Three Layers of Glucose Testing Governance

Three layers govern how a glucose result reaches a chart, and each layer carries a different obligation. Waived testing is the simplest: the laboratory follows the manufacturer's current instructions for use exactly, with no modification to specimen type or procedure, and CLIA does not require the formal six-element competency assessment that nonwaived testing requires. Nonwaived point-of-care testing, which covers most hospital bedside glucose programs, adds that six-element competency requirement under a technical supervisor. CGM sits in a third layer with its own governance: no CGM system currently carries FDA marketing authorization for general inpatient use, so hospital use of a patient's personal CGM runs under an institutional protocol rather than a device-specific inpatient clearance.

ISO/TS 22583:2024 offers a useful frame for that third layer even though it is not a CLIA requirement. It describes a supervisor who holds authority and accountability for a point-of-care service's quality, timeliness, accuracy, and safety, and who may also serve as an operator if operator-level training and competency requirements are met. That supervisor-operator model maps cleanly onto a hospital CGM program: someone has to own device assignment, training, and data-integrity decisions, even when the device itself was cleared for outpatient use.

The same distinctions guide bedside action. Follow the current manufacturer instructions for a waived system, maintain the six-element competency framework for nonwaived POCT, and use the institution's approved protocol for inpatient CGM; that protocol specifies when and how CGM and point-of-care values are reconciled for the clinical decision.

2024 device clearances illustrate why the CGM layer is not interchangeable with the other two. Dexcom G7 and FreeStyle Libre 3 received clearances and label updates for outpatient diabetes management, and an over-the-counter category (Dexcom Stelo, Abbott Lingo and Libre Rio) was cleared for adults not on insulin for general wellness and glucose-awareness use. None of those 2024 actions covered a general inpatient hospital indication, and a consumer wellness device is a different regulatory category from both a prescription CGM and any laboratory test. Table 1 lists these devices against their cleared use.

The layer a test sits in determines the record you must keep, not just how the meter is physically used. Before trusting any glucose number at the bedside, know which of the three layers produced it.