Glucose concentrations in the body vary due to different rates of glucose utilisation by different body tissues. The varying rates of glucose utilisation may be due to varying amounts of muscle and fat tissue in parts of the body, muscular activity, and variations in blood flow. It is not known which of the sites reflects blood glucose values of greatest physiological significance with regard to managing diabetes. However, if a patient does experience differences greater than 20% between forearm and fingertip, the fingertip reading should be relied on as this is generally the location that has been used to establish doses of medication.