I read somewhere that there is a link between erratic sleep and diabetes due to fluctuating BG levels! Since diagnosis In don't think I have had one decent night's sleep. I know this is a very common problem generally (BBC programme about sleep deprivation) but does any body have any practical advice. I am shattered day after day!

Yeah, I can relate to the symptom of interrupted sleep because of fluctuating blood glucose levels. I spent a year on sleeping tablets, which were unnecessary and didn't help in the long run. Getting to sleep wasn't the problem, it was staying asleep!
The hyper/hypo bouncing about does something to your subconscious and your REM sleep. The vivid realistic dreams were a constant reminder that something wasn't quite right.
For me, the answer lay in the solution to treating my condition and take away the symptoms. Going very low carb and losing weight, getting control of my blood glucose levels.
If I didn't get a decent nights sleep, it was awful!
REM and the next phase of sleep is so important to being refreshed and the healing and the brain functions are better.
So much benefit from a really good night's skip!
What helped me enormously was having a supper of Greek yogurt (full fat) and dark chocolate (85%) with a couple of berries. This somehow made my brain relax more and stopped my blood glucose levels bouncing around.
Once you get good control your sleep pattern should improve.
And don't forget, you have had a serious jolt to your system and a change in diet, so your body is not use to what you are doing and is probably rebelling against the fact you are trying to get yourself sorted.
Sweet dreams!