title: Impact of incretin on early-phase insulin secretion and glucose excursion.
abstract: This study investigated the impact of incretin on early-phase insulin secretion and glucose excursion. The normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and type 2 diabetes mellitus (T2DM) groups included 16, 8, and 19 subjects, respectively. Subjects underwent continuous glucose monitoring for 3 days, followed by an oral glucose tolerance test. Plasma glucose, insulin, glucagon, total glucose-dependent insulinotropic polypeptide (GIP), and glucagon-like peptide-l (GLP-1) levels were measured at 30-min increments for 2 h after glucose intake. Differences with P < 0.05 were considered statistically significant. The area under the curve (AUC) of total GIP (120-min GIP-AUC) of the T2DM group was significantly lower than those of the NGT and IGT groups. The 120-min GLP-1-AUC of the NGT group was significantly larger than those of the T2DM and IGT groups. The early-phase insulin secretion index (ΔI30/ΔG30) of the T2DM group was significantly lower than those of the NGT and IGT groups. Mean amplitudes of glycemic excursions (MAGEs) went in the order of NGT < IGT < T2DM (P < 0.01, IGT vs. NGT; P < 0.001, T2DM vs. IGT). The 120-min GIP-AUC was negatively correlated with MAGE (r = -0.464), but uncorrelated with ΔI30/ΔG30. The 120-min GLP-1-AUC was positively correlated with ΔI30/ΔG30 (r = 0.580), but negatively correlated with MAGE (r = -0.606). Incretin may ameliorate glucose excursions, and GLP-1 may exert them by promoting early-phase insulin secretion. No correlation was observed between GIP secretion and early-phase insulin secretion.
authors.affiliation: Department of Endocrinology, The Third Affiliated Hospital of Southern Medical University, 183 Zhongshan Road West, Guang Zhou, 510630, People's Republic of China, shenjiedr@163.com.
authors.forename: Jie
authors.initials: J
authors.lastname: Shen
authors.forename: Zhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Chen
authors.forename: Xiao
authors.initials: X
authors.lastname: Zhu
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Han
mesh_terms: D000328:Adult; D001786:Blood Glucose / Q000378:metabolism*; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood; D005260:Female; D005749:Gastric Inhibitory Polypeptide / Q000097:blood; D005934:Glucagon / Q000097:blood; D052216:Glucagon-Like Peptide 1 / Q000097:blood; D018149:Glucose Intolerance / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D054795:Incretins / Q000097:blood* / Q000502:physiology*; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D008297:Male; D008875:Middle Aged
chemical_list: D001786:Blood Glucose; D054795:Incretins; D007328:Insulin; D005749:Gastric Inhibitory Polypeptide; D052216:Glucagon-Like Peptide 1; D005934:Glucagon