Glucagon-like peptide-1 (7–36) amide response to low versus high glycaemic index preloads in overweight subjects with and without type II diabetes mellitus
Background and objective:Glucagon-like-peptide-1 (7–36) amide (GLP-1) is an insulin secretagogue and potential treatment for type II diabetes mellitus. An alternative to GLP-1 administration is endogenous dietary stimulation. We described a greater GLP-1 release following ingestion of liquids versus solids. We add to this work studying the effect of fluid preloads with differing glycaemic indices (GI) on the metabolic response to a meal.Subjects and design:GLP-1, insulin and glucose responses were measured in six overweight individuals and six subjects with type II diabetes on three occasions, after preload (milk, low GI; Ovaltine Light, high GI; or water, non-nutritive control) and meal ingestion.Results:In people with and without diabetes, the high GI preload produced the greatest glucose incremental area under the curve (IAUC)0–20, followed by the low GI preload, and water (P<0.001). In both groups, insulin IAUC0–20 was higher following high and low GI preloads compared with water (NS). In people without diabetes, the GLP-1 response was higher when high and low GI preloads were consumed compared with water (P=0.041), with no significant difference between nutritive preloads. GLP-1 response did not differ between preloads in people with diabetes. Despite initial differences, total IAUCs0–200 for biochemical variables did not differ by preload.Conclusion:We confirm that nutritive liquids stimulate GLP-1 to a greater extent than water in subjects without diabetes; however, this does not influence subsequent meal-induced response. The GI of preloads does not influence the degree of GLP-1 stimulation.