Sorry to say, but cinammon only help type 2s. You'll find a lot of complementary therapies for diabetes are only actually for type 2s. Please don't be fooled into thinking that you can use something complementary to help him. Only insulin, a good healthy diet, exercise and looking after himself will help. I'm a type 1 diabetic (since I was 12, and I'm now 27) and I can honestly say that all you can do is keep working on those things. With a type 1 diabetic, our pancreas no longer makes insulin - there is nothing complementary that will replace that, only giving regular injections of insulin. As you're in the UK Martin, please look up DAFNE and see if there is a course near you, or look at diabetes UK website (a registered charity). They run some courses aimed at helping the whole family understand diabetes.
Hope this helps a little.
I seem to remember that there IS evidence that cinnamon helps lower blood sugars, but as I said it's only aimed at type 2s (which I think you are?). That's really interesting, though - how did you take it? I'm sure a lot of other type 2s will appreciate knowing that!