I definitely understand your blood sugar dilemma. For a couple things on that dilemma:
1.) Look up workout routines for athletes with diabetes. You might be able to find something worth looking into.
2.) Warm-up WELL since you have blood sugar issues. Same goes for your cool down.
3.) Try not to put yourself in a position where your head is below your waist (ie. decline bench, decline push-ups, handstands, etc.) for any prolonged period of time. It's one thing in yoga when you are doing a down-dog or something along those lines, but it's a bit different when it's a strenuous activity.
As for the knees and joint issue, try taking glucosamine, around 2000mg per day. Depending on where you are you can find it easily, or not so much. I know of some places online to find some too, if you would like those options. Some studies have show that taking 1000+mg of glucosamine repairs joint/ligament damage. This is controvesial a bit though, because it's only been shown to work sparadically, not on everyone. So it's worth a try. Glucosamine also isn't very expensive at all either.
Look into Darrin's E-Book in the store as well called "Solid Preformance." that should help supplement you in your form. Also, I know about 6 or 7 months ago Darrin, Greg, and myself had a rather long discussion on squat form/ flexibility on the forums. Look into that as well… http://worldfitnessnetwork.com…..r-a-while/
(related topic that might be helpful as well: http://worldfitnessnetwork.com…..-and-ufgs/)
We asl had a topic on workout nutrition, this may help with your insulin issues. I'm not informed too much about your diet, but I feel it's worth taking a look at. (http://worldfitnessnetwork.com…..kinny-guy/)
These are probably two of the best, most informational topics on the entire website. Be warned, they do get a bit in depth, so comment on them if you want us to elaborate. Other than that, hopefully it's a big help. And good luck.