Relationships of early and late glycemic responses with gastric emptying during an oral glucose tolerance test

Abstract

CONTEXT: The early glycemic response during a 75-g oral glucose tolerance test (OGTT) is directly related to the rate of gastric emptying (GE). There is little information about the effect of GE on the blood glucose at either 60 min (a predictor of diabetes) or 120 min (used diagnostically). OBJECTIVE: This study aimed to evaluate the relationships between glycemic responses at 30, 60, and 120 min and GE following a 75-g OGTT in subjects with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), and type 2 diabetes (T2D). DESIGN, SETTING, AND SUBJECTS: Eighty-two subjects in the general community without diabetes (57 NGT, 25 IGT) and 16 with T2D consumed a 75-g glucose drink labeled with (99m)Tc-sulfur colloid. GE (by scintigraphy) and glycemia were measured from t = 0-120 min and relationships between blood glucose (absolute, change from baseline, and area under the curve) and GE at 30, 60, and 120 min determined. RESULTS: There were no differences in GE. There were relationships between the blood glucose at 30 min and GE (NGT: r = 0.40; P < .01; IGT: r = 0.49; P = .02; T2D: r = 0.62; P = .01). There was also a relationship between the blood glucose at 60 min and GE in IGT (r = 0.52; P = .02) and T2D (r = 0.77; P < .01), but not NGT (r = 0.16; P = .24). In NGT, there was an inverse relationship between blood glucose at 120 min and GE (r = -0.30; P = .02), but not in IGT (r = 0.05; P = .82) or T2D (r = 0.37; P = .16). CONCLUSIONS: GE is a determinant of the glycemic response to an OGTT in NGT, IGT, and T2D but these relationships differ and are time dependent.