Effects of Prolonged Exertion on Glucose Management in Type 1 Diabetes: A 500 Mile Hiking Trek On the Camino de Santiago

For individuals with type 1 diabetes mellitus (T1DM) prolonged vigorous exercise requires careful planning to reduce risk of both hypoglycemia and hyperglycemia. In this case report we describe the experiences of a 59‐year old woman with T1DM who hiked the Camino de Santiago in Spain (805 km, 500 mile). Methods At the time of her trip she weighed 59 kg and height was 165 cm. She averaged 25.8 units/day total daily dose of insulin (56% basal), although this varied depending on her exercise level and less insulin was needed on days with physical activity. She used a continuous glucose monitor (CGM) [Dexcom G4® Platinum CGM (Dexcom Inc, San Diego, CA)] and an OmniPod® insulin pump system (Insulet Corporation, Billerica, MA). She wore a wGT3X‐BT triaxial accelerometry‐based activity monitor (ActiGraph Corporation, Pensacola, FL) on her left hip during the day and took it off at night. Results Thirty‐one of 33 trek days were included for analysis; 2 days excluded due to unreliable data. Her kilocalories of energy expenditure each day [Kcals (mean±SD) 1,481±523; range 248–2,332] and steps per day [33,340±9,828; range 5,239–50,454] mirrored the minutes spent in moderate to vigorous activity [MVPA minutes/day 316±108; range 54–484]. She hiked 21 – 40 km/day (13 – 25 miles) with 2 minimal activity “rest” days. There were 33 days of insulin pump and fingerstick blood glucose (BG) data; due to technical difficulties there were 14 days of CGM data. Her average total daily insulin dose during the trek gradually increased from 28 units/day to over 35 units/day, despite eating similar amounts of carbohydrates each day, reflecting an increased need for correction boluses (Figure). Her average morning fasting BG measurements stayed relatively stable (mid to low 100's mg/dL) until the last few days of the trip when her fasting BG rose to the 200 mg/dL range. Discussion In contrast to mild or moderate exercise, high intensity exercise may cause hyperglycemia that can last for several hours in individuals with T1DM. High intensity exercise may lead to increased insulin resistance and blood glucose levels may rise sharply and slowly decrease following exercise even with an increase in insulin doses. Studies have shown that continuous exercise mixed with intermittent high‐intensity exercise was associated with higher blood glucose concentrations compared to continuous moderate‐intensity exercise for 6 hours post‐exercise. Additionally, an increase in plasma lactic acid during prolonged exercise increases gluconeogenesis, and muscle damage that was not sufficiently repaired from day to day during 33 days of significant hiking likely contributed to our subject's increased insulin requirements. Conclusion Long‐distance hiking can be safely performed in persons with T1DM. However, individuals with T1DM must be aware that for prolonged exertion, insulin needs may increase despite increased exercise, and there is an increased risk of developing hyperglycemia. Planning for changes in insulin requirements on the days after prolonged exertion can help with diabetes self‐management. Support or Funding Information No funding was received. Product support came from Dexcom, Inc. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .