m thinking that you should take him to his pediatrician and have his blood tested, especially with a family history of diabetes. Another typical symptom that goes along with the increased
thirst is
frequent urination. If you have noticed this also, make sure you mention this to the doctor along with the irritability you mentioned in your posting. If it is diabetes, the sooner he gets treatment, the better it will be for him both physicially and emotionally (for everyone involved!).