GDF15 and diabetes mellitus: Elevated GDF-15 was associated with multiple characteristics indicating more severe HF (and worse outcomes) such as higher age, male sex, duration of disease, prevalence of diabetes, MI during the past 6 months, atrial fibrillation/flutter, poor kidney function, higher TnT and NT-proBNP levels and relevant for this population, lower iron, hemoglobin and transferrin saturation.