Accuracy of Two CGM Systems Tested Simultaneously in Ambulatory Patients With Type 1 Diabetes

Each study patient will have both subcutaneous tissue CGM sensors inserted. Each sensor will produce a maximum of 1,440 tissue fluid glucose measurements per 24 hours and 8,460 measurements during the 6 days in study. The plan is to study 36 to 50 ambulatory patients during the hole study period. The two CGM data sets (DexCom4G and Medtronic Enlite) will be compared to each other and the time-matched reference blood glucose measurements. The HemoCue Analyser- venous blood and finger-stick blood in cuvette, will be used to measure the concentration of glucose. Each ambulatory patient will sample capillary blood and measure the concentration of glucose 6 to 10 times per day for max 6 days. The concentration of finger-stick capillary blood glucose will be measured using the HemoCue meter in their daily living and additionally a HemoCue Analyser at research visits using a lancet. Each patient will be admitted to the clinical research unit (CRU) for 7 measurements of venous samples at two occasions: on day 1-3 and 4-6 of the study with an interval of at least 15 minutes. An intravenous catheter will be inserted to facilitate blood sample acquisition each of these days of study. Three capillary finger-stick blood will be sampled at these 2 occasions, 1 at the first venous measurement (one day of days 1-3) and one at the last venous sample (one day of days 4-6). Blood sample acquisition and handling will be standardized to minimize pre-analytical error. The sensor insertion sites will be observed to detect bleeding, inflammation and infection of the skin or subcutaneous tissue. Insertion sites will be photographed if any abnormal findings exist at the end of the study for the individual patient. The subjects will record self monitoring of blood glucose (SMBG), meal, and activity data in a written diary.