A 68-year-old woman is brought to the emergency department at 2 AM by her daughter, who reports that her mother has been 'acting strange' for the past 6 hours. The patient is picking at invisible objects in the air, is extremely agitated, and keeps asking 'Where am I? What time is it?' repeatedly. She is diaphoretic and her heart rate is 118/min. The daughter states that her mother has been living independently, managing her finances, and driving until yesterday. On examination, the patient is disoriented to time and place but knows her name. She cannot perform serial 7s. Vital signs: BP 160/95 mmHg, HR 118/min, RR 24/min, Temperature 37.2°C. Capillary blood glucose is 480 mg/dL. What is the most likely diagnosis?

Explanation

## Clinical Diagnosis: Hyperglycemic Hyperosmolar State (HHS) with Secondary Delirium ### Acute Delirium in a Metabolically Deranged Patient **Key Point:** Acute onset of disorientation, agitation, hallucinations (picking at invisible objects), and autonomic instability in a previously cognitively intact patient indicates **delirium** with an identifiable metabolic cause. ### Delirium vs. Dementia: Critical Distinctions | Feature | Delirium | Dementia | |---------|----------|----------| | **Onset** | Acute (hours–days) | Insidious (months–years) | | **Prior cognitive status** | Previously normal or stable | Gradual decline over time | | **Attention/Consciousness** | Severely impaired; altered level of consciousness | Relatively preserved until late stages | | **Fluctuation** | Marked, often worse at night (sundowning) | Stable, progressive | | **Reversibility** | Often reversible if cause identified and treated | Usually irreversible | | **Vital signs** | Often abnormal (fever, tachycardia, hypertension) | Usually normal | | **Hallucinations** | Visual, tactile (picking, seeing bugs) | Less common early | ### Why This Is Delirium, Not Dementia 1. **Acute onset:** 6 hours of confusion in a woman who was independent and driving yesterday 2. **Fluctuating course:** Agitation, disorientation, visual hallucinations (picking at invisible objects) 3. **Autonomic instability:** Tachycardia (118), hypertension (160/95), diaphoresis, tachypnea (24) 4. **Metabolic derangement:** Capillary glucose 480 mg/dL (severe hyperglycemia) 5. **Temporal relationship:** Acute metabolic derangement → acute mental status change **High-Yield:** Hyperglycemia (especially >400 mg/dL) causes hyperosmolarity, which impairs cerebral function and precipitates delirium. This is a medical emergency. ### Pathophysiology of Delirium in HHS ```mermaid flowchart TD A[Uncontrolled hyperglycemia]:::outcome --> B[Osmotic diuresis]:::action B --> C[Severe dehydration + electrolyte loss]:::outcome C --> D[Hyperosmolarity]:::outcome D --> E[Cerebral edema / altered cerebral perfusion]:::action E --> F[Delirium: disorientation, hallucinations, agitation]:::urgent A --> G[Metabolic acidosis / ketosis]:::outcome G --> E H[Autonomic activation]:::action --> I[Tachycardia, hypertension, diaphoresis]:::outcome ``` **Clinical Pearl:** The **nocturnal onset** (2 AM) with acute worsening is typical of delirium, especially in metabolic emergencies. Dementia does not present acutely overnight in a previously well person. ### Management 1. **Immediate:** IV fluids (normal saline), insulin infusion, electrolyte monitoring 2. **Supportive:** Reorientation, safe environment, treat underlying precipitant 3. **Prognosis:** Mental status typically improves dramatically as glucose and osmolarity normalize **Mnemonic: DELIRIUM causes** — **M**etabolic (hyperglycemia, electrolytes), **I**nfection, **D**rugs, **A**cute CNS, **H**ypoxia, **E**ndocrine, **T**emperature, **I**ntoxication, **O**rgan failure, **N**utrition