Which sign best indicates hyperglycemia when teaching signs of high blood sugar?

• A. Thirst
• B. Headache
• C. Nervousness
• D. Fruity breath odor

Answer: (D)

Fruity breath odor signals ketosis from very high blood glucose. When insulin is insufficient, the body shifts to fat metabolism, producing ketones like acetone that can be exhaled, giving a distinctive fruity smell. This sign is more specific to hyperglycemia (especially when ketosis is present) than thirst or headache, which can happen for many reasons, and nervousness is more typical of low blood sugar. So, the fruity breath odor is the most characteristic indicator of high blood sugar among the options.