Trends of insulin pump therapy and continuous glucose monitoring use among people with type 1 diabetes by institution and region in Japan during 2014 and 2022: an observational study using nationwide claims data

AIMS: To describe national trends in insulin pump and continuous glucose monitoring (CGM) use among individuals with type 1 diabetes in Japan and examine variation by facility and prefecture. METHODS: We conducted serial cross-sectional analyses using Japan's National Database of Health Insurance Claims (FY2014-2022) and identified individuals with type 1 diabetes receiving regular care. Annual use of insulin pumps, sensor-augmented pumps (SAP), and CGM was quantified and stratified by facility caseload, Japan Diabetes Society certification, prefecture, and prefecture-level diffusion metrics. RESULTS: The study included 91,260 individuals in FY2014 and 119,104 in FY2022. Insulin pump use increased from 5.9% to 9.7%, SAP from 0.2% to 4.3%, and CGM from 0.2% to 39.8%. Uptake was higher in high-volume and certified facilities. Geographic variation persisted, and prefecture-level uptake was more closely associated with broader facility adoption than concentration of care. Trends around FY2020, particularly for CGM and SAP, should be interpreted cautiously because claims-based ascertainment changed following reimbursement revisions. CONCLUSIONS: In Japan, use of insulin pumps and CGM increased from 2014 to 2022, but pump uptake remained modest with persistent facility and prefecture variation. Broader adoption across care settings may be important for reducing variations in diabetes technology use.