A continuous glucose monitor tests interstitial fluid. The FreeStyle Libre 2 sensor is FDA-approved for wear on your upper arm. The Dexcom G6 sensor is FDA-approved for wear on your abdomen, upper buttocks or upper arm. CGMs do not require finger sticks, but they do require you to have the receiver/reader or a smart device nearby. CGMs can automatically collect and share glucose data and can predict dangerous highs and lows before they happen to help you stay within your target range.