Related Experiment Video
Updated: May 26, 2026

Study of In Vivo Glucose Metabolism in High-fat Diet-fed Mice Using Oral Glucose Tolerance Test (OGTT) and Insulin Tolerance Test (ITT)
Published on: January 7, 2018
[Effect of different dietary loads on glucose-dependent insulinotropic polypeptide in subjects with normal glucose
Zhong Chen1, Li Yan, Xiao-ying Fu
1Department of Endocrinology, Guangdong Academy of Medical Sciences, Guangzhou, China. rosecz2004@yahoo.com.cn
Objective:
To investigate the secretion patterns of glucose-dependent insulinotropic polypeptide (GIP) after different dietary loads in subjects with normal glucose tolerance (NGT) and their relation to insulin secretion and plasma glucose levels.
Methods:
Fourteen subjects with normal glucose tolerance underwent 75 g glucose tolerance test(OGTT) followed by mixed meal tolerance test(MMT) one week later. Blood glucose, insulin, and GIP were measured in the fasting state and at 0, 15, 30, 60, 90 and 120 min after glucose load or mixed meal load.
Results:
The first peak value of GIP after glucose load occurred at 15 min (45.09∓4.67 pmol/L). After a brief decline, GIP continued to increase till reaching 59.66∓11.73 pmol/L at 120 min after the load. After the mixed meal load, GIP secretion presented with two peaks: the first peak appeared at 15 min (71.69∓14.19 pmol/L) with a level significantly higher than that at 15 min following glucose load (P<0.05), and the second occurred at 90 min (55.35∓13.19 pmol/L). The area under curve of GIP showed no significant difference between the two loads (P>0.05). Compared with glucose load, mixed meal load resulted in an increase of the first GIP peak and an earlier insulin peak (30 min vs 60 min), but a significant decrease of blood glucose at 15 min (P<0.05).
Conclusion:
Compared with glucose load, mixed meal (containing fat) can strongly stimulate GIP release and cause earlier occurrence of the insulin peak, which might be an important reason for the lower blood glucose after mixed meal.
Related Concept Videos
Hormones Regulating Blood Glucose
In addition to accelerating glucose uptake and utilization, insulin has...
Glucose Homeostasis: Pancreatic Islets and Insulin Secretion
Insulin and C-peptide are co-secreted in...
Insulin: Dosing Regimen and Adverse Effects
The basal dose constitutes about 40%-50% of the total daily dose, with the rest as premeal insulin. The mealtime insulin dose should mirror...
Glucose Homeostasis: Regulation of Blood Glucose
During fasting, when blood glucose levels are low, the pancreas secretes glucagon. it...
Glucagon-like Receptor Agonists
GLP-1, when administered in high doses intravenously, triggers insulin secretion, inhibits glucagon release, slows gastric emptying, reduces food intake, and restores normal insulin secretion. However, its rapid inactivation by the...
Dipeptidyl Peptidase 4 Inhibitors

