1. The Affordable Care Act is supposed to take the burden off of emergency rooms - you're arguing for it, whether you mean to or not. In the USA, the situation you're describing is mostly past tense, except in states that have refused the expansion.
2. Treating the consequences of excess sugar consumption is not a huge burden fiscally. Diabetic care, even with insulin and multiple blood sugar tests per day. is fairly cheap (around $100 per month for the average patient - typically cheaper than non-generic antidepressants, and much cheaper than the average course of antipsychotics. The cost of treating marginal diabetic symptoms is usually 1 or 2 four dollar a month generic drugs and around 18 to 25 dollars in testing supplies, and probably $200 in lab tests and office visits a year. (That describes me, and the costs I might personally be passing on to the society if I was poorer). Those lab tests will usually also test for such things as prostate hormone levels and hypertension related cholestoral levels which may be at least vaguely connected to type 2 diabetes, but are not all that corollated. Doctors would still advise those tests for every male in my age range, and they have other tests they recommend for women in the same range, so all poor people above about age 40 would be passing a good share of such costs on regardless of their lifestyle choices.
3. Many diabetics do manage on these for over 20 years without further costs, and roughly 30% of diagnosed individuals manage to control their disease entirely through diet and exercise. (However, Type 2 often develops in elderly persons of normal weight - I assume we aren't counting them in the bad eating habits group). You probably are count ing me there - I first developed symptoms in my early 40's. Right now, I'm 57, stand 6' 1", weight 195 lbs, and hit the gym at least 3 times a week, usually 5. I can run a half marathon, bench 255 lbs. and leg press over 600, My resting heart rate is about 68 bpm, my blood pressure 110 over 72, and yet I still have to use Metformin and test 1x/day.But when I was first diagnosed, yes I had a bit of a gut, and yes I drank too many sodas. Sometimes what you're calling bad eating habits is one soda a week, and 15 lbs of excess fat. I'm making the choice to stay in better shape than 90% of the people my age, and that doesn't 'fix' my condition, only makes it much cheaper to treat and hopefully holds off any of the more severe consequences such as peripheral neuropathy.
So yes,their choices do have an effect on the people around them. So does just about everything. Do we require people to eat more cruciferous vegetables and less red meat? Treating colon cancer can be much more of a burden to society than diabetes. Or what about the social costs of a Down's syndrome child? These vary a lot, but particularly for single mothers and poorer class persons,can be devastating. If we just forcibly sterilized the at risk classes of mothers at about age 38, we could save a bundle. And the costs for a single violent schizophrenic can be in the 10's of millions when the disease leads to a school shootout. Talk about effect on the people around them! We can stop this by just putting all schizophrenics in institutions, and never mind that ones prone to major violence are very uncommon and we see the same type of violence from 'norma'l people.
4. I don't know who you are, but I guarantee you have some habit or practice that is your choice, and could, in the past, result in a tremendous cost to treat you. In the USA, unless you were making at least half a million a year, there were diseases that you couldn't possibly afford, and your insuror would stop covering when you hit your lifetime cap, often within the first year of a lifetime illness. This would still be true except for the Affordable Care Act's having stopped lifetime caps. You're protected there whether you like it or not, and so are the diabetics, choices or not.