Glucose Clamp Study to Prove Hypo- and Hyperglycemic Episodes Using a Non-invasive Glucose Monitoring Device

• skin tissue glucose concentration [ Time Frame: continuously during the glucose clamp ] [ Designated as safety issue: No ]
  

• serum and urine electrolyte concentrations (sodium, potassium, chloride, calcium, magnesium, urea, osmolarity, pH, lactate, p(O2), standard bicarbonate, p(CO2), blood glucose concentration [ Time Frame: at 5 min intervals between the individual plateau phases, at 10 min intervals during the plateau phases (of the blood glucose concentration) ] [ Designated as safety issue: Yes ]
  

Device: Non-invasive CGMS (continuous glucose monitoring system)
A non-invasive continuous glucose monitoring device measure was applied at the wrist and measure skin glucose as an indirect measure of blood glucose every 10 min.
Procedure: Hyperglycemic and hypoglycemic glucose clamp
The automated glucose clamp technique was used to control glucose levels at baseline glycemia for 1h, hyperglycemia (300 mg/dL) for 1.5 h, and euglycemia (100 mg/dL) for another 1.5 h. A continuous somatostatin infusion was initiated after the 2 h run-in period to suppress endogenous insulin secretion. A glucose solution was infused to increase blood glucose towards the hyperglycemic target level. At the end of the hyperglycemic level the somatostatin infusion was stopped and blood glucose was controlled at the euglycemic target level. On a second study day a hypoglycemic clamp took place, where blood glucose after the run-in period of 2 h was lowered by means of intravenous insulin administration over a period of appr. 30 min to a hypoglycemic level of 45 mg/dL, where it was kept constant for appr. 30 min, after which blood glucose was raised to euglycemia (100 mg/dL) again by means of an intravenous glucose infusion and was kept there for 1.5 hours. .
Device: Non-invasive CGMS (GlucoDay)
The minimally-invasive glucose sensor GlucoDay, was used as a control measure

A completely non-invasive continuous glucose monitoring device is considered as a major target of glucose sensor development. The aim of this study is to evaluate the performance of a non-invasive glucose sensor (wristwatch) under controlled conditions (glucose clamp) at hyperglycemia (study day 1) and at hypoglycemia (study day 2). Measurements of the non-invasive glucose monitoring device are compared to those obtained from a minimally invasive glucose monitoring device (GlucoDay, microdialysis principle). In addition, changes in blood electrolyte concentrations as well as their impact on the measurements of the non-invasive glucose sensor are evaluated.