Telomerase is the enzyme responsible for maintenance of telomeres, which are special capped structures that protect chromosomal ends from degradation. Telomerase activation and metabolic reprogramming have both emerged as hallmarks of cancer. Here, we investigated the link between telomerase and metabolism in mutant isocitrate dehydrogenase 1 (IDH1) glioma cells with the goal of identifying MR-detectable biomarkers of telomerase expression. Using 13C- and 1H- MRS, we show that telomerase expression is associated with elevated flux through the pentose phosphate pathway resulting in increased levels of reduced glutathione (GSH). Thus, GSH is a potential biomarker of telomerase expression in mutant IDH1 gliomas.