Effect of the glycemic index of carbohydrates on day-long (10 h) profiles of plasma glucose, insulin, cholecystokinin and ghrelin.
BACKGROUND
Low glycemic index (GI) carbohydrates have been linked to increased satiety. The drive to eat may be mediated by postprandial changes in glucose, insulin and gut peptides.


OBJECTIVE
To investigate the effect of a low and a high GI diet on day-long (10 h) blood concentrations of glucose, insulin, cholecystokinin (CCK) and ghrelin (GHR).


METHODS
Subjects (n=12) consumed a high and a low GI diet in a randomized, crossover design, consisting of four meals that were matched for macronutrients and fibre, and differed only in carbohydrate quality (GI). Blood was sampled every 30-60 min and assayed for glucose, insulin, CCK and GHR.


RESULTS
The high GI diet resulted in significantly higher glucose and insulin mean incremental areas under the curve (IAUC, P=0.027 and P=0.001 respectively). CCK concentration was 59% higher during the first 7 h of the low GI diet (394+/-95 pmol/l min) vs the high GI diet (163+/-38 pmol/l min, P=0.046), but there was no difference over 10 h (P=0.224). GHR concentration was inversely correlated with insulin concentration (Pearson correlation -0.48, P=0.007), but did not differ significantly between the low and high GI diets.


CONCLUSIONS
Mixed meals of lower GI are associated with lower day-long concentrations of glucose and insulin, and higher CCK after breakfast, morning tea and lunch. This metabolic profile could mediate differences in satiety and hunger seen in some, but not all, studies.
Reynolds
R C
RC
Human Nutrition Unit, School of Molecular and Microbial Biosciences (G08), The University of Sydney, NSW 2006, Australia.
Stockmann
K S
KS
Atkinson
F S
FS
Denyer
G S
GS
Brand-Miller
J C
JC
D000328:Adult; D001069:Appetite Regulation / Q000502:physiology*; D001786:Blood Glucose / Q000032:analysis*; D002766:Cholecystokinin / Q000097:blood*; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D002149:Energy Intake; D054439:Ghrelin / Q000097:blood; D038321:Glycemic Index / Q000502:physiology*; D006801:Humans; D007328:Insulin / Q000097:blood*; D008297:Male; D012528:Satiety Response / Q000502:physiology; D055697:Taste Perception / Q000502:physiology
D001786:Blood Glucose; D004040:Dietary Carbohydrates; D054439:Ghrelin; D007328:Insulin; D002766:Cholecystokinin