text: Three variables of cardiac vagal effects (the root mean square of successive differences [rMSSD] in the interbeat interval of the heart rate [IBI], heart-rate variability [HRV] caused by peak-valley respiratory sinus arrhythmia [pvRSA], and high-frequency power [HF]) and heart rate (HR) were obtained at seven time points during the clamps, characterised by increasing levels of << insulin >> (achieved by administering insulin plus [[ glucose ]], glucose only, glucose and GLP-1, and glucose and GLP-1 combined with arginine).