Using a hyperpolarized [1-13C]pyruvate tracer, we have shown that, following glucose ingestion, the myocardium increases pyruvate oxidation through PDH (PDH Flux), in line with the metabolic alterations proposed by the Randle cycle.6 In addition, we have also shown in patients with T2DM and diastolic dysfunction that PDH flux is reduced, similarly to alterations seen in animal models.7,20 This, therefore, represents the first noninvasive demonstration of physiological and pathological changes in PDH flux in the human heart using hyperpolarized MRS. This evidence concerns the gene PDP1 and type 2 diabetes mellitus.