What is the recommended insulin coverage for severe hyperglycemia (elevated blood glucose)?

Management of Severe Hyperglycemia (Blood Glucose >400 mg/dL)

For blood glucose levels exceeding 400 mg/dL, intravenous insulin therapy should be initiated immediately, with an initial dose of 0.1 units/kg/hour, adjusted every 1-2 hours to achieve a target glucose range of 140-180 mg/dL. 1

Initial Assessment and Monitoring

• Assess for:

  • Signs of dehydration
  • Electrolyte abnormalities (particularly potassium)
  • Acidosis
  • Mental status changes
  • Precipitating factors (infection, medication non-adherence, new medications)

• Monitoring requirements:

  • Blood glucose every 1-2 hours until stable
  • Electrolytes every 2-4 hours initially
  • Fluid status and vital signs hourly

Treatment Algorithm for Blood Glucose >400 mg/dL

For Critically Ill Patients (ICU Setting):

1. Start IV insulin infusion immediately:

   • Initial dose: 0.1 units/kg/hour 2
   • Adjust dose every 1-2 hours based on glucose response
   • Target glucose range: 140-180 mg/dL 1

2. IV Fluid Management:

   • Isotonic fluids (normal saline) at 15-20 mL/kg in first hour
   • Subsequent rate based on hemodynamic status and fluid deficit
   • Add dextrose when glucose falls below 250 mg/dL to prevent hypoglycemia

3. Electrolyte Replacement:

   • Monitor potassium, magnesium, and phosphate
   • Replace as needed to maintain normal levels
   • Anticipate potassium shifts with insulin therapy

For Non-Critically Ill Patients:

1. Initial Management:

   • If patient has altered mental status, significant dehydration, or acidosis: transfer to ICU for IV insulin therapy
   • If stable: consider subcutaneous insulin regimen

2. Subcutaneous Insulin Regimen (if appropriate):

   • Give correction dose: 0.1 units/kg of rapid-acting insulin
   • Initiate basal-bolus insulin regimen (not sliding scale alone) 1, 3
   • Calculate total daily dose: 0.5-0.8 units/kg/day
   • Distribute as 50% basal and 50% bolus insulin

3. Monitoring and Follow-up:

   • Check blood glucose every 2-4 hours
   • Reassess insulin doses based on response
   • Target glucose range: 140-180 mg/dL 1

Special Considerations

For Patients with Type 1 Diabetes:

• Always assess for ketoacidosis
• Never discontinue insulin completely
• Consider insulin pump failure or site issues if using continuous subcutaneous insulin infusion 4

For Patients with Type 2 Diabetes:

• For youth with marked hyperglycemia (≥250 mg/dL), initiate basal insulin while starting metformin 1
• In adults with severe hyperglycemia (≥300 mg/dL), insulin is the preferred initial therapy 1

Transition from IV to Subcutaneous Insulin

1. Calculate 24-hour insulin requirement from IV infusion rate
2. Convert to subcutaneous regimen:
   • 50% as basal insulin (glargine, detemir, or degludec)
   • 50% as prandial insulin divided between meals
3. Administer first dose of basal insulin 2-4 hours before discontinuing IV insulin
4. Continue frequent monitoring during transition

Common Pitfalls to Avoid

• Do not rely solely on sliding scale insulin for persistent hyperglycemia
• Do not discontinue IV insulin abruptly without overlapping subcutaneous insulin
• Do not underestimate fluid requirements in severely hyperglycemic patients
• Do not fail to investigate the underlying cause of severe hyperglycemia
• Avoid overly aggressive glucose correction, which may lead to hypoglycemia 5
• Do not delay insulin therapy when blood glucose exceeds 400 mg/dL

By following this structured approach to managing severe hyperglycemia, you can effectively reduce blood glucose levels while minimizing the risk of complications such as hypoglycemia, electrolyte abnormalities, and fluid imbalances.