Calibration methods for Continuous Glucose Measurment Devices

Diabetes mellitus - a widespread disease. It is characterized by the inability of the pancreas to produce insulin (Type 1 diabetes) or by malfunctions in both insulin secretion and action (Type 2 diabetes). This means that a patient suffering from diabetes either cannot produce insulin to absorb glucose and turn into energy or cannot properly respond to insulin. A diabetic patient requires administration with exogenous insulin into the subcutaneous tissue. This thesis focuses on type 1 diabetic patients under insulin injection therapy. At present diabetic patients control their blood glucose level manually by measuring the concentration in blood collected from their finger tip several times a day to decide the amount of insulin dosage to be injected. The development of the continuous glucose monitor (CGM) was initiated with the hope that this new glucose measurement tool would enable signficant improvements in diabetes management. This shift to minimally invasive CGM primarily involves a shift from blood glucose measurements to devices measuring subcutaneous interstitial fluid (ISF) glucose. Interstitial glucose fluctuations are related to blood glucose presumably via diffusion process [10, 4]. This leads to a number of issues, including distortion (which incorporates a time lag) and calibration errors, and necessitates the development of methods for their mitigation. Different methods have been developed to describe the dynamics between ISF and blood glucose. A closer look is taken at the methods in order to change their sometimes very theoretical approach into a more practical orientated view. This includes the minimization of finger prick measurements as well as optimization for the use in patient’s life. Hence, the invaluable measurements should not only be used to control the CGM device but also to improve and update its signal.