Docs don't always properly follow it and are often confused. It's supposed to be based on Dx not Tx criteria. Surely there is a better way.
For instance, I think I am T2 (or IDDM using an out-of-date term), or now "insulin-dependent T2". However, I see the doc used the diagnostic code 250.01 (T1) on various things, many times. Perhaps it's because my Tx is essentially identical to a T1 at this stage of the game, no matter if I should correctly be a T2 or not. The .01 part means "any T1 not stated as uncontrolled."
No need exists to tell us the hacknied and often repeated info on autoimmunity as evidenced by high reflex to titer of GAD-65, IA-2 or IAA as the essential feature distinguishing 250.01 from 250.00 since that is technically FLASE. T1's come in both types a and b, and GAD-65 antibodies are detected in 20% of diabetic twins who remain disease-free for long periods of time and in 8% of healthy individuals without DM. Plenty of autoimmunity aspects can be positively demonstrated in certain T2's of various type (just as for some people who do not progress to DM).
Are you pulling your hair out yet?