Delayed hypoglycaemia in people with type 1 diabetes after performing moderate intensity exercise before the evening meal

For a person with type 1 diabetes, participation in exercise may increase the risk of hypoglycaemia. Research has been performed during or immediately after exercise in a laboratory environment, with limited evidence regarding strategies for post-exercise hypoglycaemia prevention. The aim of this study was to investigate the occurrence of delayed hypoglycaemia after 40 minutes of moderate intensity exercise at 70% VO2 max before the evening meal, in both the real-life and laboratory exercise environments. Nine individuals (five males, four females) with type 1 diabetes using basal bolus analogue insulin regimens participated. All performed two sessions of 40 minutes of moderate intensity exercise in two environments (laboratory and real-life), while following a self-management algorithm that included a 30% reduction of post-exercise evening meal insulin. Data were collected by continuous glucose monitoring for episodes of interstitial glucose <4.0 mmol/L at two-hourly time-points for 12 hours post-exercise. Before the evening meal, the mean blood glucose concentrations were: laboratory 8.0 ± 1.9 mmol/L and real-life 9.9 ± 4.1 mmol/L. During 2–6 hours after exercise, episodes of glucose concentrations <4.0 mmol/L were: laboratory n = 5, and real-life n = 2. This compared to 8–12 hours after: laboratory n = 3, and real-life n = 8. Hypoglycaemia unawareness was noted in eight of all 18 post-evening meal episodes of <4.0 mmol/L (laboratory n = 5, real-life n = 3). Despite post-exercise fast-acting insulin dose reduction of 30%, delayed hypoglycaemia occurred in both environments with an increase during 8–12 hours in the real-life environment. Recommendations from data suggest carbohydrate consumption at bedtime, and evening exercisers to perform blood glucose monitoring 8–12 hours post-exercise. Copyright © 2015 John Wiley & Sons.