Each subject participated in one experimental intervention. During the glucose clamp intervention, the subject's blood glucose was continuously monitored either by means of the Biostator or by frequent venous blood glucose measurements based on a standard lab method (YSI STAT2300 analyzer), and measured by means of the BD Technologies test devices, and the Medtronic Guardian CGM. Once the clamp was discontinued the Biostator was discontinued as well. During the unclamped period and meal the subjects BG was monitored via the YSI Glucose Analyzer, the BD CGM sensor and the Medtronic Guardian CGM.