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

Background

Adults 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.

Purpose

Our purpose was to clarify the prognostic value of AGR in ACHD.

Methods and results

We 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.

Conclusions

Low FPG is not uncommon in ACHD and the low FPG predicts the morbidity and all-cause mortality in symptomatic ACHD.