Post-exercise hypoglycaemia in adults with cystic fibrosis compared to healthy control adults

People with cystic fibrosis-related diabetes (CFRD) are at risk of hypoglycaemia related to insulin therapy; and hypoglycaemia is also prevalent in those without CFRD. Although people with other forms of diabetes mellitus are at risk of hypoglycaemia within 48 h after exercise, this has not been objectively measured in people with CF. This study investigated the prevalence of post-exercise hypoglycaemia in adults with CF (pre- and post-commencement of elexacaftor/tezacaftor/ivacaftor (ETI)), compared to healthy controls.

Participants completed a 20-min supervised, moderate-intensity cycling session and wore a continuous flash glucose sensor. The prevalence of hypoglycaemia was defined as the number of participants and percentage of time glucose levels were < 3.9 mmol/L and < 3.0 mmol/L within the 48 h after exercise.

15 adults with CF pre-ETI (abnormal glucose tolerance (impaired glucose tolerance, n = 2, or CFRD, n = 5)), 32 adults with CF post-ETI (21 abnormal glucose tolerance (impaired glucose tolerance, n = 10, or CFRD, n = 11)) and 15 healthy controls completed the study. There were no significant differences in the prevalence or duration of hypoglycaemia post-exercise between the CF and control groups; and no change after commencing ETI. There was also no significant increase in the prevalence or duration of hypoglycaemia for people with CF with abnormal glucose tolerance when comparing the 48 h post-exercise period to the 48 h period with the least exercise.

The absence of any increase in significant hypoglycaemia in the post-exercise period should be reassuring for people with CF who have abnormal glucose tolerance, whether prescribed ETI or not, and their clinicians.