['To investigate the effect of glucocorticoid administration on leptin in humans.', 'A 30 min i.v. infusion of methylprednisolone (METH, 125 mg) or placebo (PLAC) followed by 4 d of oral administration of METH (40 mg/d) or PLAC. Fasting plasma glucose, free-fatty acids (FFA), insulin and leptin concentrations were measured at baseline, 210 min after the beginning of the i.v. infusion and after 4 d of oral treatment.', 'Twenty healthy non-diabetic male volunteers (27 +/- 5 y, 72 +/- 9 kg, 20 +/- 7% body fat; means +/- s.d.) fed a weight maintenance diet and randomly assigned to METH (n = 10) or PLAC (n = 10) treatment.', 'At baseline, leptin was positively correlated with % body fat in the 20 subjects (r = 0.53; P < 0.02). Acute METH administration significantly increased fasting plasma glucose (P < 0.01), but had no effect on insulin, FFA or leptin concentrations as compared to PLAC. Prolonged METH administration significantly increased fasting plasma insulin P < 0.05), but had no effect on glucose, FFA or leptin concentrations as compared to PLAC.'] Does acute and prolonged administration of glucocorticoids ( methylprednisolone ) affect plasma leptin concentration in humans?