Laboratory assays
EMD
Arterialised blood samples were taken every 5 min during the hyperinsulinaemic–hypoglycaemic clamp; these samples were centrifuged and plasma glucose was analysed at the bedside by an enzymatic-amperometric method using chip sensor technology (Biosen C-Line GP+, EKF Diagnostics, Barleben, Germany). Additional samples taken at 30 min intervals were centrifuged within 1 h to separate the serum or plasma and stored at −80˚C before performing the following assays: insulin (Alpco, Salem, NH, USA; CV inter-assay 5.5%, intra-assay 6.4%), adrenaline (Alpco; coefficient of variation [CV] inter-assay 19.6%, intra-assay 14.3%), noradrenaline (Alpco; CV inter-assay 16.3%, intra-assay 12.0%) and glucagon (EMD Millipore, Burlington, MA, USA; CV inter-assay 15.7%, intra-assay 11%). Samples were analysed in duplicate according to the manufacturer’s instructions.