Hyperpolarized lactate, pyruvate, alanine, and bicarbonate signal to sum of the signal ratios in controls and untreated and insulin-treated diabetic rats during inspiration of 66% and 10% oxygen in the inspired air. (Lactate-to-Σsignal) P < .001 for group* (between healthy controls and untreated and insulin-treated diabetic rats), P = .002* for treatment (inspired oxygen), and P = .0007 for interaction* (A). (Alanine-to-Σsignal) P = .43 for group (between healthy controls and untreated and insulin-treated diabetic rats), P = .15 for treatment (inspired oxygen), and P = .6 for interaction (B). (Pyruvate-to-Σsignal) P < .001 for group* (between healthy controls and untreated and insulin-treated diabetic rats), P = .002 for treatment* (inspired oxygen), and P = .05 for interaction* (C); (Bicarbonate-to-Σsignal) P = .1 for group* (between healthy controls and untreated and insulin-treated diabetic rats), P = .85 for treatment* (inspired oxygen), and P = .46 for interaction. Two-way repeated ANOVA (D).