Hi DJFr33Dom,
I used to work in Dubai, I lived out in the region for two years - I know it's not quite KSA but there are some similarities.
Firstly, check to see if your job offer includes health insurance and that it covers pre-existing conditions. Most expat packages will include this and if you are getting supplies in the Middle East, you WILL need it or you can be looking at paying around ?400 a month for your supplies. Diabetes supplies are NOT cheap.
If your insurance packages does cover pre-existing conditions, check to see WHAT exactly it covers in terms of medication. My policy was terrible, it covered insulin and doctors' visits. However, it didn't cover needles or test-strips. And needless to say with the customer service in the region, pointing out to the insurance company that providing me with insulin but no actual way of using it seemed stupid simply drew a resigned shrug.
The good news is that everything you can get in the UK should be available in the Gulf. Diabetes is extremely widespread (around 30% of the population) and so they should have all the test strips, insulins, lancets and needles you need. For instance, I had no problems getting Lantus, Novorapid and Onetouch strips. These can also usually be bought over the counter as well, but again, it's expensive and you'll need a prescription if you want to claim back on insurance.
In terms of taking supplies with you - when I moved, I took about 6 months' worth of stuff in my hand luggage. Obviously I got stopped at the X-ray (I ALWAYS get stopped at the X-ray) and explained the situation. The security guy didn't even bat an eyelid and waved me through. You might want to take a doctor's note with you just in case though. And whatever happens, you must refuse to check this stuff into the hold. Not only will the temperatures in there damage your insulin...what are you supposed to do if your luggage goes missing?
You won't need to worry about keeping your insulin cool during the flight - insulin can survive at room temp for at least a month, so a few hours on the plane aren't going to hurt it. Make sure your accommodation has a fridge though and get that stuff in there as soon as possible after landing. Summer temps in Saudi reach up to 50C which isn't comfortable for you or your insulin.
One thing you also will need to read up on - mandatory Ramadan.
Yes, that's right.
In the Gulf countries, Ramadan fasting is mandatory, regardless of whether you're a Muslim or not. What that actually translates to is that during daylight hours, you aren't allowed to eat or drink in public. You can't even chew gum in public during daylight in Ramadan. As someone with diabetes, you are granted an exception under Islamic law from having to comply with this rule. HOWEVER, if a Saudi national sees you eating in public during the fast, they are going to assume you're an ignorant disrespectful Westerner, and explaining to the police that you have diabetes can be a bit tricky if you don't speak Arabic and they don't speak English. Play it safe. You can eat in your own home during daylight (provided you aren't right next to a window) but you can't eat in your car. In Dubai, many cafes and restaurants will have a fenced off area where non-Muslims can eat without offending those fasting. Some employers will also provide lunch areas as well to accommodate their non-Muslim staff. I'm not sure however whether this provision would apply in Saudi as they're a bit less flexible than the Emiratis. However, it may be that you'll be living in an expat compound, in which case you might have a lot more freedom within those walls.
Don't let any of the above discourage you. My decision to go to the Middle East was one of the best decisions I've ever made in my life and I'm sure it will be for you too. It is perfectly possible to manage your diabetes well out there and have a great time.