Many cancers do feed on glucose - brain, lung, lymphomas, just to name a few. But, all cancers aren’t the same.
Those cancers are known to gobble up glucose (sugar), which is why the F18-FDG (Fluoro-2-Deoxyglucose) PET/CT scan worked so well detecting brain cancers, but was totally worthless detecting early/mid-stage prostate cancer. Prostate cancer feeds on testosterone.

As prostate cancer becomes more aggressive, metastasizes, or develops castration resistance, then prostate cancers find an alternative food source (and the F18-FDG PET/CT scan better detects prostate cancers).

Drs Scholz and Moyad touched on this topic at a 2019 PCRI conference: https://youtu.be/-PyqazlkpCE

It’s not a bad sign; they simply understand the nature of the prostate cancer they’re dealing with and are going after it appropriately.