Plasma gastric inhibitory polypeptide and glucagon-like peptide-1 levels after glucose loading are associated with different factors in Japanese subjects

Aims/Introduction: Gastric inhibitory polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) are major incretins that potentiate insulin secretion from pancreatic beta-cells. The factors responsible for incretin secretion have been reported in Caucasian subjects, but have not been thoroughly evaluated in Japanese subjects. We evaluated the factors associated with incretin secretion during oral glucose tolerance test (OGTT) in Japanese subjects with normal glucose tolerance (NGT). Materials and Methods: We measured plasma GIP and GLP-1 levels during OGTT in 17 Japanese NGT subjects and evaluated the factors associated with GIP and GLP-1 secretion using simple and multiple regression analyses. Results: GIP secretion (AUC-GIP) was positively associated with body mass index (P < 0.05), and area under the curve (AUC) of C-peptide (P < 0.05) and glucagon (P < 0.01), whereas GLP-1 secretion (AUC-GLP-1) was negatively associated with AUC of plasma glucose (P < 0.05). The insulinogenic index was most strongly associated with GIP secretion (P < 0.05); homeostasis model assessment beta-cell was the most the strongly associated factor in GLP-1 secretion (P < 0.05) among the four indices of insulin secretion and insulin sensitivity. Conclusions: Several distinct factors might be associated with GIP and GLP-1 secretion during OGTT in Japanese subjects. (J Diabetes Invest, doi: 10.1111/j.2040-1124.2010.00078.x, 2011).