Which of the following is a symptom of hyperglycemia?

Hyperglycemia, or elevated blood glucose levels, is the primary symptom that indicates a problem with the body's ability to produce or respond to insulin. When blood glucose levels rise, the body attempts to bring them down, which may lead to other symptoms. However, the defining characteristic of hyperglycemia is indeed the high blood glucose itself. This particular symptom is critical for diagnosing and managing conditions such as diabetes, where persistent high blood sugar can lead to serious health complications.

While the other symptoms listed may occur in conjunction with high blood glucose due to various underlying issues, they do not specifically define hyperglycemia. Rapid heartbeat, dizziness, and cold sweats can be results of different medical conditions or hypoglycemic episodes and do not signify hyperglycemia directly. Thus, identifying high blood glucose as a symptom provides the most accurate indication of hyperglycemia itself.