Acute plasma glucose increase, but not early insulin response, regulates plasma ghrelin.
OBJECTIVE
The independent role of glucose and insulin in ghrelin regulation is still controversial; this is also because in healthy subjects it is difficult to isolate the increase of glucose from that of insulin. The aim of this study was to discriminate the effect of glucose increase alone and early insulin response on plasma ghrelin, comparing ghrelin variation after i.v. glucose between healthy subjects and type 2 diabetic (T2DM) subjects, in whom the early insulin response to i.v. glucose is abolished.


METHODS
Plasma glucose, insulin and ghrelin levels were measured 0, 3, 5, 10, 30, 45 and 60 min after a 5 g glucose i.v. bolus in seven healthy control subjects and eight T2DM subjects.


RESULTS
There were no significant differences in body mass index, basal insulin and basal ghrelin between T2DM and healthy subjects. Basal glucose levels were higher in T2DM subjects than in controls. After i.v. glucose administration, plasma glucose increased significantly in both groups and the glucose peak was higher in T2DM subjects than in controls (9.67+/-1.25 (s.d.) vs 6.88+/-1.00 mmol/l, P<0.01). Insulin increased rapidly in controls, while in T2DM subjects, plasma insulin did not rise in the first 10 min. After the glucose bolus, plasma ghrelin showed a significant reduction both in controls and in T2DM subjects after 5 min.


CONCLUSIONS
These findings indicate that a low-dose i.v. glucose bolus reduces ghrelin both in controls and in T2DM subjects and therefore that early insulin response does not affect plasma ghrelin.
Department of Endocrinology and Metabolism, University of Genoa, Viale Benedetto XV 6, 16132 Genoa, Italy.
Lucia
L
Briatore
Gabriella
G
Andraghetti
Renzo
R
Cordera
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism*; D005260:Female; D054439:Ghrelin; D005947:Glucose / Q000493:pharmacokinetics; D006801:Humans; D007275:Injections, Intravenous; D007328:Insulin / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D036361:Peptide Hormones / Q000097:blood*
D001786:Blood Glucose; D054439:Ghrelin; D007328:Insulin; D036361:Peptide Hormones; D005947:Glucose