Flash glucose monitoring compared to capillary glucose levels in patients with diabetic ketoacidosis; potential clinical application.

Objective Frequent, usually hourly, finger-prick capillary blood glucose measurement is standard care, used to drive insulin infusion rates for inpatients being resuscitated from diabetic ketoacidosis (DKA). Over recent years, there has been a shift towards continuous interstitial glucose monitoring (CGM), allowing monitoring of glucose without repeated invasive testing. Whilst CGM has been safely and reliably utilised in the outpatient setting, it has yet to be studied in acutely unwell, DKA patients. The aim of this study, allowing for physiologically lower interstitial compared to capillary glucose, was to determine if interstitial flash glucose monitoring (FGM) would lead to similar insulin infusion rates to capillary blood glucose (CapBG) in DKA. Methods This study took place at a metropolitan tertiary centre in South Australia, during 2019 and early 2020. Ten patients with diabetes mellitus, assessed to be in DKA were enrolled. At the same time as standard DKA management commencement, simultaneous FGM measurements were obtained using FreeStyle Libre Sensor applied to patients' upper arms. Duplicate paired glucose readings were then analysed for agreement using Bland-Altman plots and regression analysis for glucose measurements and resultant actual capillary glucose driven and predicted FGM driven insulin infusion rates. Results Actual (CapBG driven) and predicted (FGM determined) insulin infusion rates were similar, allowing for a standard correction of 2mmol/L for FGM testing, in patients in DKA without hypotension. Minor differences in predicted insulin infusion rates were noted in 2/10 patients at higher glucose concentrations and may relate to the lag in change in glucose in the interstitial space, but it is likely that standard frequent insulin infusion rate adjustments would prevent any alteration in clinical outcomes. Conclusion Based on our results, a trial of clinical outcomes in DKA patients treated with insulin infusion rates driven by CapBG vs subcutaneous FGM appears justified. FGM method of testing may improve patient comfort, obviate fatigue, improve staff time and direct patient contact and potentially facilitate rapid discharge.