Body tissues get dehydrated after the unnecessary loss of body fluids and electrolytes. This will make person feel thirsty. This condition is called polydipsia. It is one of the earliest and most common symptom of diabetes that you can not afford to ignore. Person feel that his mouth is dry for most part of the day which is commonly known as “cotton mouth”. The worst part of the problem is that the thirst may not go away even after drinking water.