Hypoglycaemia in Clinical Diabetes

316 LIVING WITH HYPOGLYCAEMIAMost team sports, such as football and hockey, and competitive games such as squashor tennis usually have a predictable duration, but other activities such as swimming,cycling or running may be much more variable. Endurance sports and protracted anddemanding physical activities require more elaborate planning. Sustained exercise such ashill walking requires a premeditated reduction in total insulin dose of at least 20–30%.Teenagers with diabetes attending an outdoor activity holiday in Scotland reported that hillwalking, canoeing and mountain biking, all activities that involved intense exercise of longduration, were those most commonly associated with frequent and severe hypoglycaemia(Thompson et al., 1999). Long distance running requires a considerable reduction in insulindose. In 13 runners with insulin-treated diabetes who participated in the New York marathonthe total insulin dose was reduced by a mean of 38% (Grimm and Muchnick, 1993). Thefrequent ingestion of beverages and snacks that are rich in carbohydrate is also necessary. Apersonal account of a marathon run (Kjeldby, 1997) emphasised the difficulty in determininghow much intermediate-acting insulin to inject in the evening after the run, and the necessityto do frequent measurements of blood glucose over the next 24 to 48 hours to avoid delayedhypoglycaemia.Outward Bound mountain courses and holidays for young people with type 1 diabetes,which include rock climbing, canoeing, horse-riding, caving and mountain expeditions, havebeen described by Hillson (1984; 1987) who has detailed the sort of measures necessary forparticipants to avoid and to treat hypoglycaemia (Box 14.6). Anticipation of potential hazardsfor people with diabetes at risk of hypoglycaemia must be considered for all activities, withconsideration given to the timing of meals and administration of insulin, travelling timeBox 14.6 Measures to prevent hypoglycaemia in outdoor activities and holidays(derived from Hillson, 1984; 1987)• Reduce total insulin dose (by 10–15%).• Ensure a good intake of high-fibre carbohydrate with plentiful quick-actingcarbohydrate.• Increase carbohydrate at main meals and double the amount taken at snacks, or thenumber of snacks between main meals.• Consume glucose tablets or drinks immediately before climbing up or down anythinghigh, or during water activities.• Carry glucose at all times and keep by the bed at night.• Monitor blood glucose four times daily and respond appropriately to the results. Aimfor a blood glucose of ∼100 mmol/l. Blood glucose may be difficult to measure incold or wet weather.• Take an hourly snack during prolonged exercise such as cycling or mountainwalking.• Take a large pre-bedtime snack to avoid delayed hypoglycaemia.