Diabetic patients experience what is known in the medical field as polydipsia and it is basically marked by excessive thirst. It is a side effect of hyperglycaemia
Polydipsia in diabetics stems from the poor control of blood sugar in a person's body. The kidneys are at the center of this and when there's excess sugar in blood, the kidneys might not be able to keep up and as such, they end up producing more urine than normal. This results in dehydration and of course, excessive thirst.
I'd doesn't matter what type of diabetes you have, as long as your blood sugar is high, there's a good chance that you're going to experience some level of polydipsia.