Medical Emergencies · patient case question
Over approximately what period does hemoglobin A1c reflect average blood glucose?
Patient case: Dry Mouth in a Cancer Survivor with Diabetes
Patient: 55-year-old male
Chief Complaint: “My mouth is always dry and food sticks to everything.”
Background: Type 2 diabetes mellitus, most recent HbA1c 8.4%. Prostate adenocarcinoma treated with external beam radiation directed to the pelvis 2 years ago, currently in remission with no evidence of recurrence. History of peptic ulcer disease. No radiation to the head or neck.
Medications: Metformin · Glipizide · Amitriptyline for diabetic neuropathy · Omeprazole
Vital Signs: BP 138/86 mmHg · HR 80 bpm · RR 16 · T 98.4°F
Findings: Dry, sticky mucosa with minimal salivary pooling in the floor of the mouth. Mirror adheres to the buccal mucosa. Multiple new cervical and root surface carious lesions. Fissured, erythematous tongue.
Show answer and explanation
Correct answer: D. 3 months
- A. Incorrect. A two-week window is what fructosamine measures, reflecting glycated serum proteins with a much shorter turnover.
- B. Incorrect. Twelve months is far beyond the lifespan of any circulating cell used for glycemic monitoring.
- C. Incorrect. Six months exceeds red cell lifespan. No single glycemic marker covers that period.
- D. Correct. The measurement reflects the lifespan of the erythrocyte, roughly 120 days, so it captures average glycemia over the preceding 2 to 3 months. The most recent weeks are weighted somewhat more heavily than the earliest.
Note: Interpretation thresholds: below 5.7% is normal, 5.7 to 6.4% indicates prediabetes, 6.5% or above is diagnostic of diabetes, and below 7% is the general treatment target. His 8.4% represents poor control, and above 8% elective surgical procedures warrant caution and medical consultation.
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