IntroductionThis study aims to estimate the budget impact of increased uptake of the FreeStyle Libre Flash Glucose Monitoring system in people with type 1 diabetes mellitus (T1DM) in the UK.Research design and methodsA budget impact model was developed, applying real-world data collected in the Association of British Clinical Diabetologists (ABCD) FreeStyle Libre Nationwide Audit. Costs of diabetes glucose monitoring in a T1DM population (n=1790) using self-monitoring of blood glucose (SMBG) or the FreeStyle Libre system were compared with a scenario with increased use of the FreeStyle Libre system.ResultsThe ABCD audit demonstrates FreeStyle Libre system use reduces diabetes-related resource utilization. The cost analysis found that higher acquisition costs are offset by healthcare costs avoided (difference £168 per patient per year (PPPY)). Total costs were £1116 PPPY with FreeStyle Libre system compared with £948 PPPY with SMBG. In an average-sized UK local health economy, increasing FreeStyle Libre system uptake from 30% to 50% increased costs by 3.4% (£1 787 345–£1 847 618) and when increased to 70% increased by a further 3.3%.ConclusionIncreased uptake of the FreeStyle Libre system in the T1DM population marginally increases the cost to UK health economies and offers many system benefits.