When we further divided the non-reduced LVEF cohort into the preserved LVEF and the mid-range LVEF cohorts, the peak VO2 and the AT VO2 were lowered in the diabetics in the LVEF 40-49% group, but not in the LVEF ≥ 50% group, after adjustment for age-squared, gender, anemia, renal function, LVEF, and log BNP (Additional file 1: Table S2). The gene discussed is NPPB; the disease is anemia (phenotype).