Endocrine Abstracts

Introduction: Flash glucose monitoring is increasingly used in the management of T1DM. Although the FreeStyle Libre reduces the overall burden of conventional self-monitoring of blood glucose, capillary glucose should be checked at times of Libre-predicted extreme hypo/hyperglycaemia.

Methods: Consenting FreeStyle Libre users completed a structured questionnaire via phone interview. Users reported incidence of extreme hypo/hyperglycaemia (indicated by LO/HI outputs), subsequent actions taken, blood glucose levels correlating to LO/HI readings, use of Libre to guide insulin dosing, and any adverse outcomes directly linked to dosing insulin from Libre values.

Results: Seventeen Libre users participated (patient ages 7–17 years; MDI n = 6, CSII n = 11), length of Libre use ranged from 2 weeks to 3 years. 88% of participants report times the Libre indicated extreme hypo/hyperglycaemia by outputting ‘LO’ or ‘HI’. All (100%) of those users check their/their child’s capillary blood glucose when their Libre outputs LO/HI, in line with current recommended guidelines. 87% of users indicate their Libre readings are highly reliable in identifying extreme hypo/hyperglycaemia, as confirmed with blood glucose. Many users reported times their blood glucose levels were not as hypoglycaemic (53%) or hyperglycaemic (30%) as the Libre indicated. The majority of users (67% MDI, 100% CSII) use Libre readings to modify/guide insulin dosage; among users on CSII, 82% use Libre values always/almost always to determine insulin dosages. 93% of users report their/their child’s blood glucose consistently responds as expected to insulin they dose from Libre readings. Two users (both MDI) reported times their child became hypoglycaemic after they dosed insulin based on Libre readings.

Conclusion: Participants report the Libre accurately predicts extreme hypo/hyperglycaemia, and 100% of those users check capillary blood glucose at that time. Instances of adverse events highlight the need for increased Libre training for certain users. As the majority of users dose insulin based on Libre readings, frequently only checking blood glucose for readings significantly out of their target range, clinicians should be aware of a potential gap between medical advice and practical use of the Libre.