Non‐invasive glucose sensors and improved informatics – the future of diabetes management

Modern diabetes care algorithms require the patient to take a very active role in day-to-day blood glucose management. Reduction of morbidity and mortality over the last 30 years in the population with type 1 diabetes are partially the result of improvements of insulin therapy based on capillary blood self-monitoring. Home glucose monitoring technology has made this clinical evolution possible. Enzyme-based ‘strip monitors’ provide the patient with the ability to determine capillary blood glucose level on demand. With proper training and a means to accurately determine blood glucose concentration, the patient with diabetes can effectively manage insulin or oral hypoglycaemic agent therapy. This approach has been validated on the basis of multiple outcome evaluations and linked to improvement of long-term objective markers of glucose concentration such as percentage haemoglobin A1c. The recent multicentre Diabetes Control and Complications Trial demonstrated that intensive insulin therapy based on multiple daily, self-administered capillary blood glucose measurements combined with periodic review by a health professional team resulted in better glycaemic control and improved outcomes. Patients with type 1 diabetes randomized to the intensive therapy group had lower mean blood glucose concentrations as evidenced by lower percentage glycosylated haemoglobin. More importantly, the incidence of chronic complications of diabetes associated with microvascular disease was significantly reduced [1]. Given the labile nature of blood glucose concentration, frequent sampling is required to detect hypo or hyperglycaemia and to effectively base insulin therapy. Unfortunately, blood collection by finger lancet is painful, inconvenient and messy. Consequently, patients with diabetes frequently fail to obtain data critical to their management. This observation coupled with the potential for blood glucose levels to rapidly fluctuate has led to extensive efforts in the biomedical industry to develop alternatives to the ‘finger puncture’ approach to selfblood glucose monitoring. These have included a variety of bioengineering efforts directed at minimally invasive, continuous in situ invasive and non-invasive instrumentation (table1) as well as alternate site blood testing. In each case, the objective has been to provide the patient with the means to make a higher frequency of daily glucose measurements with less personal discomfort. As the technology approaches this objective, four observations bear on the way new non-invasive monitoring and web-based informatics will impact diabetes care. First, it has become clear that the developing alternate site, non-invasive and minimally invasive technologies inherently sample glucose in tissue compartments other than the accepted standard of fingertip whole blood. The relationship of glucose concentration in compartments, such as the interstitial fluid, to glucose in the plasma compartment must be well understood to ensure that pharmacological and caloric therapy can be safely and effectively based on such measurements. Second, non-invasive monitoring techniques promise the possibility of easy access to glucose level monitoring away from home. As there is no risk of transmission of infection by blood or other bodily fluid, single centralized units would accommodate multiple users. Third,