In this brief report, we describe the feat of four men with type 1 diabetes mellitus (T1DM) who decided to take part in a mountain ultramarathon in Bieszczady, Poland on May 27, 2016. Before participating in the competition, they asked two diabetologists for a consultation and to assist in diabetic control during the marathon. The aim of the study was to assess the metabolic safety in people with T1DM during extreme physical exertion in a mountain ultramarathon. All subjects were treated with continuous subcutaneous insulin infusion. The marathon route was 82 km, and the sum of the climbs and descents was 3235 and 3055 m, respectively. Diabetologists controlled glucose levels using a glucometer, plasma lactate levels, and ketones in the capillary blood. In addition, they monitored the intake of carbohydrates and fluids. Clinical tests were performed at the three checkpoints (at 32, 49, and 66 km) during the race and after completing the race (at 82 km). This study shows that extreme physical exertion by a person with type 1 diabetes is possible. All subjects avoided severe hypoglycemia by significantly reducing their insulin dose and consuming additional carbohydrates. Such actions, despite the occurrence of hyperglycemia >250 mg/dL did not result in ketoacidosis. Safe participation in mountain ultramarathons by people with type 1 diabetes can be achieved if they undertake appropriate physical and diabetologic preparation.
Keywords: Continuous glucose monitoring; Extreme sports; Hypoglycemia; Insulin pump; Type 1 diabetes; Ultramarathon.