Low fasting plasma glucose level predicts morbidity and mortality in symptomatic adults with congenital heart disease

BackgroundAdults with complex congenital heart disease (ACHD) have a high prevalence of abnormal glucose regulation (AGR: impaired glucose tolerance and diabetes mellitus). However, the impact of AGR on the prognosis remains unclear.PurposeOur purpose was to clarify the prognostic value of AGR in ACHD.Methods and resultsWe performed a 75 g oral glucose tolerance test in 438 consecutive patients with ACHD (age 26 ± 8 years), including 38 unrepaired, 148 Fontan, 252 biventricular, and 27 healthy subjects and investigated associations between AGR and clinical events that required hospitalization or caused deaths from all-causes. When compared with the healthy group, fasting blood glucose level (FPG, mg/dl) was lower in the unrepaired and Fontan subjects (p < 0.05-0.01) and the prevalence of low FPG (≤ 80 mg/dl) was also higher in the unrepaired (58%), Fontan (47%), and biventricular group (33%) than in the healthy control (11%) (p < 0.0001). Postprandial hyperglycemia (area under the curve of glucose: PG-AUC) was higher in all ACHD groups (p < 0.0001 for all). New York Heart Association class and lower FPG independently predicted the hospitalization (FPG ≤ 84 mg/dl) and mortality (FPG ≤ 80 mg/dl) (p < 0.05-0.0001), while the PG-AUC was not an independent predictor. When compared with the asymptomatic ACHD, symptomatic ACHD with lower FPG had high hazard ratios of 2.2 (95% confidence interval [CI]: 1.3-3.8, p < 0.002) and 3.3 (95% CI: 1.2-11.9, p < 0.03) for the hospitalizations and all-cause mortality, respectively.ConclusionsLow FPG is not uncommon in ACHD and the low FPG predicts the morbidity and all-cause mortality in symptomatic ACHD.