Ta1kin,
my mother is 5 foot 5, weighs 45 kg at the moment (she's been underweight most of her life, but this is lower than it has been for a long while. And yes, I'm worried about her).
She also has Type 2 diabetes.
All her own fault due to overeating?
Able to fix it merely by eating less?
By the way. I have Type 1. Had it for about thirty years now.
Which means I've spent way more time than I would like in endocrinologist's offices and waiting rooms. So other patients there will be both Type 1 and Type 2. And this is In the various countries I've lived in, which includes China, Japan, India, the US, the UK, America, and Germany. So places with a vastly differing range of what is normal body weight.
News flash: the VAST MAJORITY of my fellow diabetics that I saw were not overweight.
Some must have been Type 1, sure, but seeing as Type 2 make up approximately 90% of all diabetics, then surely a reasonable number of them would be Type 2.
In India, the clinic I visited was a free government clinic which treated everyone, this included people who were very very poor indeed, and who I doubt ever had a single chance in their lives to overeat. Didn't stop them getting Type 2!
The clinic was pretty open - no patient privacy - so you did end up hearing what the issues were with other patients.
(And yes, of course, there are also overweight more well-off Indians who get Type 2. But they are not the only ones)
There are all sorts of theories about the causes of Type 2.
One, for example, is that a foetus exposed in utero to maternal undernourishment is more likely to develop Type 2 in later life. This was developed looking at the development of children from times when there was abnormal restriction in food available, such as certain countries during the Second World War.
It is not as simple as you make out.