Metabolic regulation during constant moderate physical exertion in extreme conditions in Type 1 diabetes

Constant moderate intensity physical exertion in humid environments at altitude poses a considerable challenge to maintaining euglycaemia with Type 1 diabetes. Blood glucose concentrations and energy expenditure were continuously recorded in a person trekking at altitude in a tropical climate to quantify changes in glucose concentrations in relation to energy expenditure.

Blood glucose concentrations and energy expenditure were continuously monitored with a Guardian® real-time continuous glucose monitoring system (CGMS) and a SenseWear® Pro3 armband (BodyMedia Inc., USA), in a 27-year-old woman with Type 1 diabetes, during her climb up Mount Kinabalu in Borneo (c. 4095 m). Comparative control data from the same person was collected in the UK (temperate climate at sea level) and Singapore (tropical climate at sea level). Maximum physical effort during the climb was < 60% VO(2MAX) (maximal oxygen consumption). Mean daily calorific intakes were 2300 kcal (UK), 2370 kcal (Singapore) and 2274 kcal (Mount Kinabalu), and mean daily insulin doses were 54 U (UK), 40 U (Singapore) and 47 U (Mount Kinabalu). Despite markedly increased energy expenditure during the climb [4202 kcal (Mount Kinabalu) vs. 2948 kcal (UK) and 2662 kcal (Singapore)], mean blood glucose was considerably higher during the trek up Mount Kinabalu [13.2 ± 5.9 mmol/l, vs. 7.9 ± 3.8 mmol/l (UK) and 8.6 ± 4.0 mmol/l (Singapore)].

Marked unexpected hyperglycaemia occurred while trekking on Mount Kinabalu, despite similar calorie consumption and insulin doses to control conditions. Because of the risk of unexpected hyperglycaemia in these conditions, we recommend that patients embarking on similar activity holidays undertake frequent blood glucose monitoring.