ABSTRACTInfiltrative gliomas are the most common neoplasms arising in the brain, and remain largely incurable despite decades of research. A subset of these gliomas contains mutations in isocitrate dehydrogenase 1 (IDH1) or, less commonly, IDH2 (together called “IDHmut”). These mutations alter cellular biochemistry, and IDHmut gliomas are generally less aggressive than IDH wild-type (IDHwt) gliomas. Some preclinical studies and clinical trials have suggested that a ketogenic diet (KD), characterized by low-carbohydrate and high-fat content, may be beneficial in slowing glioma progression. However, not all studies have shown promising results, and to date, no study has addressed whether IDHmut gliomas might be more sensitive to KD. The aim of the current study was to compare the effects of KD in preclinical models of IDHwt versus IDHmut gliomas. In vitro, simulating KD by treatment with the ketone body β-hydroxybutyrate had no effect on the proliferation of patient-derived IDHwt or IDHmut glioma cells. Likewise, a cycling KD, wherein mice alternated between KD and a standard diet (SD), had no effect on the in vivo growth of patient-derived IDHwt or IDHmut gliomas, even though the cycling KD did result in persistently elevated circulating ketones. Furthermore, KD conferred no survival benefit in mice engrafted with Sleeping-Beauty transposase-engineered IDHmut glioma. These data suggest that neither IDHwt nor IDHmut gliomas are particularly responsive to KD.