Temporal Patterns of Glucagon and Its Relationships with Glucose and Insulin following Ingestion of Different Classes of Macronutrients

Background: glucagon secretion and inhibition should be mainly determined by glucoseand insulin levels, but the relative relevance of each factor is not clarified, especially followingingestion of different macronutrients. We aimed to investigate the associations between plasmaglucagon, glucose, and insulin after ingestion of single macronutrients or mixed-meal. Methods:thirty-six participants underwent four metabolic tests, based on administration of glucose, protein,fat, or mixed-meal. Glucagon, glucose, insulin, and C-peptide were measured at fasting and for300 min following food ingestion. We analyzed relationships between time samples of glucagon,glucose, and insulin in each individual, as well as between suprabasal area-under-the-curve of thesame variables (?AUCGLUCA, ?AUCGLU, ?AUCINS) over the whole participants' cohort. Results: inindividuals, time samples of glucagon and glucose were related in only 26 cases (18 direct, 8 inverserelationships), whereas relationship with insulin was more frequent (60 and 5, p < 0.0001). Thefrequency of significant relationships was different among tests, especially for direct relationships(p <= 0.006). In the whole cohort, ?AUCGLUCA was weakly related to ?AUCGLU (p <= 0.02), but not to?AUCINS, though basal insulin secretion emerged as possible covariate. Conclusions: glucose andinsulin are not general and exclusive determinants of glucagon secretion/inhibition after mixed-mealor macronutrients ingestion