Expedition & Wilderness Medicine
As the medical management of diabetes improves, diabetics are increasingly becoming involved in adventurous persuits in the wilderness and on expeditions. The aim of this article is to attempt to demistify the subject of insulin dependent diabetes. Diabetics on expeditions may increase their risk of a number of medical problems: hypo and hyperglycaemia, dehydration, frostbite, infections, poor wound healing. There can also be diagnostic dilemmas of differentiating diabetes related disease with a number of tropical diseases and altitude related conditions. None of these are insurmountable but require more vigilance and proactive monitoring by the individual and the expedition medic.
A letter from the client’s own GP outlining the condition, including the need to carry syringes, is necessary for air-travel and useful for border crossings. Young active diabetics may be well in tune with their disease and used to altering doses, but do not assume this. Often they are managed with background 24 hour insulin e.g. glargine with easily alterable short-acting e.g. lispro. (basal-bolus regime). Of course an insulin pump would be even better. For some people it may be useful to convert to this regime before the trip; if so, allow plenty of time to get used to it. Typically a basal-bolus regime is the recommended for the potentially unstable and unpredictable environment on an expedition.
Diabetics need to be thorough in their preparation prior to an expedition. Testing their devices, trialing new regimes with increased levels of activity. Basically ensuring maximal stability of their disease before going on an expedition. Physicians should ensure the diabetic patient has pre-expedition HbA1c, tests to establish any end organ damage and a thorough understanding of how to manage their diabetes on expedition.
Careful planned adjustment of doses is needed over time zones for any flights. Most diabetics find it useful to change to the destination time zone on the flight. As a rule of thumb, if flying west, the day will lengthen and insulin doses may need to increase, whilst eastern journeys result in shorter days and hence less insulin may be required. Importantly the diabetic patient needs to monitor their blood glucose closely.
Once on expedition, diabetics ideally need regular meals, but this may not be possible. Regular monitoring is vital and they should always carry snacks. The medic should consider an antiemetic early if vomiting occurs. Be aware that there may be alterations in insulin requirements:
UP – illness / exertion
DOWN – after regular prolonged exercise
Some monitoring devices do not function well at altitude or in the cold. Those which use reagent strips with glucose dehydrogenase are more stable, but still do not read accurately above 2500m (though the error is probably not significant). The monitors and insulin must be kept at a relatively stable temperature and not agitated too much. Insulin is surprisingly resistant to denaturing but always check that it is clear and colourless before use. There are a number of storage devices, the easiest to use and most efficient is currently the Frio Bag.
Interestingly there have been several cases of ketoacidosis in IDDM patients at altitude using acetazolamide, and until a clear connection is established its use in diabetics is not recommended. The alternative treatment is dexamethasone, however this should not be used as a prophylactic treatment as it can induce hyperglycaemia.
Source: Dr Sean Hudson, Expedition Medicine, http://www.expeditionmedicine.co.uk/resource.php?id=105
Expedition & Wilderness Medicine
Relevant website; http://www.mountain-mad.org/
Expedition & Wilderness Medicine 