A 10-year-old patient in the pediatrician’s office has dropped from 65 pounds to 55 pounds since last seen in the office three months ago. The patient’s mother tells the nurse, “I just don’t understand how that’s possible. She eats constantly and is always thirsty. My other concern is that she has to urinate frequently; her teacher contacts me weekly to tell me she goes to the bathroom more than her peers.” The nurse anticipates this patient will be diagnosed with which condition?