Insulin suppresses its own secretion in vivo.
This study addressed the controversial question of whether a negative-insulin-feedback loop exists in vivo. We utilized prehepatic insulin production, calculated by computerized deconvolution analysis of peripheral C-peptide concentration, as a measure of endogenous insulin secretion. Prehepatic insulin production was determined in 10 normal men who randomly underwent a control study and two additional studies involving different insulin infusion rates that achieved circulating insulin concentrations within the physiologic range during euglycemic clamps. The results demonstrate a dose-dependent suppression of prehepatic insulin production from 5.8 +/- 1.4 mU/min during the control study to 4.0 +/- 1.2 and 3.2 +/- 0.9 mU/min during plasma insulin levels of 34 +/- 4 and 61 +/- 6 microU/ml, respectively (P less than .05). Therefore, in contrast to recently reported results in vitro, insulin inhibits its own secretion in humans.
Argoud
G M
GM
Schade
D S
DS
Eaton
R P
RP
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D005246:Feedback; D006801:Humans; D007262:Infusions, Intravenous; D007328:Insulin / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D000078790:Insulin Secretion; D008297:Male
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin