Acute hyperinsulinemia is associated with increased plasma adrenomedullin concentrations in uncomplicated obesity

Objective: Adrenomedullin (AM) is a potent hypotensive peptide which may be implicated in the insulin regulatory system. Acute hyperinsulinemia exerts no influence on plasma AM in normal subjects while no data on obese subjects has been reported. Purpose: The aim of the study was to investigate the effect of acute hyperinsulinemia on the plasma AM concentration in patients with uncomplicated obesity. Research Methods: We measured the plasma AM levels in 23 obese subjects (BMI 41.9 +/- 9.8 kg/m(2)), 21 females and 2 males (mean age 31 +/- 7.2 years), before and during a euglycemic hyper-insulinemic clamp. The control group consisted of 43 healthy subjects (HS) (22 males and 21 females; mean age 38 12 years; BMI 23.3 +/- 3.2 kg/m(2)). Results: Baseline plasma AM was found to be higher in obese subjects (20.4 +/- 8.4pg/ml) than in normal subjects (11.3 +/- 0.8 pg/ml) (p < 0.001). A significant increase in the plasma AM levels was observed in obese subjects during acute hyperinsulinemia (from 20.4 +/- 8.4 pg/ml at 0 min to 26 +/- 8.9 pg/ml at 120 min, p < 0.02). Plasma AM concentrations were significantly correlated with insulin levels at 30 min (r = 0.44; p = 0.04) and 120 min (r = 0.40, p = 0.05) during the clamp. Discussion: In conclusion, acute hyperinsulinemia induced a significant increase in the plasma levels of AM in uncomplicated obese subjects. Hyperinsulinemia may, at least in part, regulate levels of AM in obesity, explaining the high levels of the peptide in these subjects.