Diabetes Defined by Hyperglycemia

Steps:

• Recall diabetes mellitus as a metabolic disorder impairing blood glucose regulation due to insulin issues.
• Identify key diagnostic sign: elevated blood glucose levels above normal thresholds (e.g., fasting >126 mg/dL).
• Distinguish from secondary effects like spillover into urine when blood levels exceed kidney reabsorption capacity.
• Eliminate options unrelated to core pathology, focusing on direct indicators.

Why B is correct:

• Diabetes mellitus is diagnosed by hyperglycemia, where blood glucose exceeds 200 mg/dL randomly or meets fasting criteria, per WHO/ADA definitions.

Why the others are wrong:

• A: Glucose in urine (glucosuria) is a symptom from overflow, not the primary diagnostic sign.
• C: Insulin is normally present in blood; diabetes involves deficiency or resistance, not absence as a sign.
• D: Insulin does not appear in urine under normal or diabetic conditions.

Final answer: B