I am 17 years old and I have diagnosed autism; today I learnt that the average life expectancy for us is 39. I am about 48% of the way to being there and I have absolutely no idea how to feel about this; I've been laughing at it all day and I have no idea why. Some sources claim it is younger; 18 to 21 and I just don't even know how to feel.
I am not a doctor, but by a quick search on the net it seems that autism itself does not limit (at least not severely) lifespan. People with autism are just more prone to accidents. I take it that if you try to limit potential environmental risks you should be perfectly fine.