as climbing, diving and marathon running.

This article looks at the experience of one such person (me!), climbing Mount Kilimanjaro - the highest free-standing mountain in the world - and what lessons can be learned to help nurses empower their patients to undertake similar activities.
Background
Standing at 5895m (19340ft) high, Mount Kilimanjaro is described as the ‘Roof of Africa’. There is a misconception that it is ‘easy’ to climb because no technical climbing ability is needed, however, people die every year trying. The Kilimanjaro National Park Authority estimate that only 40-50% of climbers successfully reach the summit and return.
In September/October 2004, three groups of climbers, 25 with diabetes, took on the challenge of reaching the summit of Kilimanjaro in order to raise funds for Diabetes UK. By the time the last group had returned, everyone had succeeded in reaching the top and raised nearly £200,000 for diabetes research. Everyone will have their own story of how they got to the top, but we all learned that diabetes is no barrier to achieving a dream if you work and prepare hard enough to achieve it.
The story for me started 12 months before the climb when I decided to fill in the application form, talk about it with my Diabetes Specialist Nurse and started to train. The training would have a dual purpose – not only would it ensure that I was fit enough to undertake the challenge, but it would also show how my diabetes would be affected by exercise. By measuring blood glucose levels both before and after exercise at hourly intervals for 6 hours to 12 hours it was noted that hypoglycaemia happened at differing intervals depending upon the intensity and duration of the exercise undertaken. The intensity of exercise was determined by the Karvonen formula for heart rate calculation (Ackland 2003). Although this was useful in training, these lessons cannot be related exactly to other situations such as high altitude hiking, as environmental factors can interfere with the normal physiological responses to exercise.
Preparation
I initially thought that this would be all I have to do, but then I started reading to learn more about the environment I would be spending 10 days in and realised that things would not be that simple! The height of Kilimanjaro is defined as extreme altitude as it sits above 5000m. Above this point, permanent human habitation is impossible, oxygenation decreases and temperature levels plummet.
The effects on the human body depend upon a person’s ability to acclimatize and are listed in Table 1. All of these side effects can have a severe impact upon the management of diabetes and must be considered before undertaking a trip such as this. To add to these difficulties, the management of diabetes itself can be further compromised due to the extreme altitude and temperature ranges that are encountered. This is where the help of an experienced and supportive Diabetes Health Care Team cannot be underestimated.
Before the adventure began, our kit had to be checked and packed. This turned out to be a bit of a joke for all of us as we had to pack for a variety of weather conditions from 30 degrees on the African plain to -25 degrees on the summit – no mean feat when the weight limit is 15 kilos! Added to this was the diabetes supplies I needed to take as well as the snacks and hypo treatments. Excess packaging was reduced to a minimum, with supplies for my insulin pump opened and the packaging being thrown away. Insulin was drawn up into reservoirs and these pre-prepared sets then contained in a sealed bag alongside a handful of alcohol swabs. Although this increased the risk of infection, it was a risk I was prepared to take.
All foodstuffs were chosen based on their high carbohydrate content and their packaging again was kept to a minimum. It was important to choose a variety of foods that would not melt in the warm environments, but also would not freeze as the temperature dropped. Concentrated fruit bars seemed to be the best choice and at least would also offer a variety of flavours! Blood glucose testing strips were piled into as few containers as possible, and the luxury of using a new lancet for each blood test would just have to wait!
The Experience
Having managed to squeeze all my clothes, sleeping bag and diabetes kit into my rucksack, it was time to head off to the airport, meet the team and fly off to begin our adventure. The next 24 hours were spent sitting down in airports, planes and buses, consequently, blood glucose levels were a little higher than normal. This was easily counteracted by increasing the basal rate on my insulin pump. Lunch was held in the middle of the African savannah, with tables, chairs and even a portaloo! Our drive through to our first camp allowed us to see herds of giraffe and zebra as well as remote Maasai villages. The food was not as different as we all thought it might be – they obviously had done their homework about our nutritional needs and every meal was packed full of carbohydrates as well as fresh fruit and plenty of tea, coffee and Milo (a kind of hot chocolate which we all came to adore by the end of the trek).
The trek started the following day after a drive through more remote villages into the African lush rain forest. This was a relatively short day as we had spent a lot of time meeting our support crew and sorting out what gear to take up the mountain and what to leave behind at our base camp. If every day was like this then reaching the top shouldn’t be that hard! Day 2 would change any misconceptions we had about the trek! The day consisted of walking through more dense forest, which at times resembled a mud path due to the high rainfall. This made walking hard work and although I had reduced my insulin, it obviously was not enough. This is where the convenience and flexibility of an insulin pump shines through as I reduced my basal rate further which would take immediate effect (see Table 2 for diabetes management during the trek). It was fortunate, as the afternoon saw us gain 600m in height, the temperature drop significantly and more hypoglycaemic attacks.
Prolonged exercise such as hiking, marathon running and cycling relies on the aerobic system to provide the energy required. The fuels used are a mixture of carbohydrates and fat. Protein also has a role but usually during very prolonged activities and then only to a minor extent (ADA 1997). The extent of carbohydrate utilization depends upon the intensity of the exercise undertaken. High intensity exercise will use 100% carbohydrates, with muscle glycogen and blood glucose being used most. At lower intensities such as hiking and backpacking, circulating hormones such as epinephrine mobilize fats from adipose stores to be used as energy. However, these rules need to be adapted for working at altitude as this creates an additional strain on the body. McKean (2005) claims that initial exposure to altitude causes an increase in the use of blood glucose as an energy source and a decreased reliance on the use of fat stores. As a result, fatigue and hypoglycaemia are more likely to occur at the same intensity of activity at altitude compared to that of sea level, and therefore insulin requirements need to be reduced.
Day 3 was a short day for walking but would include an acclimatisation trek up to 4,100m on the Shira Needle. The landscape had changed from warm, lush rainforest to heath land and alpine desert which meant we were now exposed to chilling winds and freezing mist. Our energy requirements increased in line with the increase in altitude and we tried to stay warm. Frequent snacks were needed to prevent glycogen stores from becoming depleted but the altitude was now beginning to affect my appetite.
To reduce the risks of dehydration and altitude sickness it was necessary to drink at least 3 – 5 litres of fluid a day. Drinking so much fluid reduced the appetite, so compromise was reached by adding powdered sports drinks to add flavour as well as carbohydrates. Hot drinks were very welcome but caffeine intake should be reduced to minimise the effects of Acute Mountain Sickness (AMS), so hot Milo was very popular. However, the lack of caffeine can make hypoglycaemic warning signs more subtle in some patients with Type 1 diabetes (Debrah et al 1996, Watson and Kerr 1999), so it is necessary to weigh up the potential risks individually.
After each day of hiking it was important to replenish glycogen stores in order to prevent blood glucose levels dropping during the night and to ensure that there would be enough energy stores to continue the next day. The risk of hypoglycaemia after exercise can be present for up to 48 hours after the activity due to the heightened insulin sensitivity during muscle glycogen replenishment (ADA 1997) and therefore good nutritional intake throughout the trek was vital.
There are a number of studies that show that glycogen replenishment is best achieved within the first six hours (and in particular the first two) with high glycaemic foods that are rapidly absorbed into the blood stream. On arriving in camp each evening, hot popcorn and more hot Milo was available in the mess tent and everyone was encouraged to tuck in as much as they could until the evening meal arrived.
At this altitude, temperature levels were beginning to drop. During the day, they can reach up to 30ْC, but at night they can plummet to well below zero. On average, the temperature will drop 1ْC for every 200m gained in height. During the day it was important to stop the insulin from getting too warm, but at night it was vital to prevent it from freezing. This was achieved by having the insulin, blood glucose meter, testing strips, and hypo treatment in the sleeping bag with you overnight and wrapping it in a spare fleece (if there was one!).
As the altitude increases it affects the body in peculiar ways. Add to that the increased fluid intake necessary to reduce altitude sickness means that it is nearly impossible to sleep through the night without wanting to go to the loo! But it could also mean that the blood glucose levels have risen to a higher level. Here lies a difficult but important question. Do you fumble in the bottom of your sleeping bag to find your meter and hope that it is warm enough to give you an accurate reading before you step outside, or do you quickly get dressed, go about your business and try to forget about the possible causes? To be honest, most of the time, it was so cold and the level of exhaustion so great, testing was not really an option in the middle of the night. However, to make up for it, the view from the toilet (usually a handy large rock nearby) a spectacular clear sky with gleaming bright stars was compensation enough!
As the next three days went by, the walking became more arduous, the temperature dropped, the strain on the body increased and energy levels waned. My blood glucose levels were reading higher than I expected for the effort I was putting in and I began to wonder if my meter was accurate. The normal symptoms of hyperglycaemia were easily masked by my aching limbs, frequent loo stops but I remembered reading an article about a group from Ireland who climbed Kilimanjaro a few years before where they noticed that as they climbed higher, insulin requirements actually increased (Moore et al 2001).
Reaching the Summit
As the summit attempt approached, I was confident that my diabetes would not hold me back, but it would be down to the weather conditions, a bit of luck and a lot of determination. My rucksack was packed full of food and water and I decided to wear all the clothes I had, as the wind was howling and the temperature had dropped to around -15ْC. I had packed all the important equipment close to me as I did not want it to freeze, or to stop to find it in my pack. I had also taped my infusion set from my insulin pump to my body to prevent any chance of it being exposed to cold air and freezing. We all left camp at 10pm and aimed to climb through the night in order to reach the summit at day break where we could all sit as a group on top of Africa and watch the sun rise.
Conditions worsened, with the temperature dropping. My water froze and every time I stopped to catch my breath or eat a snack, I began to shiver with cold. There was no point in testing as I could not be bothered to take my four pairs of gloves off to find a finger to prick, let alone unzip my jackets to find my meter! This was the hardest thing I have ever done (or likely to do), but the images of my friends and family back home who have supported me from the start kept me going, as well as the chance to sit on top of Kilimanjaro and be warmed by the sun.
Well, I made it to the top, but it was not the picture postcard that any of the group had imagined. The weather had deteriorated into the worst conditions for years with the temperature dropping to below -25ْC and blizzard conditions. There would be no basking as the sun rose – it was a quick cup of celebratory Milo, the obligatory summit photograph, and a three hour trek back down to camp for a few hours sleep before we were due to descend further to a lower camp.
Conclusion and Reflection
The experience of ‘summiting Kilimanjaro’ has answered a lot of questions and been an invaluable experience. Not only have I made a number of great friends but I have also learnt that with the right research, support and preparation, people with diabetes can and do achieve things that were once thought inconceivable and unattainable. It should not be used as a barrier to achieving goals, but as a motivating factor to encourage and develop self-care skills and empowerment.
As nurses, we have a role in supporting our patients in the achievement of their goals, no matter what field we work in and by working together as an equal partnership we can learn from each other.
Acknowledgements
There are a number of people whose help and support were instrumental in the success of this trip, some of which are listed below. Without them, achieving my dream would not have been possible.
Helen Reid
Colin Moon
Pauline Weir

Candice Philipps
Medtronic MiniMed
… and all the guys involved in Trek No 3, both climbers, guides and support crew.
References
Ackland J (2003) The Complete Guide to Endurance Training. London: A&C Black
ADA (American Diabetes Association) (1997) The Diabetic Athlete – Prescriptions for Exercise and Sports. USA sorry – cannot find one!: Human Kinetics
Debrah K, Sherwin R, Murphy J, Kerr D (1996) Effect of caffeine on recognition of and physiological responses to hypoglycaemia in insulin dependent diabetes. Lancet 347:8993;19-24
McArdle W, Katch F, Katch V (2001) Exercise Physiology – Energy, Nutrition and Human Performance 5th edition. USA Baltimore: Lippincott Williams & Wilkins
McKean R (2004) Optimal Fuel – fat, carbohydrates or protein? Nutritional information for high altitude sports. Available: http://www.scottishsport.co.uk/running/altitude3.htm Last accessed 09.01.2005
Moore K, Vizzard N, Coleman C et al (2001) Extreme altitude mountaineering and Type 1 diabetes; the Diabetes Federation of Ireland Kilimanjaro Expedition. Diabetic Medicine 18:9;749-755
Watson J, Kerr D (1999) The best defense against hypoglycaemia is to recognise it: is caffeine useful? Diabetes Technol Ther. 1:2;193-200 Review

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