Normal range is somewhere between 70-120 (this range can vary slightly depending on who you talk to, but I would say 70 is the lowest normal and 120 is the highest).
A blood sugar of 200 would be considered high.
Unfortunately (?) it is not immediately life threatening though. I say "unfortunately" because that makes it easier to ignore. You could theoretically go years with a blood sugar as high as 200 without ever knowing. It would cause damage to your organs and stuff overtime, and that would be bad*. (*Bad like my parent's friend who is diabetic and ignored his blood sugar for years and is now 1 leg lighter and has a freshly installed kidney from a car accident victim! lucky him. Seriously, he is not at all happy with his life choices at the moment. He ate cookies everyday for like 15 years and completely ignored his sugar. He felt "fine"."
The danger most of us who use insulin face is OVER COMPENSATING with TOO MUCH insulin.
Basically, the way I think about it, when a normal person eats, the body releases an appropriate amount of insulin to handle the carbs in the food. It releases just enough insulin to get the Blood Sugar (that was converted from the carbs eaten) to the cells for energy, but leaving enough in the blood (somewhere between 70 and 120) so things like your brain can function.
So if you go low, too low, you can pass out have a seizure, have a Steel Magnolias episode, pee your pants, see double, die, act like a damn fool, go into a coma, walk around your yard naked (I think I did that once), crash your car, not be able to add 2+2, make sense of simple things, get really, really agitated, etc....
Basically, act like your drunk without the fun. And possibly dying.
Those of us who have been around the block start experiencing these symptoms at lower levels. The body gets desensitized to it somehow. Sounds like a good thing but it isn't really, since it means we don't know we are close to death until we reach 28 instead of getting alerted at like 65.
Is it rare? no.
Is it dangerous? Yes, it can be.
Should you be afraid? Not if you are careful.
Am I being dramatic? Maybe a tad, but only a tad.
Test often (7-10x day)
get a pump (if you can afford it through insurance).
Learn to count carbs and learn you insulin-to-carb-ratio.
I have only been on a pump for 2 years (Jan 2007). I have been insulin dependent since 1987. I was 17 when I got it.
*acted like an idiot
*had a seizure, peed my pants, foamed at the mouth and dislocated my right shoulder (from the seizure) in front of my wife's family. Easter Dinner. I can laugh about it now..but HOLY CRAP!
*tried and failed to use an ATM machine to get moiney to buy a snickers bar because I couldn;t remeber how to use it.
*passed out at work and had 911 called for me
*almost crashed my car (guard rail woke me up as I started scraping against it)
Those are the Low-Lights. (vs high lights)
I was uneducated.
If he is on a pump, get the book "Pumping Insulin". It's great resource. If he is only taking shots, I would HIGHLY recommend getting a pump. Highly, highly, highly.
Hope I am not freaking you out. On a very serious note (another one), your bf's life is certainly not over by any means. I live a very full life and am very active. I do a lot of construction type stuff at my home, am very healthy in spite of diabetes, did karate for many years, etc...
I jut have to be more careful in the things I choose to do and how I do them.