Many diabetics have to go to the loo frequently as that is part of the body's attempt to get rid of the excess glucose. Consequently, they also have to drink a lot of water. However, if you have to get up nights, you tend not to drink the water and become a bit dehydrated, rather like alcohol acting as a diuretic. I feel a little like that every morning but always have a soluable fizzy vitamin tablet in a large glass of water, my alka seltzer alternative. It soon passes. I am also dieting and that too has a similar effect. As fats break down and lots stuff gets put in the bloodstream, you need to urinate it out. Most diets tell you to keep well hydrated but that's not so easy at night, at least if you want a good night's sleep.