Can doctors tell the difference between diabetes and starvation?

Yes for T2s, but most likely if we’re taking meds to lower our bloodsugar. We still get those random spurts of insulin from our pancreas too so it’s all a guessing game.

A quick blood glucose test will tell you what your blood glucose is; it will not tell you if you have diabetes. As others have mentioned, there are lab value criteria for that, and for differentiating type 1 from from type 2 (though it is not always black and white).

Also, by the time a diabetic’s breath smells of acetone, he or she is very ill and many other warning signs have probably gone unrecognized or were ignored.
mmm

it’s also no fun is when exercise raises blood sugar. It’s not particularly uncommon - and it’s an effect of stress hormones/action from the liver and exercising with not enough insulin on board. So it’s definitely a delicate balancing act.

Cite:
http://www.joslin.org/info/why_do_blood_glucose_levels_sometimes_go_up_after_physical_activity.html

Yeah, waiting until you see debris floating in the water is not a good way to find out that your ship is sinking.