Minor point on cakes - they have become established as a treat because at one time you had to save up to make or buy one. They used all sorts of expensive energy dense ingredients and so tasted really scrummy compared to "normal" food.
They are no longer a treat - couple of quid down the local supermarket - but they are still being viewed as a "treat".
Eating too much is not guaranteed to give you diabetes, but it does massively increase the risk.
What was that statistic - 80% of the obese don't get diabetes, but 80% of T2s are obese on diagnosis?
So being thin won't always protect you, being fat won't always condemn you, but your level of risk goes way up if you are over weight and wallowing in sweets and carbs.
Given that the Newcastle Study has shown that T2 symptoms can be reversed by weight loss we should not be encouraging people to over eat.