What is the recommended management of hyperosmolar hyperglycemic state (HHS) in an adult patient?

Management of Hyperosmolar Hyperglycemic State (HHS)

Immediately admit the patient to an intensive care unit and begin aggressive fluid resuscitation with 0.9% sodium chloride, withholding insulin until blood glucose stops falling with fluids alone (unless ketonemia is present), while targeting an osmolality reduction of 3-8 mOsm/kg/h to prevent cerebral edema and central pontine myelinolysis. 1

Initial Assessment and Diagnosis

Confirm the diagnosis by verifying all five metabolic criteria are met simultaneously:

• Plasma glucose ≥600 mg/dL 2
• Effective serum osmolality ≥320 mOsm/kg, calculated as: 2[measured Na (mEq/L)] + glucose (mg/dL)/18 3, 2
• Arterial pH ≥7.30 (distinguishes from DKA) 2
• Serum bicarbonate ≥15 mEq/L 2
• Small or absent ketones in urine and serum (ketonemia ≤3.0 mmol/L) 2, 1

Obtain these laboratory tests immediately upon suspicion:

• Plasma glucose, serum electrolytes with calculated anion gap, and serum osmolality 3
• Blood urea nitrogen, creatinine, arterial blood gases 3
• Complete blood count with differential 3
• Urinalysis with urine ketones by dipstick 3
• Electrocardiogram and HbA1c 3
• Bacterial cultures (blood, urine, throat) if infection suspected 3
• Chest X-ray if pneumonia suspected 3

Calculate corrected sodium by adding 1.6 mEq/L to measured sodium for each 100 mg/dL glucose elevation above 100 mg/dL to assess true sodium status, as hyperglycemia causes pseudohyponatremia. 2

Fluid Resuscitation (First Priority)

Begin with 0.9% sodium chloride immediately to restore circulating volume and ensure vital organ perfusion. 1 The total body water deficit in HHS averages 9 liters (100-220 mL/kg). 3

Fluid administration protocol:

• Infuse 0.9% NaCl rapidly until vital signs stabilize and urine output reaches ≥0.5 mL/kg/h 1
• Aim to correct estimated fluid deficits within 24 hours 3
• Critical safety parameter: limit osmolality reduction to 3-8 mOsm/kg/h to prevent cerebral edema (70% mortality once clinical symptoms develop) and central pontine myelinolysis 3, 1
• Exercise caution in elderly patients to avoid fluid overload and noncardiogenic pulmonary edema 3

Insulin Therapy (Delayed Until Appropriate)

Withhold insulin until blood glucose stops falling with IV fluids alone, unless ketonemia is present. 3, 1 This is a critical distinction from DKA management—fluid replacement alone will cause glucose to fall, and premature insulin may be detrimental. 4

When to start insulin:

• Once glucose plateaus despite ongoing fluid resuscitation 1
• OR immediately if ketonemia is present (≥3.0 mmol/L) 1

Insulin dosing protocol:

• IV bolus of regular insulin 0.1-0.15 units/kg body weight 3
• Followed by continuous infusion at 0.1 unit/kg/h (5-7 units/h in adults) 3
• Target glucose reduction of 50-75 mg/dL/h 3
• If glucose does not fall by 50 mg/dL in the first hour, reassess hydration status; if adequate, double insulin infusion hourly until steady decline achieved 3

When glucose reaches 250-300 mg/dL:

• Add 5% or 10% dextrose to 0.45% saline solution 3
• Reduce insulin infusion to 0.05-0.1 units/kg/h 3
• Maintain glucose at 250-300 mg/dL for the first 24 hours (not the lower 150-200 mg/dL target used in DKA) to limit osmolality decline and prevent neurological complications 3

Potassium Management

Total body potassium deficit in HHS is 5-15 mEq/kg and requires aggressive replacement. 3

Potassium replacement protocol:

• If serum potassium <3.3 mEq/L: hold insulin and give potassium replacement until potassium ≥3.3 mEq/L to prevent life-threatening hypokalemia 3
• Once renal function is assured and potassium is known, add 20-30 mEq/L to IV fluids (2/3 KCl and 1/3 KPO₄) 3
• Insulin drives potassium intracellularly, precipitating dangerous hypokalemia if not anticipated 3

Phosphate considerations:

• Add 20-30 mEq/L potassium phosphate if serum phosphate <1.0 mg/dL or in patients with cardiac dysfunction, anemia, or respiratory depression 3
• Avoid overzealous phosphate therapy, which can cause severe hypocalcemia 3

Monitoring During Treatment

Draw blood every 2-4 hours to measure:

• Serum electrolytes, glucose, urea, creatinine 3
• Calculated effective osmolality 3
• Venous pH (to monitor for ketoacidosis development) 3

Recalculate corrected sodium with each glucose measurement to track true sodium status. 2

Identifying and Treating Precipitating Factors

Infection is the most common precipitant (must be identified and treated simultaneously with metabolic correction). 3 Other triggers include:

• Acute cerebrovascular accident or myocardial infarction 3
• Medications: corticosteroids, thiazide diuretics, SGLT2 inhibitors, sympathomimetics 3
• Non-compliance with diabetes therapy or undiagnosed diabetes 1

Hypothermia, if present, is a poor prognostic sign despite infection being common. 2

Resolution Criteria

HHS is resolved when all of the following are achieved:

• Osmolality <300 mOsm/kg 1
• Hypovolemia corrected (urine output ≥0.5 mL/kg/h) 1
• Cognitive status returned to pre-morbid state 1
• Blood glucose <15 mmol/L (270 mg/dL) 1

Critical Pitfalls to Avoid

Do not start insulin before fluids have stabilized glucose decline—this is the most common error and can worsen outcomes. 4, 1

Do not add dextrose too early (before glucose reaches 250-300 mg/dL), as this delays correction of hyperosmolarity and prolongs altered mental status. 3

Do not reduce osmolality faster than 3-8 mOsm/kg/h—rapid correction causes cerebral edema and central pontine myelinolysis with devastating neurological consequences. 3, 1

Do not use bicarbonate—pH is typically ≥7.30 in HHS, and no prospective studies support bicarbonate use. 3

Do not overlook potassium replacement—insulin therapy without adequate potassium monitoring and replacement can precipitate fatal arrhythmias. 3

Do not discontinue IV insulin without adequate subcutaneous insulin overlap—this causes rebound hyperglycemia. 3

Involve the diabetes specialist team as soon as possible and nurse patients in areas where staff are experienced in HHS management, given the 15% mortality rate. 4, 1