A 62-year-old woman with type 2 diabetes mellitus presents with a 5-day history of progressive confusion, polyuria, and polydipsia. She had been taking her medications regularly. On examination, she is lethargic, blood pressure is 95/60 mmHg, heart rate 110/min, and skin turgor is poor. Laboratory findings: glucose 1100 mg/dL, osmolality 340 mOsm/kg, pH 7.32, HCO₃⁻ 18 mEq/L, anion gap 12, serum Na⁺ 125 mEq/L (corrected Na⁺ 135 mEq/L), and creatinine 2.8 mg/dL. Urine ketones are negative. What is the most appropriate immediate next step in management?

Explanation

## HHS vs. DKA: Differential Diagnosis and Management ### Clinical Recognition of HHS **Key Point:** This patient has Hyperosmolar Hyperglycemic State (HHS), NOT DKA, based on: - Minimal ketosis (negative urine ketones) - Normal anion gap (12) - Preserved pH (7.32, mild acidosis only) - Extreme hyperglycemia (1100 mg/dL) - Very high osmolality (340 mOsm/kg) - Severe dehydration (poor turgor, hypotension) ### HHS vs. DKA Comparison | Feature | DKA | HHS | |---|---|---| | **Glucose** | 250–600 mg/dL | 600–2000 mg/dL | | **pH** | < 7.30 | > 7.30 | | **HCO₃⁻** | < 15 mEq/L | > 18 mEq/L | | **Anion Gap** | > 12 | Normal | | **Ketones** | Large | Absent/small | | **Osmolality** | 300–320 mOsm/kg | > 320 mOsm/kg | | **Dehydration** | Moderate | Severe | | **Mortality** | 1–5% | 5–15% | **High-Yield:** HHS is more common in elderly type 2 diabetics and carries higher mortality due to severe dehydration and thrombotic complications. ### Immediate Management Algorithm for HHS ```mermaid flowchart TD A[HHS Diagnosis]:::outcome --> B[Assess Severity]:::decision B -->|Mild-Moderate| C[0.45% or 0.9% NS<br/>500 mL/hr]:::action B -->|Severe/Shock| D[0.9% NS Bolus<br/>1-2 L rapid]:::urgent D --> E[Reassess Vitals<br/>& Urine Output]:::action C --> F[Monitor Osmolality<br/>& Glucose q1-2h]:::action E --> F F --> G{Osmolality<br/>decreasing?}:::decision G -->|Yes| H[Continue fluids<br/>Slower rate when<br/>osmolality < 320]:::action G -->|No| I[Increase infusion rate<br/>or change to 0.9% NS]:::action H --> J[Start Insulin<br/>0.05 units/kg/hr<br/>when glucose drops<br/>to 250-300]:::action I --> J ``` ### Why Fluid Resuscitation is PARAMOUNT in HHS **Clinical Pearl:** Unlike DKA, insulin is NOT the first-line therapy in HHS. Fluid resuscitation alone can lower glucose by 200–300 mg/dL through: 1. Dilution of hyperglycemia 2. Restoration of glomerular filtration 3. Reduction of counterregulatory hormones **Warning:** Insulin in HHS can cause: - Rapid osmolality drop → cerebral edema - Hypokalemia (more severe than DKA) - Hypoglycemia (glucose drops faster than in DKA) Insulin is started ONLY after: - Initial fluid resuscitation - Glucose has fallen to 250–300 mg/dL - K⁺ is being monitored ### Hyponatremia Correction **Key Point:** Corrected Na⁺ = 135 mEq/L (normal). The low measured Na⁺ (125) is pseudohyponatremia due to hyperglycemia (osmotic shift of water into intracellular space). As glucose normalizes, Na⁺ will rise naturally. Do NOT add hypertonic saline. ### Thrombotic Complications **High-Yield:** HHS carries risk of: - Thromboembolism (DVT, PE, stroke) - Acute coronary syndrome - Mesenteric ischemia Consider VTE prophylaxis (mechanical ± pharmacologic) unless contraindicated. [cite:Harrison 21e Ch 396]