Marked improvement in HbA1c following commencement of flash glucose monitoring in people with type 1 diabetes

Abstract

Aims/hypothesis: Minimal evidence supports the efficacy of flash monitoring in lowering HbA_1c. We sought to assess the impact of introducing flash monitoring in our centre.

Methods: We undertook a prospective observational study to assess change in HbA_1c in 900 individuals with type 1 diabetes following flash monitoring (comparator group of 518 with no flash monitoring). Secondary outcomes included changes in hypoglycaemia, quality of life, flash monitoring data and hospital admissions.

Results: Those with baseline HbA_1c ≥58 mmol/mol (7.5%) achieved a median -7 mmol/mol (interquartile range [IQR] -13 to -1) (0.6% [-1.2 to -0.1]%) change in HbA_1c (p < 0.001). The percentage achieving HbA_1c <58 mmol/mol rose from 34.2% to 50.9% (p < 0.001). Median follow-up was 245 days (IQR 182 to 330). Individuals not using flash monitoring experienced no change in HbA_1c across a similar timescale (p = 0.508). Higher HbA_1c (p < 0.001), younger age at diagnosis (p = 0.003) and lower social deprivation (p = 0.024) were independently associated with an HbA_1c fall of ≥5 mmol/mol (0.5%). More symptomatic (OR 1.9, p < 0.001) and asymptomatic (OR 1.4, p < 0.001) hypoglycaemia was reported after flash monitoring. Following flash monitoring, regimen-related and emotional components of the diabetes distress scale improved although the proportion with elevated anxiety (OR 1.2, p = 0.028) and depression (OR 2.0, p < 0.001) scores increased. Blood glucose test strip use fell from 3.8 to 0.6 per day (p < 0.001). Diabetic ketoacidosis admissions fell significantly following flash monitoring (p = 0.043).

Conclusions/interpretation: Flash monitoring is associated with significant improvements in HbA_1c and fewer diabetic ketoacidosis admissions. Higher rates of hypoglycaemia may relate to greater recognition of hitherto unrecognised events. Impact upon quality of life parameters was mixed but overall treatment satisfaction was overwhelmingly positive.

Keywords: Clinical Diabetes; Clinical diabetes; Continuous glucose monitoring; DKA; Devices; HbA1c; Human; Hypoglycaemia; Psychological aspects.

Fig. 1

Relationship between baseline HbA_1c and subsequent change in HbA_1c following flash monitoring. The grey shading indicates the 95% CI for the regression line. Spearman’s r −0.479, p<0.001

Fig. 2

Change in HbA_1c category pre- and post-flash monitor use; p<0.001, McNemar test for change, in both the <58 mmol/mol (7.5%) and the >75 mmol/mol (9.0%) categories. FM, flash monitoring

Fig. 3

Effect of exposure to flash monitoring on HbA_1c trajectory; p<0.001 for mixed effects model assessing interaction of time and flash monitoring category on log-transformed HbA_1c. Wilcoxon signed-rank comparison between 2016 and 2018: No FM, p=0.508; NHS FM after Mar 2018, p=0.008; NHS FM Feb/Mar 2018, p<0.001; Previous self-funded and NHS FM Feb/Mar 2018, p<0.001. FM, flash monitoring