Biosensors for continuous glucose and lactate monitoring

Biosensors, and in particular glucose and lactate sensors, are being widely developed and a few have been registered for continuous and semi-continuous use. Three glucose sensors, a transcutaneous sensor (GlucoWatch), a needle sensor (MiniMed) and microdialysis sensor (GlucoDay) have recently been evaluated among diabetes patients. The precise relationship between the biosensor signal and blood glucose is still a problem. For example, the utility of the subcutaneously placed needle sensor to detect nocturnal hypoglycaemia has been shown to be limited. The best subcutaneous site for placing the sensor needs to be systematically investigated. The three types of sensors have only been tested for a 3-5 day period. The utility of the microdialysis (separate from a direct link to biosensors) sensors among diabetes patients was established over a 3-week period following subcutaneous implantation. Furthermore, biosensors are being developed to monitor lactate in preterm babies, and patients with ischaemia, sepsis, or threatened organ damage (e.g. heart and brain infarction). In view of the current progress it is expected that within 5 years biosensor technology will have developed far enough to be used in the management of diabetes and in intensive care units.