Mutant IDH1 (IDH1mut) drives glioma development, and targeted IDH1mut inhibitors show promising results in clinical trials. However, treatment is not associated with tumor shrinkage, and there is an urgent need for early imaging biomarkers of response. Our studies in IDH1mut-expressing glioma cells indicate that treatment with IDH1mut inhibitors leads to 1H and 13C-MRS-detectable metabolic changes. Specifically, we show a decrease in 2-HG and increase in glutamate, as well as an increase in metabolic flux from glutamine to glutamate. Furthermore, hyperpolarized [1-13C] α-ketoglutarate can probe these alterations in metabolism. This identifies potential non-invasive biomarkers of response to IDH1mut inhibition in glioma.