IsCGMs

Intermittently scanned continuous glucose monitors (isCGMs) are a class of continuous glucose monitoring systems that provide glucose data primarily when the user scans the sensor with a reader or smartphone. The sensor is worn subcutaneously and measures interstitial glucose, storing data that can be retrieved on demand. Data typically displayed include the current glucose value, historical trend, and rate of change. Some isCGMs offer optional real-time alerts when readings exceed preset high or low thresholds, delivered via the reader or app.

Usage and operation: Users periodically scan the sensor to obtain glucose information. Sensor lifespans vary by device, commonly lasting one to several weeks. Many isCGMs are factory-calibrated and do not require fingerstick calibration, though requirements can differ by model and region. Data can be uploaded to digital platforms for review and sharing with caregivers or clinicians.

Comparison with real-time CGMs: Real-time CGMs (rtCGMs) transmit data automatically and continuously to a receiver or device and generally provide continuous alerts without scanning. isCGMs rely on deliberate scanning to retrieve data, with some devices offering optional alerts. Both types measure interstitial glucose and support diabetes management, but their data delivery and alert mechanisms differ.

Clinical use and benefits: isCGMs enable users to observe glucose patterns and trends, supporting adjustments to therapy, diet, and activity. When used consistently, they can improve time in range and help reduce hypoglycemia, particularly in adults with type 1 or type 2 diabetes and in settings where continuous auto-transmission is not essential.

Limitations: Data gaps can occur if scans are infrequent. Interstitial glucose lags behind blood glucose, and accuracy can vary with device, wear time, and user factors. Cost, access, and regional approvals may affect adoption.