Hey Mike,
Sorry to read that you are now battling cancer on top of your diabetes.
Unfortunately, steroids are known to increase blood sugar levels.
Regarding the difference between Type 1 and type 2 - they are two different conditions which are not defined by the treatment.
Type 1 is an auto-immune condition where our bodies have decided they don't like the cells that produce insulin so have killed them off and we produce no insulin. Type 2 is where your body is resistant to insulin - it kind of "wastes it" so needs more which is why you are needing to inject extra insulin.
Therefore, you don't "become Type 1" due to a change of treatment or use of steroids. You still have type 2 diabetes.
It is possible to become insulin resistant and have Type 1 diabetes so there are some people, for example, who treat their condition with insulin and metformin.
And there are some people who are misdiagnosed so don't become Type 1 but their diagnosis is corrected to Type 1.
Good luck with your caner treatment. I hope it does not get you down too much.