What is the best course of treatment for a patient with severe hyperglycemia and a normal arterial blood gas (ABG) pH, likely indicating diabetes mellitus?

Management of Severe Hyperglycemia with Normal pH

This patient has Hyperosmolar Hyperglycemic State (HHS), not diabetic ketoacidosis, and requires immediate aggressive fluid resuscitation with isotonic saline followed by insulin therapy, with careful monitoring to prevent complications. 1

Diagnostic Confirmation

The presentation of glucose 716 mg/dL with arterial pH 7.4 definitively indicates HHS rather than DKA. 1, 2

• HHS diagnostic criteria: Blood glucose >600 mg/dL, effective serum osmolality >320 mOsm/kg H₂O, arterial pH >7.3, bicarbonate >15 mEq/L, and minimal or absent ketones 1
• DKA would require: pH <7.3, bicarbonate <15 mEq/L, and moderate to large ketones—none of which are present here 1, 2
• The normal pH essentially rules out DKA as the cause of this severe hyperglycemia 2

Immediate laboratory assessment needed:

• Complete metabolic panel including sodium (calculate corrected sodium), potassium, bicarbonate, BUN, creatinine 1
• Effective serum osmolality: 2[measured Na (mEq/L)] + glucose (mg/dL)/18 1, 3
• Urinalysis and blood/urine ketones to confirm absence of significant ketosis 1
• Arterial blood gas if not already obtained 1

Immediate Management Protocol

Fluid Resuscitation (First Priority)

Begin isotonic saline (0.9% NaCl) at 15-20 mL/kg/h (typically 1-1.5 L in the first hour) for intravascular volume expansion and restoration of renal perfusion. 1

• This aggressive fluid replacement is critical—patients with HHS require an average of 9 L over 48 hours 4
• After initial resuscitation and once corrected sodium is assessed, fluid choice may be adjusted based on sodium levels 1, 3
• If corrected sodium remains elevated after initial resuscitation, switch to 0.45% NaCl at 4-14 mL/kg/h based on hemodynamic status 3

Insulin Therapy (Second Priority)

Do NOT start insulin until potassium is confirmed to be ≥3.3 mEq/L, as insulin will drive potassium intracellularly and can precipitate life-threatening hypokalemia. 1

Once potassium is adequate:

• Initial bolus: 0.15 units/kg IV regular insulin 1
• Continuous infusion: 0.1 unit/kg/h (typically 5-10 units/hour) 1, 3
• Target glucose decline: 50-75 mg/dL per hour 1, 3
• When glucose reaches 250-300 mg/dL, decrease insulin to 0.05-0.1 U/kg/h and add 5-10% dextrose to IV fluids 3
• Maintain glucose at 250-300 mg/dL until hyperosmolarity resolves 3

Critical pitfall: Continuous intravenous insulin infusion is the preferred regimen for hyperglycemic crises, not subcutaneous sliding scale insulin 5

Potassium Management (Essential)

Potassium replacement is critical to prevent life-threatening hypokalemia, which occurs in approximately 50% of patients during treatment and is associated with increased mortality. 5

• If K+ <3.3 mEq/L: Hold insulin and give potassium 20-40 mEq/h until K+ ≥3.3 mEq/L 1
• If K+ 3.3-5.3 mEq/L: Add 20-30 mEq/L to IV fluids (2/3 KCl and 1/3 KPO4) 1, 3
• If K+ >5.3 mEq/L: Do not give potassium but check levels every 2 hours 1

Monitoring Protocol

Check every 2-4 hours: 1, 3

• Serum glucose (bedside and laboratory)
• Electrolytes (sodium—both measured and corrected, potassium, chloride, bicarbonate)
• BUN, creatinine
• Effective serum osmolality
• Venous pH if acidosis develops

Critical correction rate targets to avoid complications: 1, 3

• Osmolality decrease: Not exceeding 3 mOsm/kg/H₂O per hour
• Sodium correction: Not exceeding 10-12 mEq/L in first 24 hours or 18 mEq/L in first 48 hours (to prevent osmotic demyelination syndrome)
• Glucose decline: 50-75 mg/dL per hour

Identify and Treat Precipitating Cause

Underlying infections are the most common precipitating cause of HHS and must be identified and treated. 5, 4

Other common precipitants to evaluate:

• Medications (corticosteroids, thiazides, atypical antipsychotics) 4
• Myocardial infarction or stroke 5
• Non-compliance with diabetes medications 4
• Undiagnosed or undertreated diabetes 4

Special Considerations

If the patient is elderly or has cardiac/renal compromise: 1

• Use more cautious fluid rates with closer monitoring
• Frequent assessment of cardiac, renal, and mental status during fluid resuscitation to avoid iatrogenic fluid overload
• Elderly patients are at particularly high risk for complications and have impaired thirst mechanisms contributing to severe dehydration 1

Transition to subcutaneous insulin: 5

• Only after patient is stable with normal anion gap, resolution of hyperosmolarity, hemodynamically stable, and has stable nutrition plan
• Estimate daily subcutaneous insulin requirement from average insulin infused during 12 hours before transition
• Overlap IV and subcutaneous insulin by 1-2 hours to prevent rebound hyperglycemia 5

Critical Pitfalls to Avoid

• Never use sliding scale insulin alone for inpatient hyperglycemia management—this is strongly discouraged 5
• Do not correct glucose too rapidly—this can worsen hyperosmolarity and cause cerebral edema 1, 3
• Do not start insulin before confirming adequate potassium—severe hypokalemia (<2.5 mEq/L) is associated with increased mortality 5
• Do not overlook corrected sodium calculation—measured sodium will be falsely low due to hyperglycemia (add 1.6 mEq/L for each 100 mg/dL glucose above 100 mg/dL) 3
• Monitor for vascular complications: Mesenteric artery occlusion, myocardial infarction, disseminated intravascular coagulation, and rhabdomyolysis can occur with HHS 4