My situation is very similar to yours! 28, with a young family. Spent years drinking smoking and eating like a monster! (Plus not testign) SImply eating what I like and doing my best to counteract with insulin - a real co*k ar*ed way of dealing with it.
In two seperate instance ive been found to have the very begginings of complications.... minor changes in my eyes during retinopathy. And more recently, protein leaking from my kidneys.
For both things from intial finding and within 3 months of bucking up my ideas and getting under decent conrol I have to an extent reversed the damage (Definatly in the eyes) and intial evidence suggests I have on the kidneys (Ie less protein leaking and a reduced blood pressure).
Im not saying that in every instance it can be reversed nor that when these complications are found go on a health kick for a few months then back to normal life.
Im saying, keep up the screenings and appts. The earlier things are found the more treatable they are.
&
Healthier lifestyles and blood sugars are obviously better for you, ive definatly proved this to myself recently. This time I wont be reverting back to how I was. Ive kicked smoking, a lot of the drinking (Although ill still have a few every now and again) Ive lost 3 stones, Ive cut carbs from around 250g a day, to about 140g which has made managing my bloods a lot easier. I test a lot and im learning a lot about my body. I do still have a treat here and there, but to me would life be worth living without a chinese takeaway every now and again!!
It has been a really hard road, its taken a year to drop the 3 stone, and the hunger pains have killed me, exercise was never part of my life before, but now i try and play a bit of tennis, and do a lot of walking and stuff and its helped tremendously. I feel much better within my self now.
Good luck mate, itll be worth it, and congrats on the baba!