Management of Hyperosmolar Hyperglycemic State (HHS)
Begin immediate fluid resuscitation with 0.9% sodium chloride at 15-20 mL/kg/hour during the first hour, and withhold insulin until blood glucose stops falling with IV fluids alone unless ketonemia is present. 1, 2, 3
Initial Assessment and Diagnostic Confirmation
Confirm HHS diagnosis with blood glucose ≥600 mg/dL, arterial pH >7.3, serum bicarbonate >15 mEq/L, and effective serum osmolality ≥320 mOsm/kg H₂O calculated as: 2[measured Na⁺] + glucose (mg/dL)/18. 4, 1
Obtain immediately: arterial blood gases, complete blood count with differential, urinalysis, plasma glucose, blood urea nitrogen, electrolytes, chemistry profile, creatinine, and electrocardiogram. 4, 1 Order chest X-ray and cultures to identify precipitating infections, which are the most common trigger. 5, 1
Correct measured sodium for hyperglycemia by adding 1.6 mEq/L for each 100 mg/dL glucose elevation above 100 mg/dL to assess true sodium status. 4, 1
Fluid Resuscitation Protocol
Phase 1: First Hour (0-60 minutes)
Administer 0.9% sodium chloride at 15-20 mL/kg/hour (1-1.5 L in average adult) to restore circulatory volume and tissue perfusion. 4, 5, 1 The total body water deficit in HHS averages 9 liters (100-200 mL/kg). 5, 1
Phase 2: Hours 1-24
After initial resuscitation, adjust fluid choice based on corrected sodium: if corrected sodium is normal or elevated, switch to 0.45% NaCl at 4-14 mL/kg/hour; if corrected sodium is low, continue 0.9% NaCl at similar rate. 1, 3 Aim to replace estimated fluid deficits within 24 hours. 1
Critical monitoring point: In elderly patients or those with renal/cardiac compromise, perform frequent cardiac, renal, and mental status assessments to avoid iatrogenic fluid overload. 1, 3
Insulin Therapy
Delay insulin administration until blood glucose stops falling with IV fluids alone, unless ketonemia is present. 1, 2, 3 This differs fundamentally from DKA management—early insulin use before adequate fluid resuscitation may be detrimental. 2
Once indicated, administer IV bolus of regular insulin at 0.15 units/kg body weight, followed by continuous infusion at 0.1 unit/kg/hour (5-7 units/hour in adults). 4, 5, 1 If plasma glucose does not fall by 50 mg/dL in the first hour and hydration is acceptable, double the insulin infusion hourly until achieving steady glucose decline of 50-75 mg/hour. 4
When plasma glucose reaches 300 mg/dL, decrease insulin infusion to 0.05-0.1 units/kg/hour (3-6 units/hour) and add 5-10% dextrose to IV fluids. 4, 5, 1 Target blood glucose of 10-15 mmol/L (180-270 mg/dL) in the first 24 hours. 3
Electrolyte Management
Potassium Replacement
Once renal function is confirmed and serum potassium is known, add 20-40 mEq/L potassium to IV fluids (2/3 KCl and 1/3 KPO₄). 4, 1 Begin potassium replacement when levels fall below 5.5 mEq/L, as insulin therapy will drive potassium intracellularly. 5, 1 Total body potassium deficit in HHS is 5-15 mEq/kg. 1
Critical safety point: Exclude hypokalemia (K⁺ <3.3 mEq/L) before starting insulin therapy. 4
Monitor serum potassium every 2-4 hours during treatment. 5, 1
Monitoring During Treatment
Check blood glucose every 1-2 hours until stable. 1 Draw blood every 2-4 hours for serum electrolytes, glucose, blood urea nitrogen, creatinine, osmolality, and venous pH. 4, 5, 1
Target osmolality reduction of 3-8 mOsm/kg/hour to prevent cerebral edema and osmotic demyelination syndrome. 5, 1, 2, 3 Rapid osmolality changes may precipitate central pontine myelinolysis. 2
Monitor fluid input/output, vital signs, and mental status frequently. 1 An initial rise in sodium is expected and does not itself indicate need for hypotonic fluids. 2
Transition to Subcutaneous Insulin
Administer basal insulin 2-4 hours before discontinuing IV insulin to prevent rebound hyperglycemia and recurrence of metabolic decompensation. 4, 1, 6 This timing is critical—premature termination of IV insulin is a common management pitfall. 6
Treatment of Precipitating Causes
Identify and treat underlying causes simultaneously with metabolic correction, particularly infections (most common precipitant), myocardial infarction, stroke, and sepsis. 4, 5, 1, 7 Appropriate management of precipitating illnesses reduces the high mortality associated with HHS. 1, 7
Resolution Criteria
HHS is resolved when: osmolality <300 mOsm/kg, hypovolemia corrected (urine output ≥0.5 mL/kg/hour), cognitive status returned to baseline, and blood glucose <15 mmol/L (270 mg/dL). 3
Special Considerations
Bicarbonate administration is generally not recommended. 4, 1
Involve the diabetes specialist team as soon as possible and nurse patients in areas where staff are experienced in HHS management. 2, 3
Many patients presenting with HHS will not require long-term insulin therapy after recovery and can be managed with diet or oral agents. 7