Name a common sign of hyperglycemia.

Frequent urination, or polyuria, is indeed a common sign of hyperglycemia. When blood glucose levels rise significantly, the kidneys work to filter and excrete the excess glucose. This increased glucose in the urine creates an osmotic effect, causing more water to be drawn into the urine. As a result, the individual experiences the need to urinate more often, which can lead to dehydration if the fluid loss is not compensated by increased fluid intake. This symptom is often one of the earliest indicators of hyperglycemia, especially in individuals with diabetes.

While the other options present different symptoms related to bodily responses, they are not as directly linked to hyperglycemia as frequent urination. For example, excessive sweating could be a response to a variety of factors, including stress or hormonal changes. Increased appetite can occur in certain contexts but is not exclusive to hyperglycemia. Reduced energy levels can also be associated with a range of conditions, including metabolic issues or other health problems beyond just high blood sugar levels. Therefore, polyuria stands out as a key and common indicator of hyperglycemia.