What are the classic symptoms of Type 1 diabetes?

The classic symptoms of Type 1 diabetes include polyphagia, polyuria, and polydipsia.

Polyphagia refers to excessive hunger, which occurs because the body is unable to effectively use glucose for energy, leading to a feeling of constant hunger despite the intake of food. Polyuria is characterized by increased urination, which results from high blood glucose levels causing the kidneys to excrete more glucose into the urine, leading to a higher volume of urine. Polydipsia is excessive thirst that arises from the dehydration caused by frequent urination. These three symptoms are directly related to the underlying problem of insulin deficiency typical in Type 1 diabetes, where the body's cells cannot uptake glucose for energy, prompting these physiological responses.

Other choices reflect symptoms that may occur in different contexts but do not specifically represent the classic presentation of Type 1 diabetes. For example, weight gain and fatigue are often more associated with Type 2 diabetes or other conditions. Slow healing of wounds can occur due to various factors, not uniquely to Type 1 diabetes, while nausea and headaches may also have multiple causes unrelated to the classic diabetic symptoms.