I don't think it is a foregone conclusion you will be diabetic because of prednisone. I do think patients on prednisone should monitor their blood sugars for hyperglycemia.

I was on prednisone for 12 years and never reached the stage of diabetes. I was called prediabetic but my blood sugars weren't ever treated. My PCP "threatened" to start me on metformin if I wasn't careful.

In retrospect, I probably should have been treated with metformin. After I tapered off Prednisone my blood sugars stayed in the normal range. However, an endocrinologist checked my insulin level. My insulin level was very high and my endocrinolgist said it was only a matter of time before I would become diabetic had I stayed on Prednisone. My endocrinologist said I probably should have been on metformin the entire time I was on Prednisone to prevent insulin resistance.

I don't know what should be done but the following video provides some suggestions. Steroid induced diabetes is complicated but seeing an endocrinologist sooner rather than later might be a good idea,