Higher hemoglobin A1c levels are associated with impaired left ventricular diastolic function and higher incidence of adverse cardiac events in patients with nonischemic dilated cardiomyopathy.

We aimed to elucidate the relationship between glycated hemoglobin (HbA1c), cardiac systolic/diastolic function, and heart failure (HF) prognosis during guideline-directed medical therapy in patients with nonischemic dilated cardiomyopathy (NIDCM). We evaluated 283 hospitalized NIDCM patients, who were grouped according to baseline (BL) and 1-year (1Y) levels of HbA1c (<6.0, 6.0-6.9, and ≥7.0 %). The primary endpoint was defined as either readmission for HF worsening or cardiac death. Approximately half of the patients had BL- or 1Y-HbA1c ≥6.0 % (31 % at BL, 34 % at 1Y had 6.0-6.9 %; 12 % at BL, 12 % at 1Y had ≥7.0 %). The absolute value of left ventricular ejection fraction (LVEF) and its improvement during 1 year showed no significant difference among the 1Y-HbA1c groups (p = 0.273), whereas a lower absolute value and a more significant reduction in the early diastolic velocity of the mitral annulus (E a) were seen in the group with 1Y-HbA1c ≥7.0 % (both p < 0.001). In multiple regression analysis, higher 1Y-plasma B-type natriuretic peptide and lower 1Y-Ea were independently associated with higher 1Y-HbA1c (both adjusted p < 0.05). The cumulative incidence of the primary endpoint was highest in the group with 1Y-HbA1c ≥7.0 % (log-rank p = 0.001). Multivariate analysis demonstrated that higher 1Y-HbA1c was independently associated with a higher incidence of the primary endpoint (adjusted p = 0.005). In conclusion, hyperglycemia during clinical follow-up is a risk factor for progression of concomitant LV abnormal relaxation, leading to poor HF prognosis in patients with NIDCM.