A 17-year-old boy is brought to the pediatrician’s office by his parents who are concerned about their son’s weight loss despite eating more, frequent urination, unquenchable thirst, and fatigue that is interfering with his school/work activities. He had been seemingly healthy until about 3 months ago when his parents started noticing these symptoms but put these symptoms down to his busy schedule including a part time job. He admits to sleeping more and tires very easily. He denies any other symptoms.

PMH-noncontributory. No surgeries or major medical problems. Usual colds and ear infections as a child

Allergies-none know

Family history- maternal uncle with “some kind of sugar diabetes problem” but parents unclear on the exact disease process

Social-denies alcohol, tobacco or illicit drug use. Not sexually active. Junior at local high school and works in a fast food store after school and on weekends.

Labs in office: random glucose 220 mg/dl.

Based on his symptoms and the glucose level, the pediatrician makes a tentative diagnosis of Diabetes Mellitus type 1 and refers the boy and his parents to an endocrinologist for further work up and management plan.

Question 1 of 6:

The patient exhibited classic signs of Type 1 diabetes. Explain the pathophysiology of “polydipsia.”