I am convinced that thin T2 is one of 3 things. It could be misdiagnosed LADA (Latent Autoimmune Diabetes in Adults, a slow-onset form of T1), which could be proved by getting antibody tests (not that expensive), or it could be undiagnosed MODY (Maturity Onset Diabetes of the Young -- a monogenetic form of diabetes, which is neither T1 nor T2), which can be diagnosed by a strong family history and by genetic testing, although that's pretty expensive, and is not common, or it's another disease which hasn't even been noticed or described by the medical field. This type would be antibody and genetically negative, and so far as I can tell, NOTHING is known about it.
I've taken to calling the third form Type Weird, because it's NOT
classic T2, although it can affect people who are initially overweight
(not usually obese?) but when they lose significant amounts of weight, they observe no
improvement and sometimes worsening of their diabetes. T2 drugs sometimes work and sometimes
don't, and insulin is often the best choice of treatment, but as usual,
I personally have called myself Type Weird for years, because I'm
CLEARLY not classic T1 OR T2, and I never had the testing necessary to
confirm either LADA or MODY (and at this point, it's not worth it to
me). I was on Glucotrol, a sulfonylurea for 5 months and it did
absolutely nothing for me, and then I went on insulin and never looked
back, so I never tried metformin or any of the others, and at this point
refuse to do so, because I have enough GI problems as it is.
I had a coma in Sept. 2010, for various reasons, including major
depression, bingeing on sweets, and not taking enough insulin (i.e.
didn't omit it completely, but didn't take enough), and in the hospital,
the T2 protocols didn't work for me at all, and my BG was going up instead of down. The CDE had to fight with the hospitalist to get him to use T1
protocols. (There's no such thing as Type Weird protocols!). Then I
started getting better.
So, for reasons of safety, we decided that I should tell medical
folks that I'm T1, because I need T1 treatment protocols, regardless of
what else is going on medically. And in fact, my diabetes acts more like
T1 than T2, and so I'm comfortable with the oversimplification, even
though I KNOW it's not quite the whole picture. I truly don't fit
precisely into any of the known boxes, so I decided to go for proper
treatment, and not worry about labels. There are a LOT of different animals in the diabetes herd, even if the academics haven't figured that out yet.