Polyuria and polydipsia may occur with high blood glucose levels (hyperglycemia), usually exceeding 250 mg/dl. Excess glucose spills into urine, drawing water along with it. Subsequently, the large amounts of urine produced (polyuria) also lead to an increase in thirst (polydipsia).  Polyphagia or increased hunger, as seen with diabetes, occurs with a lack of functioning insulin. Your body cannot use glucose without insulin and is hungry for more energy.