Nonsuppressed Glucagon After Glucose Challenge as a Potential Predictor for Glucose Tolerance

Glucagon levels are classically suppressed after glucose challenge. It is still not clear as to whether a lack of suppression contributes to hyperglycemia and thus to the development of diabetes. We investigated the association of postchallenge change in glucagon during oral glucose tolerance tests (OGTTs), hypothesizing that higher postchallenge glucagon levels are observed in subjects with impaired glucose tolerance (IGT). Glucagon levels were measured during OGTT in a total of 4,194 individuals without diabetes in three large European cohorts. Longitudinal changes in glucagon suppression were investigated in 50 participants undergoing a lifestyle intervention. Only 66-79% of participants showed suppression of glucagon at 120 min (fold change glucagon_120/0 <1) during OGTT, whereas 21-34% presented with increasing glucagon levels (fold change glucagon_120/0 ≥1). Participants with nonsuppressed glucagon₁₂₀ had a lower risk of IGT in all cohorts (odds ratio 0.44-0.53, P < 0.01). They were also leaner and more insulin sensitive and had lower liver fat contents. In the longitudinal study, an increase of fold change glucagon_120/0 was associated with an improvement in insulin sensitivity (P = 0.003). We characterize nonsuppressed glucagon₁₂₀ during the OGTT. Lower glucagon suppression after oral glucose administration is associated with a metabolically healthier phenotype, suggesting that it is not an adverse phenomenon.