To the Editor: We read with great interest the recent article by Henriksen et al. [1], the aim of which was to ‘assess the effect of spontaneous nocturnal hypoglycaemia on quality of life and mood during subsequent days’ in adults with type 1 diabetes. The authors concluded that ‘individuals with type 1 diabetes and impaired hypoglycaemia awareness reported higher quality of life on days preceded by nights with asymptomatic (but not symptomatic) hypoglycaemia’ [1]. We think there may be other possible interpretations of the data, which indicate an urgent need for further research.
Henriksen et al. [1] used the EuroQol-5D visual analogue scale (EQ-5D VAS), which is a measure of perceived health status, not of quality of life. The VAS is a single item, usually presented in combination with the five-item EQ-5D, that asks participants to rate ‘how good or bad your health is today’ on a scale of 0 to 100. The single VAS item does not refer to quality of life in either the question wording or the anchors of the VAS. Many important studies, including the UK Prospective Diabetes Study (UKPDS) [2], have mistakenly assumed measures of health status to be synonymous with measures of quality of life. However, health is just one element of quality of life, and people with diabetes often consider other aspects, such as family, social life and work, to be more important to their quality of life than health status alone [3]. The limitations of misinterpreting the EQ-5D as a measure of quality of life have also been highlighted in the literature [3, 4].
Henriksen et al. [1] assert that the statistically significant difference in VAS scores observed the evening following an episode of nocturnal hypoglycaemia, as compared with nights without hypoglycaemia, is also a clinically important difference. However, the reference cited to support their approach [5] does not include data from people with diabetes. In addition, the previous publication [5] examined only the clinical significance of the EQ-5D descriptive system (i.e. the five items) without reporting a clinically important difference in VAS scores. The clinical importance of the difference in VAS scores is, therefore, uncertain.
Overall, we acknowledge Henriksen et al’s important contribution to understanding the impact of continuous glucose monitoring (CGM)-detected asymptomatic hypoglycaemia. Based on the above points, we believe the most accurate interpretation of the data is that CGM-detected asymptomatic nocturnal hypoglycaemia among people with impaired awareness of hypoglycaemia was associated with a statistically significant increase in self-rated ‘health status’ (as measured by the EQ-5D VAS), but that the clinical importance of this increase is uncertain. These findings make it clear that, as we focus on CGM-detected, asymptomatic hypoglycaemia in clinical care, we must understand its relevance and impact on self-management, health and quality of life. There are risks on either side if the impact is under- or over-estimated. The Hypoglycaemia – REdefining SOLutions for better liVEs (Hypo-RESOLVE) Consortium, funded by the EU IMI2, is already working on this important question [6]. As part of Hypo-RESOLVE, the Hypoglycaemia – MEasurement, ThResholds and ImpaCtS (Hypo-METRICS) study aims to use CGM in combination with a smartphone-based app that assesses daily functioning in the morning, afternoon and evening. This study will bring new insights into the temporal relationships between asymptomatic and symptomatic episodes of hypoglycaemia and daily functioning on a broad scale (e.g. sleep quality, mood, energy levels, cognitive functioning, social functioning and productivity) [6]. To fully understand how hypoglycaemia has an impact on quality of life, we need valid measurement, and this too is being investigated in the Hypo-RESOLVE project [7]. There is an urgent need for new instruments to capture the relevant impact of hypoglycaemia on quality of life.
We believe consideration of the above points and the research being conducted in the Hypo-RESOLVE project is essential for advancing our understanding of the impact of hypoglycaemia on quality of life in people living with diabetes.
Abbreviations
- CGM:
-
Continuous glucose monitoring
- EQ-5D VAS:
-
EuroQol-5D visual analogue scale
- Hypo-RESOLVE:
-
Hypoglycaemia – REdefining SOLutions for better liVEs
References
Henriksen MM, Andersen HU, Thorsteinsson B, Pedersen-Bjergaard U (2021) Effects of continuous glucose monitor-recorded nocturnal hypoglycaemia on quality of life and mood during daily life in type 1 diabetes. Diabetologia 64(4):903–913. https://doi.org/10.1007/s00125-020-05360-9
U.K. Prospective Diabetes Study Group (1999) Quality of life in type 2 diabetic patients is affected by complications but not by intensive policies to improve blood glucose or blood pressure control (UKPDS 37). Diabetes Care 22(7):1125–1136. https://doi.org/10.2337/diacare.22.7.1125
Speight J, Holmes-Truscott E, Hendrieckx C, Skovlund S, Cooke D (2020) Assessing the impact of diabetes on quality of life: what have the past 25 years taught us? Diabet Med 37(3):483–492. https://doi.org/10.1111/dme.14196
Bradley C (2001) Importance of differentiating health status from quality of life. Lancet 357(9249):7–8. https://doi.org/10.1016/s0140-6736(00)03562-5
Walters SJ, Brazier JE (2005) Comparison of the minimally important difference for two health state utility measures: EQ-5D and SF-6D. Qual Life Res 14(6):1523–1532. https://doi.org/10.1007/s11136-004-7713-0
de Galan BE, McCrimmon RJ, Ibberson M et al (2020) Reducing the burden of hypoglycaemia in people with diabetes through increased understanding: design of the Hypoglycaemia REdefining SOLutions for better liVEs (Hypo-RESOLVE) project. Diabet Med 37(6):1066–1073. https://doi.org/10.1111/dme.14240
Carlton J, Leaviss J, Pouwer F et al (2021) The suitability of patient-reported outcome measures used to assess the impact of hypoglycaemia on quality of life in people with diabetes: a systematic review using COSMIN methods. Diabetologia. https://doi.org/10.1007/s00125-021-05382-x
Authors’ relationships and activities
All authors are members of the Hypo-RESOLVE Consortium.
Author information
Authors and Affiliations
Contributions
All authors were responsible for drafting the article and revising it critically for important intellectual content. All authors approved the version to be published.
Corresponding author
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
About this article
Cite this article
Søholm, U., Broadley, M.M., Choudhary, P. et al. Does nocturnal hypoglycaemia really improve quality of life?. Diabetologia 64, 1893–1894 (2021). https://doi.org/10.1007/s00125-021-05475-7
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00125-021-05475-7