They do require blood samples. The device sticks to the back of your arm, and a small sensor is embedded in your skin. It's painless, and the sensor continuousl

They do require blood samples. The device sticks to the back of your arm, and a small sensor is embedded in your skin. It's painless, and the sensor continuously samples the blood in your skin to measure blood sugar levels. They are accurate enough - they are FDA approved (in the US).