Insulin, C-peptide, glucose, FFA, glucagon, cortisol, T3-free, T3-total, and urea concentration in serum were determined at examination days during basal and clamp conditions (t = 30 and t = 270, respectively).

Forearm blood flow, phenylalanine, tyrosine, urea and phenylalanine hydroxylation to tyrosine fluxes was measured at t = 210–240. Measurements were performed after an overnight fast of 10 hours (control) and after a 72-hour-fast (fasting). Values are means ± SE.