Hi Tony
Personally I didn't really try fasting until I had cut down drastically on carb consumption. Once you become more fat adapted fasting becomes much less arduous. Then you are more likely to succeed.
Are you taking any medication? If so then you talk to your doc about stopping taking them while fasting or reducing dosage significantly.
I also haven't done a water only fast I always have tea and coffee when fasting with maybe some consommé to get some salt in me which is helpful. Also I wouldn't want caffeine withdrawal symptoms too while fasting! The most I have done is 5 consecutive days. When fasting I have had my best blood sugar levels so I do think it works well to reduce your levels.
If I can help in any other way let me know and also maybe take a look at the fasting section here..
http://www.diabetes.co.uk/forum/category/fasting.78/