It seems that the smell of
urine is a strong indicator for diabetics, the
ammonia smell
in a diabetic is usually due to dehydration, so yes not drinking enough can be the reason for your urine smelling like ammonia. There are other causes too, and i would hope that it wasn't just assumed to be because you have diabetes and that you have had tests to rule them out eg urinary track infection.
This lists common causes http://www.buzzle.com/articles/ammonia-smelling-urine-in-women.