Non-Invasive Glucose Monitoring (NIGM) aims to measure blood glucose without skin puncture, utilizing technologies like Near-Infrared (NIR) Spectroscopy, Raman Spectroscopy, and Reverse Iontophoresis. While NIR is the most researched modality, it struggles with signal interference from water and skin temperature. Historical attempts like the GlucoWatch failed due to skin irritation and calibration needs.

Currently, no NIGM device is FDA-cleared for insulin dosing. The core technical challenge is specificity: distinguishing the weak glucose signal from the "noise" of other tissue components. Recent trends involve integrating these sensors into consumer wearables (smartwatches), prompting the FDA to issue safety warnings in 2024 regarding the lack of accuracy in these consumer-grade devices compared to standard enzymatic test strips or minimally invasive CGMs.