Analytical Methods
Plasma glucose concentration was measured at the bedside using the YSI 2300
STAT glucose analyzer (YSI Inc., Yellow Springs, OH). Plasma free insulin concentration was measured by radioimmunoassay after polyethylene glycol
extraction of antibodies (15) using a commercial kit specific for human insulin
(Human Insulin-Specific RIA, DRG Diagnostics GmbH,Marburg, Germany).