In a diabetic patient, which sign should alert the nurse to a potential hyperglycemic episode?

Excessive thirst is a primary sign that can indicate a hyperglycemic episode in a diabetic patient. This symptom, known as polydipsia, occurs because high blood sugar levels cause the body to pull water from cells, leading to dehydration. When the kidneys filter excess glucose from the blood, they produce more urine, which can result in a loss of fluids and increased thirst as the body attempts to compensate for this fluid loss.

Increased energy is generally not associated with hyperglycemia; in fact, individuals with uncontrolled diabetes often feel fatigued due to the body's inability to effectively utilize glucose for energy. Drowsiness can occur but is not a definitive sign of hyperglycemia and can be related to other factors, including fluctuating blood sugar levels or complications of diabetes. Clear urine may indicate adequate hydration and normal kidney function, but it does not provide a specific indicator of hyperglycemia. Thus, excessive thirst is the most relevant and significant sign to watch for in this context.