CGM Device Guide
FreeStyle Libre 2 and 3
A nine-year-old back at school for the first week wearing a Libre 3, the sensor barely visible under her shirt sleeve. Her mum’s phone buzzes at 2.14pm: a downward arrow into the high fours, mid-afternoon, from a sandwich half-eaten at lunchtime. By 2.17pm the LibreLinkUp app shows treatment in and the trace climbing back. Mum doesn’t ring the school. The day continues. That trio, the smallest sensor on the market, the family-following app, and the family that learns to act on a distant arrow without panicking, is the Libre’s day-to-day signature.
Ask Grace
Want to ask which Libre version pairs with which AID system, or how to set LibreLinkUp up for school or a carer? Ask Grace.
Framework status
Data sufficiency: Met. Vaughan et al. 2025, Diabetes Technology and Therapeutics, meta-analysis of a decade of Libre accuracy studies; Abbott 2022 Libre 3 pivotal underpinning the 93.4% headline.
Device specifications
The headline numbers sit in the framework card above. The full device profile across the family is here for anyone who wants the detail.
Full device profile
Manufacturer: Abbott. Family: FreeStyle Libre 2, Libre 2 Plus, Libre 3, Libre 3 Plus. Wear duration: 14 days (Libre 2, Libre 3) or 15 days (2 Plus, 3 Plus). ±20/20 agreement: 93.4% (Libre 3 pivotal); approximately 93% across the family. Outside ±40/40: below 0.1%, the lowest in the GNL cluster outside Eversense’s annual implant. Calibration: not required, not accepted; if a reading does not match symptoms, a finger-prick is the correct next step. Reading method: scan-on-demand by NFC (Libre 2 family) plus Bluetooth alarms; continuous Bluetooth every minute (Libre 3 family). Display: LibreLink app on iOS and Android; optional dedicated reader on Libre 2 family only. Indication: non-adjunctive (no confirmatory finger-prick required for insulin dosing). Age indication: 4 years and older for the original Libre 2; 2 years and older for Libre 2 Plus, Libre 3, and Libre 3 Plus.
Size, the headline distinction. The Libre 3 (and Libre 3 Plus) is the smallest CGM commercially available, more than half the size of the Libre 2. The Libre 2 family is, by physical footprint, larger than the Dexcom G7. For anyone whose priority is discreet wear or skin real estate, the 2 and 3 are not interchangeable choices.
Accuracy
The number that matters is the ±20/20 agreement rate, the proportion of CGM readings close enough to laboratory truth to dose insulin from without a finger-prick. For the Libre 3, that figure is 93.4% in the pivotal study (Abbott 2022, summarised within Vaughan 2025, Diabetes Technology and Therapeutics). The Libre family also carries the lowest published rate of readings outside the ±40/40 safety band of any patch CGM in the cluster, below 0.1% across the generations. The full thesis on what these numbers mean, and on the small fraction of readings where errors become clinically large, lives on the accuracy page.
AID system compatibility
The Libre family looks the same on paper across generations. AID compatibility tells a different story: the partnership splits across the two form factors.
One family, two AID lanes. The Libre 2 Plus is the Abbott sensor for Omnipod 5. The Libre 3 (and 3 Plus) is the Abbott sensor for CamAPS FX on YpsoPump. Same chemistry, same algorithm, two different AID partnerships. Neither pairs with Tandem Control-IQ or the MiniMed 780G; the 780G runs its own three-sensor ecosystem, and the Abbott-made Instinct sold inside it is not the consumer Libre.
For people on Omnipod 5, the Abbott option is the Libre 2 Plus. For people on CamAPS FX, the Libre 3 (or 3 Plus) is the partnered sensor. For people on Tandem t:slim X2, the Abbott family does not yet pair, the Dexcom G7 is the AID-paired CGM for that pump. For people on the MiniMed 780G, the Abbott-made Instinct is the in-system sensor; the consumer FreeStyle Libre is not interchangeable with it.
What the Libre brings beyond accuracy
Libre 3, the smallest sensor
The Libre 3 (and 3 Plus) is the smallest CGM commercially available, more than half the size of the Libre 2 and noticeably smaller than the Dexcom G7. For people who notice their device, who train, swim, or live with eyes on the sensor, this is a real-world step change rather than a marketing line.
Continuous Bluetooth, no scanning
The Libre 3 family pushes a glucose value to LibreLink every minute over Bluetooth, no scan needed. The Libre 2 family uses Bluetooth for alarms and NFC scanning for the live reading. Both are valid; the Libre 3 workflow is the one that suits passive monitoring overnight, during exercise, and during the school day.
LibreLinkUp, the family-following app
LibreLinkUp gives parents, carers, school staff, and clinical teams a real-time view of glucose data from a connected Libre. It is the feature most often named first in paediatric clinic when families talk about what changed for them. From age 2 in the Libre 2 Plus, Libre 3, and Libre 3 Plus, this is the supported workflow.
LibreView Pro, into clinical records
LibreView Pro pulls Libre data into SystmOne and EMIS as SNOMED-coded entries, time in range, GMI, and average glucose appearing inside the clinical record without switching windows. As CGM use grows in primary care for insulin-treated type 2 diabetes, this matters for audit and the way reviews are run.
The hypo-event recording quirk
LibreView records a low-glucose event only when the trace stays below 3.9 mmol/L for 15 minutes or more. People who treat hypos quickly may have lived events that never appear on the report. The minute-by-minute trace will still show the dip, the event log will not. Worth knowing when the download and the lived experience disagree, and worth flagging when reviewing data with a diabetes team.
Survive and Thrive, FreeStyle Libre
A one-page A4 resource for the first two weeks on the Libre family. Sensor placement, scan-vs-stream workflow, alarms, LibreLinkUp setup, and the everyday habits that keep accuracy where it should be.
Device 2 of 5
FreeStyle Libre 2 and 3