A randomized controlled pilot study of continuous glucose monitoring and flash glucose monitoring in people with Type 1 diabetes and impaired awareness of hypoglycaemia

AimHypoglycaemia 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. MethodsA 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. ResultsSome 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(1c) 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 -4.3%, P = 0.006). Time spent in hypoglycaemia at all thresholds, and hypoglycaemia fear, were different between groups, favouring CGM. ConclusionCGM 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) What's new? This is the first head-to-head glucose monitoring study comparing continuous glucose monitoring (CGM) and flash glucose monitoring. This study addresses the highest risk group with problematic and severe hypoglycaemia. CGM has a greater beneficial impact on hypoglycaemia outcomes than flash glucose monitoring for people at high risk of hypoglycaemia. The data contribute to the existing CGM literature and are the first for flash glucose monitoring in a high-risk group, expanding the evidence base. The results are clinically relevant and support a role for CGM in the clinical pathway in people with severe hypoglycaemia or impaired awareness of hypoglycaemia.