Hi Rehl! Welcome to CWE.
We're a really friendly group, so feel free to ask questions, chime in , or vent in the padded room. Now, as for your two questions...First, yes, we do have some members who have children with autism who have seizures. I don't remember off the top of my head who they are, but I'm sure they'll be writing to you.
As for the second question, yes...blood sugar levels can trigger seizures.
I know this first hand. I have hypoglycemia as well as seizures. My blood level dropped down to 60 and caused me to have a seizure. That was how I found out that I was hypoglycemic. My mother's family also has a history of diabetes, so I try to be careful. If you think that hypglycemia might be triggering some of the seizures, try making sure that your son eats 6 times a day. Make sure that if he a carb (breads, pasta, potatoes, rice, anything with sugar in it) that he also has a serving of protein. When I say eat 6 times a day, I don't mean a whole dinner plate full. I'm talking about the amount that would fit on a dessert plate. Also, try getting rid of any processed foods (chips and snack foods in particular) in his diet, as well as weaning him off of any caffeine he might consume (coffee, tea, chocolate, cocoa, energy drinks...).
Just curious....you said your sons first seizure was when he was 14.....did the doctor's ever stop to consider that it was hormone induced? Some people see seizure activity at the onset of puberty and then outgrow them as they get older.
There is a higher incidence of seizures in people with Autism, but I think that you're right in wanting to know if anything else could have caused the seizures. Keep badgering his doctors. And if they won't talk to you, look for another neurologist. Just know that you might not find a reason. Some of us never know exactly why we have seizures. Whereas others can point specifically to high fevers while they were infants, head injuries, or other conditions. Also, try keeping a journal with everything he eats and drinks (when and how much), how much sleep he gets, any stress he might be under. Think back to the last seizures he had....what was he doing those days? Where did he have the seizures? Did he get enough sleep the night before? Looking back and seeing everything written out, you might notice a pattern. This will help you and the doctor figure out if there's anything in particular that triggers his seizures. Things such as flickering or strobe lights, hyperventilating, eating certain foods, household chemicals, etc... I hope this helped.
Check out the Epilepsy 101 link in my signature. It gives some great basic information about seizures.