Illustration of a continuous glucose (sugar) monitor (CGM, blue) attached to a patient's skin. This device measures the levels of glucose (orange) in the interstitial fluid (yellow), the fluid around the cells (pink), rather than in the blood (red). Diabetics have to measure their blood glucose levels regularly. A CGM can provide measurements, which are transmitted wirelessly, as often as once per minute without the need for a finger prick. For a labelled version of this image see F037/3466.