High blood glucose is a potentially dehydrating condition. One molecule of glucose needs to pair up with several water molecules, which is why people with diabetes need extra intake of water when their condition is not controlled. Dehydration in diabetes is often detected with an unusual thirst throughout the day, which is especially prevalent in patients with frequent urination.
It is an early symptom that would reappear in people with advanced diabetes, especially when they need an adjustment in their medications. Thirst is a natural reflex to dehydration, and there are many health problems associated with this condition, which is why it should not be taken as the only sign to watch out for diabetes.