hun, am hoping the results come back negative, hopefully no matter the outcome you can find a way to manage his symptoms and get him back to 'normal' asap.
FWIW hun if it is Type 1 diabetes there is NOTHING you could have done, no diet or exercise regime would stop him getting it.
Again just hoping everything comes back negative and you can find whatever else may be causing it.

Just a bit of info re: TYPE 1 & TYPE 2
Type 1 diabetes differs from type 2 diabetes in several important ways. Type 2 diabetes is a metabolic disease where the body still produces some insulin but is not able to use it properly. It can often be managed with diet and lifestyle changes, though insulin is sometimes required. Type 2 diabetes affects more people – around 700,000 Australiansvi - usually those in middle age or beyond.
Once a patient is diagnosed with type 1 diabetes, which cannot be prevented, they will need lifelong insulin therapy to stay alive. - Taken from the JDFR Fact Sheet