Do Insulin Users Know When Their Blood Sugar Is Low?

TOPLINE:
Among people with type 1 diabetes (T1D) and insulin-treated type 2 diabetes (T2D), at least half of hypoglycaemic episodes are asymptomatic, with nearly two-thirds of those < 70 mg/dL and over half of those < 54 mg/dL not identified by the person with diabetes.
At the same time, over 40% reported having hypoglycaemia when their glucose levels were > 70 mg/dL.
METHODOLOGY:
A total of 276 participants with T1D and 321 with insulin-treated T2D wore a blinded Libre 2 continuous glucose monitor (CGM).
They recorded patient-reported hypoglycaemia (PRH) — either symptomatic or a patient-measured glucose < 72 mg/dL — into the Hypo-METRICS app over 10 weeks.
Sensor-detected hypoglycaemia (SDH) was defined as a sensor glucose below the hypoglycaemia threshold for > 15 minutes.
Rates of SDH < 70 mg/dL, SDH < 54 mg/dL, and PRH were expressed as median episodes per week.
Episodes of SDH were matched to episodes of PRH that occurred within 1 hour.
A total of 37,386 days were recorded: 17,117 in T1D and 20,269 in T2D.
TAKEAWAY:
The median time < 70 mg/dL was 4.5% in T1D vs 1.4% in T2D, and time < 54 mg/dL was 0.6% vs 0.1%, respectively (P < .001 for T1D vs T2D).
All participants with T1D had ≥ 1 SDH episode during the study, and 96% had ≥ 1 SDH of < 54 mg/dL.
For SDH < 70 mg/dL episodes, 65% were not matched with PRH (ie, had no PRH within 1 hour of the SDH), with 61% of SDH < 70 mg/dL not matched in T1D and 76% of SDH < 70 mg/dL not matched in T2D.
After matching SDH to PRH, 6206 PRH (3794 in T1D and 2341 in T2D) were unmatched (not associated with SDH within 1 hour), equating to 43% of total PRH (37% in T1D and 58% in T2D).
IN PRACTICE:
“This study highlights the high proportion of hypoglycaemia on CGM that is not identified by people living with diabetes on insulin, and the high proportion of hypoglycaemia reported by people living with diabetes without corresponding SDH…These findings will have a significant clinical impact when interpreting CGM data and have implications on how we define impaired hypoglycaemic awareness and hypoglycaemic research outcomes in the future,” the authors wrote.
SOURCE:
Conducted by Patrick M. Divilly, MB, BAO, BCh, MRCPI, of Department of Diabetes, School of Cardiovascular and Metabolic Medicine and Sciences, Faculty of Life Sciences and Medicine, King’s College London, London, UK, and St Vincent’s University Hospital, University College Dublin, Dublin, Ireland, and colleagues. The study was published online August 29, 2024, in Diabetes Care.
LIMITATIONS:
Inclusion criteria of hypoglycaemia in the previous 3 months may have enriched the population for hypoglycaemia. Sensor accuracy might have accounted for some of the SDH-PRH mismatch. Although the study sensor was blinded, many participants had access to their own sensor during the study, which may have influenced their behaviours and/or treatment. The study was also conducted during the COVID-19 pandemic, which meant significant changes to daily life and changes in glycaemic outcomes. Predominantly White European population.
DISCLOSURES:
Supported by the Innovative Medicines Initiative 2 Joint Undertaking, which receives support from the European Union’s Horizon 2020 Research and Innovation Programme and European Federation of Pharmaceutical Industries and Associations and T1D Exchange, Juvenile Diabetes Research Foundation, International Diabetes Federation, and The Leona M. and Harry B. Helmsley Charitable Trust, as well as industry partners Abbott Diabetes Care, Eli Lilly, Medtronic, Novo Nordisk, and Sanofi-Aventis. 
Patrick M. Divilly has spoken at an educational symposium sponsored by Novo Nordisk. Other authors also have industry disclosures.
Abbott Diabetes Care provided the CGMs used in the study.
 
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