A possible connundrum

I am pretty active in the diabetes world here in England and as such, I get to meet and hear from loads of diabetics. Lately, I have encountered several young T2s. These were not the stereotype obese kids, but all of normal weight. they include a pair of identical twins diagnosed aged 12.
That made my brain cells get into gear.
Until recently, diabetes was classified by the age of the patient at diagnosis, ie juvenile onset, or adult onset. Nowadays we classify according to aetiology. Or as in Britain, assumption, based on the age of the patient. In Britain anyway, type isn’t usually determined by testing.
In the last few months too, I have come across newly diagnosed Adults, who were assumed to be T2s, but the diagnosis had to be revised when T2 treatment failed and they became ill, sometimes VERY ill ( DKA)
Now if children are thought always to be T1, they will be treated with insulin from the outset. this treatment won’t bring the mis-diagnosis to light and it will be assumed to be correct.
The thought I had was: how many children were always T2 and the medical profession didn’t realise it?
T2 diabetes may be even more common that was thought and T1 even rarer.
If it is related to an errant allergic response, as shown recently in mice. the researchers may be looking in entirely the wrong places to find how to reduce the number of cases.
I’m even more interested in this aspect of the condition, because I believe that T2causes weight problems, rather than being caused by them and I also have 2 very rare allergies( cold and vibration)