Glioblastoma is an aggressive cancer with a median survival of 16 months. Thus, waiting for changes in tumor volume to determine prognosis is too slow to benefit the patient. In this study, we show that in vivo measurements of tumor metabolism with hyperpolarized magnetic resonance can detect changes more rapidly and reliably than conventional anatomic MRI throughout all stages of tumor progression. These data are supported through ex vivo metabolic profiling. Interpretation of these results demonstrate the value that hyperpolarized magnetic resonance can bring to the clinic by addressing specific challenges encountered throughout the the care of glioblastoma patients.