The patient presents with a depressed mental status (responsive to pain only). … Anion gap is 9. This patient has

• A. HHNK
• B. DKA
• C. Diabetes insipidus
• D. Pheochromocytoma

Answer: (A)

When a patient with diabetes presents with depressed mental status and the anion gap is normal, it points away from ketoacidosis and toward a hyperosmolar hyperglycemic state. The anion gap of 9 sits in the normal range, which means there isn’t the ketoacid buildup that drives metabolic acidosis in diabetic ketoacidosis. In a hyperosmolar hyperglycemic state (HHNK/HHS), there is profound dehydration from osmotic diuresis and very high blood glucose, leading to altered consciousness even without significant ketone production. That contrast—severe hyperglycemia with normal anion gap and mental status change—fits HHNK best. The other options don’t align with this pattern: diabetic ketoacidosis would involve an elevated anion gap from ketosis and acidosis; diabetes insipidus causes polyuria and hypernatremia without the same hyperglycemia/ketosis picture; pheochromocytoma presents differently, with hypertension and adrenergic symptoms rather than the hyperosmolar, ketone-free state.