Hypo-METRICS study in continuous glucose monitoring

The use of continuous glucose monitoring (CGM) by individuals with type 1 diabetes (T1D) has “revolutionised the management of hypoglycaemia”, Dr Patrick Divilly, Consultant of Endocrinology and Diabetes Mellitus, St Vincent’s University Hospital, Dublin, told the inaugural Joint Irish-UK Endocrine Meeting 2024. He also highlighted issues surrounding hypoglycaemia in the age of new technology.

Dr Divilly compared the original definition of hypoglycaemia to CGM-detected hypoglycaemia. The latter relates to glucose levels below the hypoglycaemic threshold for at least 15 minutes and he emphasised that over 60 per cent of these episodes are asymptomatic.

He detailed his work in the Hypo-METRICS study, a multinational, multicentre investigation conducted as part of the HypoRESOLVE consortium. “The primary aim was to provide an evidence-based definition of CGM-hypoglycaemia and to further our understanding of clinical and psychological health impacts of hypoglycaemia,” said Dr Divilly, who provided a detailed account of the study methodology and recruitment process. Participants wore a blinded CGM device for 10 weeks and recorded their hypoglycaemia experiences “in real-time using a smartphone app”. The study recruited 350 participants with insulin-treated T2D, 200 with T1D and awareness of hypoglycaemia, and 50 with T1D and impaired awareness of hypoglycaemia.

“We asked them to report all episodes of hypoglycaemia that were either symptomatic episodes which resolved after carbohydrate ingestion or self-measured glucose of less than 4mmol/L. They also filled in three short surveys per day with key domains of quality-of-life that allowed us to compare the impact of days with and without hypoglycaemia.”

Findings from Hypo-METRICS revealed that while asymptomatic, sensor-detected hypoglycaemia went “unnoticed” and had no impact on daily functioning; however, episodes that were identified by participants did correlate with a negative impact on daily functioning.

“The real driver of reduced quality-of-life is not what the CGM is saying, but what the person is reporting to you,” Dr Divilly said. “The current consensus definition of hypoglycaemia doesn’t correlate well with the lived experience of hypoglycaemia,” he added, describing the steps being taken towards optimising definitions.

“What this might mean in the future is the development of personalised hypoglycaemia alarms. This would hopefully reduce the number of false alarms that people are experiencing, and reduce the psychological impact of hypoglycaemia without significantly increasing the biological risk; obviously within certain parameters. This might reduce alarm fatigue and diabetes stress, especially important with alarm fatigue being a key reason people discontinue a lot of the technology that we use…. The really important message is that the impact of hypoglycaemia on the person with diabetes depends not just on the threshold, but on their lived experience.”