Abstract Non-compacted myocardium is a rare primary genetic cardiomyopathy described as an abnormality in endomyocardial morphogenesis where there is interruption of myocardial fiber compaction, generating a loose trabecular tissue. It is manifested with heart failure, embolism and ventricular arrhythmia. This is the case of systemic non-compacted cardiomyopathy in a 22-year-old woman, who had recently given birth and has type 1 diabetes mellitus.