How to manage a patient with severe hyperglycemia?

Management of Severe Hyperglycemia in the Emergency Department

This patient requires immediate insulin therapy with intravenous regular insulin infusion, as the glucose >500 mg/dL represents severe hyperglycemia requiring urgent intervention, even though the venous blood gas shows no acidosis (pH 7.42, HCO3 24.7 mmol/L). 1

Immediate Assessment and Classification

Critical distinction: Despite the severe hyperglycemia (>500 mg/dL), this patient does not have diabetic ketoacidosis given the normal pH (7.42) and bicarbonate (24.7 mmol/L). 1 However, you must:

• Check serum ketones immediately to rule out early ketoacidosis, as hyperglycemia >16.5 mmol/L (297 mg/dL) in any diabetic patient warrants ketone assessment 1
• Measure serum osmolality urgently to evaluate for hyperosmolar hyperglycemic state (HHS), which presents with glucose often >600 mg/dL, osmolality >320 mOsm/L, and minimal acidosis 1
• Assess for clinical signs of HHS: altered mental status, severe dehydration, absence of Kussmaul respirations 1

Initial Insulin Therapy

Start continuous intravenous insulin infusion immediately - this is the preferred regimen for severe hyperglycemia in the emergency setting, regardless of diabetes type. 1, 2

IV Insulin Protocol:

• Begin insulin infusion at 0.1 units/kg/hour (typical starting rate 5-10 units/hour for most adults) 1
• Target glucose reduction of 50-70 mg/dL per hour initially, then maintain glucose 140-180 mg/dL once approaching target 1
• Do NOT start insulin if serum potassium <3.3 mEq/L - correct hypokalemia first as insulin drives potassium intracellularly 1, 3

Concurrent Fluid Resuscitation

Aggressive IV fluid administration is critical and must begin immediately:

• Start with 0.9% normal saline at 15-20 mL/kg/hour (1-1.5 L) in the first hour for most patients 1
• Reassess volume status and adjust rate based on hemodynamic response, urine output, and comorbidities 1
• Switch to 0.45% saline once glucose approaches 250-300 mg/dL and add dextrose to IV fluids to prevent hypoglycemia while continuing insulin 1

Electrolyte Management

Potassium monitoring and replacement is mandatory:

• Check potassium every 2-4 hours during insulin infusion 1, 3
• If K+ 3.3-5.3 mEq/L: Add 20-30 mEq potassium to each liter of IV fluid 1
• **If K+ <3.3 mEq/L:** Hold insulin and give potassium replacement until >3.3 mEq/L 1
• Hypokalemia occurs in ~50% of patients during treatment and severe hypokalemia (<2.5 mEq/L) increases mortality 1, 3

Monitoring Requirements

Point-of-care glucose testing every 1-2 hours until stable, then every 2-4 hours 1, 4

Laboratory monitoring:

• Serum electrolytes (especially potassium) every 2-4 hours initially 1
• Venous or arterial blood gas if acidosis suspected 1
• Serum osmolality if HHS suspected 1

Transition to Subcutaneous Insulin

Once the patient is stable (glucose <200-250 mg/dL, able to eat, hemodynamically stable), transition to subcutaneous insulin:

• Calculate total daily insulin requirement from the average IV insulin rate over the preceding 12 hours (e.g., 1.5 units/hour × 24 = 36 units/day) 1
• Give 50% as basal insulin (long-acting) and 50% as prandial insulin divided among meals 1, 5
• Administer first subcutaneous basal insulin dose 2-4 hours before stopping IV insulin to prevent rebound hyperglycemia 1

For hospitalized patients requiring subcutaneous insulin:

• If insulin-naive or on low-dose insulin at home: Start 0.3-0.5 units/kg/day total daily dose 5
• If on high-dose home insulin (≥0.6 units/kg/day): Reduce home dose by 20% to prevent hypoglycemia 5

Common Pitfalls to Avoid

• Never use sliding scale insulin alone for severe hyperglycemia - it treats hyperglycemia after it occurs rather than preventing it 1, 4
• Do not delay insulin therapy while waiting for additional testing - severe hyperglycemia requires immediate treatment 1
• Avoid overly aggressive glucose lowering - target 140-180 mg/dL, not normoglycemia, to minimize hypoglycemia risk 1, 4
• Do not stop IV insulin abruptly without overlapping subcutaneous basal insulin 1
• Never ignore potassium levels - insulin-induced hypokalemia can cause fatal arrhythmias 1, 3

Determine Underlying Diabetes Type

Check HbA1c on admission to assess chronic glycemic control and guide discharge planning 1, 4

Consider type 1 diabetes if: young age, lean body habitus, positive islet autoantibodies, or history of ketoacidosis 1

Consider type 2 diabetes if: older age, obesity, family history, or gradual onset 1