Assessing glycaemic impact of FreeStyle libre monitoring in patients with insulin-treated type 2 diabetes: a retrospective real-world analysis

Objectives FreeStyle Libre (FSL) monitoring is available for all patients in Wales with insulin-treated diabetes. English guidance permits FSL in patients with type 1 diabetes mellitus (T1D) and type 2 diabetes mellitus (T2D) requiring multiple daily insulin doses (MDI) (National Institute for Health and Care Excellence 2023). The literature suggests benefits from using FSL, specifically improved glycaemic control and reduced hypoglycaemia. Methods Patients aged >18 years with insulin-treated T2D using FSL for >= 3 months were identified from Libreview. Those with pre- and post-FSL HbA1c were included. Days 1-14 of FSL data were taken as baseline. Patients were categorised by insulin regime (OD basal, premixed, basal bolus). Results 236 patients were identified and 189 patients included. The median follow-up duration was 14.6 [10.3-15.0] months. There were significant reductions in median HbA1c [8 mmol/mol, p < 0.001], time below range [< 4.0 mmol/L](1.2 +/- 3.4 vs 0.6 +/- 1.5%, p = 0.01), and low glucose average duration [52.1 +/- 77.3 vs 35.6 +/- 58.7 min, p = 0.01]. HbA1c improvements were greatest in OD basal [12 mmol/mol, p < 0.001] and pre-mixed [12.5 mmol/mol, p < 0.001] insulin regimes. Those taking premixed insulin had an increased time in target [7%, p < 0.05], reduced time above target [5.5%, p < 0.05] and reduced average glucose [0.3 mmol/L, p < 0.05] and GMI [2 mmol/mol, p < 0.01]. Patients on basal bolus insulin had significantly reduced time below range [0.5% p < 0.05]. Conclusions Improvements in HbA1c were greatest in those taking OD basal or premixed insulins. Reductions in hypoglycaemia are likely to positively impact quality of life. Further studies will elucidate whether these improvements are directly related to improved quality of glycaemic data facilitating closer treatment titration, or behaviour changes related to FSL use.