Yes, we could live as lo ng as the rest of the population, but basically it does reduce our life expectancy on average.
We do not heal as well, infections are more difficult to manage, the flu can kill us. It;s not cheery, but it is the truth. Diabetes is lifelong, and does recduce our life expectancy.
How could it not? High / low blood sugar swings, infection raising and making it unpredictable, severe lows, the way it complicates absolutely everything else.
I don't know about 20 years, but it does impact your general health in a negative way, it's just the truth, not gloomy, not depressing, it is just the way it is. You could live a slong as anyone else, there's nothing stopping that. But on average, we don't live as long.