Abnormal glucose metabolism in patients with Fontan circulation: Unique characteristics and associations with Fontan pathophysiology

Abstract Background Fontan patients exhibit a high prevalence of abnormal glucose metabolism (AGM). Purpose We aimed to characterize AGM and clarify its association with Fontan pathophysiology. Method and Results We prospectively evaluated AGM with plasma glucose dynamics [mg/dL; fasting glucose (FPG), and maximum glucose increase (PG-spike)] during oral glucose tolerance test (OGTT) and hemoglobin A1c (HbA1c) in 276 consecutive Fontan patients (aged 19 ± 7 years). Of these, 176 patients had serial AGM assessments with a mean interval of 6.5 years. Initial analysis revealed a high prevalence of impaired glucose tolerance (38.4%) and diabetes mellitus (DM) (4.7%), and positive family history, high HbA1c, and high central venous pressure independently predicted presence of DM. HbA1c was independently determined by hypersplenism and presence of DM (P  Conclusions AGM progressed even in young adult Fontan patients and HbA1c showed limited predictive value for progression. OGTT plays important roles in uncovering unique Fontan AGM as well as predicting all-cause mortality.