A randomized controlled pilot study of continuous
glucose monitoring and ﬂash glucose monitoring in
people with Type 1 diabetes and impaired awareness of
M. Reddy, N. Jugnee, A. El Laboudi, E. Spanudakis, S. Anantharaja and N. Oliver
Division of Diabetes, Endocrinology and Metabolism, Faculty of Medicine, Imperial College, London, UK
Accepted 5 December 2017
Hypoglycaemia in Type 1 diabetes is associated with mortality and morbidity, especially where awareness of
hypoglycaemia is impaired. Clinical pathways for access to continuous glucose monitoring (CGM) and ﬂash glucose
monitoring technologies are unclear. We assessed the impact of CGM and ﬂash glucose monitoring in a high-risk group
of people with Type 1 diabetes.
A randomized, non-masked parallel group study was undertaken. Adults with Type 1 diabetes using a
multiple-dose insulin-injection regimen with a Gold score of ≥ 4 or recent severe hypoglycaemia were recruited.
Following 2 weeks of blinded CGM, they were randomly assigned to CGM (Dexcom G5) or ﬂash glucose monitoring
(Abbott Freestyle Libre) for 8 weeks. The primary outcome was the difference in time spent in hypoglycaemia (below
3.3 mmol/l) from baseline to endpoint with CGM versus ﬂash glucose monitoring.
Some 40 participants were randomized to CGM (n = 20) or ﬂash glucose monitoring (n = 20). The
participants (24 men, 16 women) had a median (IQR) age of 49.6 (37.5–63.5) years, duration of diabetes of 30.0 (21.0–
36.5) years and HbA
of 56 (48–63) mmol/mol [7.3 (6.5–7.8)%]. The baseline median percentage time < 3.3 mmol/l
was 4.5% in the CGM group and 6.7% in the ﬂash glucose monitoring. At the end-point the percentage time
< 3.3 mmol/l was 2.4%, and 6.8% respectively (median between group difference À4.3%, P = 0.006). Time spent in
hypoglycaemia at all thresholds, and hypoglycaemia fear, were different between groups, favouring CGM.
CGM more effectively reduces time spent in hypoglycaemia in people with Type 1 diabetes and impaired
awareness of hypoglycaemia compared with ﬂash glucose monitoring. (Clinical Trial Registry No: NCT03028220)
Diabet. Med. 35, 483–490 (2018)
Type 1 diabetes accounts for 10–15% of the worldwide
diabetes prevalence and its incidence is increasing worldwide
by 3–5% percent annually . Achieving optimal glucose
control, as measured by HbA
, reduces the risk of micro-
and macrovascular complications, but can be challenging for
people living with Type 1 diabetes due to hypoglycaemia
Hypoglycaemia is a metabolic complication of Type 1
diabetes and is one of the major barriers to optimizing
glucose self-management. People with Type 1 diabetes on
average have 1.8 self-treated incidences of hypoglycaemia
per week, and 0.2–3.2 episodes of severe hypoglycaemia,
deﬁned as hypoglycaemia requiring the assistance of a third
party, annually [5,6]. Recurrent hypoglycaemia erodes
hypoglycaemia awareness and impaired awareness is seen
in around a quarter of people with Type 1 diabetes .
However, this may be an underestimate, with self-reported
severe hypoglycaemia rates affected by driving regulations
and other considerations .
Impaired awareness of hypoglycaemia increases risk of
severe hypoglycaemia six-fold. Hypoglycaemia is one of the
postulated causes of the ‘dead in bed’ syndrome, which is the
Correspondence to: Nick Oliver. E-mail: email@example.com
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ª 2017 The Authors.
Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.