Effect of High- and Low-Glycemic Meals on Glucose Metabolism in Lean and Obese Adults Using 14C-Glucose Tracer

What this Trial Is About

Researchers are studying how the body processes glucose after eating meals with different glycaemic levels in healthy adults who are either lean or have obesity. The study focuses on the polyol pathway, which converts glucose into sorbitol and fructose, to understand if this pathway is more active after high-glycaemic meals and in people with obesity. This research aims to clarify how glucose metabolism varies between lean and obese individuals and how meal types affect this process. Participants consume either a high-glycaemic or low-glycaemic breakfast depending on their group assignment, followed immediately by a small oral dose of 14C-labelled glucose to trace glucose metabolism. Lean individuals are randomly assigned to either meal type, while those with obesity all receive the high-glycaemic meal. The study uses advanced Accelerator Mass Spectrometry to track glucose through various metabolic pathways with very low radiation exposure. Measurements include indirect calorimetry, blood and breath sampling, as well as collection of urine and stool over 72 hours to assess glucose oxidation, conversion, and excretion. During the study, participants spend about 12 hours in the lab on the first day and have shorter morning visits on days 2 to 4 for ongoing sample collection and assessments. Researchers measure energy expenditure, carbohydrate and lipid oxidation, plasma glucose and insulin levels, and tissue-specific glucose uptake using blood flow and metabolite balance techniques. The primary outcome is the total recovery of 14C-labelled glucose over 72 hours, providing detailed insight into glucose metabolism differences between lean and obese adults. The study lasts about 3 days in total for each participant.

How the Body Processes Sugar After Eating, in People With Different Body Weights