What is the management of a patient with hyperglycemia (elevated blood glucose level)?

Management of Blood Glucose >300 mg/dL

For a patient with blood glucose >300 mg/dL, initiate a basal-bolus subcutaneous insulin regimen with a total daily dose of 0.3-0.5 units/kg: give 50% as basal insulin (glargine or detemir) once daily and 50% as rapid-acting insulin (lispro, aspart, or glulisine) divided before meals, with additional correction doses for persistent hyperglycemia. 1

Initial Assessment

Before initiating treatment, you must determine the severity and identify any life-threatening complications:

• Check for diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS) by assessing mental status changes, severe dehydration, fruity breath odor, abdominal pain, nausea/vomiting 1
• Obtain laboratory tests: complete metabolic panel, serum ketones (or urine ketones), arterial blood gas if DKA suspected, and urinalysis 1
• Calculate effective serum osmolality: 2[measured Na (mEq/L)] + glucose (mg/dL)/18 2
  • If osmolality ≥320 mOsm/kg with glucose ≥600 mg/dL and minimal ketones, this indicates HHS requiring ICU-level care 3
  • If significant ketonemia (>3.0 mmol/L) or acidosis (pH <7.3), this indicates DKA requiring IV insulin 3
• Assess hydration status and identify precipitating causes such as infection, missed insulin doses, or new medications 2, 1

Treatment Algorithm Based on Clinical Scenario

For Stable Outpatients or Non-Critical Inpatients (No DKA/HHS)

Subcutaneous insulin is the preferred approach for patients without hyperglycemic crisis 2, 1:

Step 1: Calculate Total Daily Dose (TDD)

• Use 0.3-0.5 units/kg body weight 1
• For example, a 70 kg patient: 70 × 0.4 = 28 units total daily

Step 2: Distribute Insulin Doses

• 50% as basal insulin (long-acting): Give glargine or detemir once daily 1
  • Using the example above: 14 units once daily
• 50% as prandial insulin (rapid-acting): Divide into three pre-meal doses 1
  • Using the example above: ~5 units before each meal (breakfast, lunch, dinner)

Step 3: Add Correction Doses

• Use rapid-acting insulin for blood glucose persistently >180 mg/dL 1
• A typical correction factor: 1 unit lowers glucose by ~50 mg/dL (adjust based on individual sensitivity) 4

Step 4: Ensure Adequate Hydration

• Encourage oral fluid intake to prevent dehydration 5
• Consider IV fluids if oral intake is inadequate 5

Step 5: Monitor Closely

• Check blood glucose every 4-6 hours initially until stable 5
• Monitor before meals and at bedtime once stabilized 1
• Adjust insulin doses daily based on glucose patterns 1

For Critical Patients or Hyperglycemic Crisis (DKA/HHS)

Continuous IV insulin infusion is mandatory for patients with severe hyperglycemia complicated by DKA, HHS, or critical illness 2, 1:

Fluid Resuscitation (First Priority)

• Adults: Start with 0.9% NaCl at 15-20 mL/kg/h (or 1-1.5 L) in the first hour 2
  • Average fluid requirement: 9 L over 48 hours 6
  • Once glucose reaches 250 mg/dL, switch to 5% dextrose with 0.45-0.75% NaCl 2
• Pediatric patients (<20 years): 0.9% NaCl at 10-20 mL/kg in first hour (max 50 mL/kg over first 4 hours) 2
  • Continue at 1.5 times maintenance (5 mL/kg/h) with 0.45-0.9% NaCl 2
  • Critical: Decrease osmolality no faster than 3 mOsm/kg/h to prevent cerebral edema 2, 3

Potassium Replacement (Before Starting Insulin)

• Do not start insulin if K+ <3.3 mEq/L - replace potassium first 2
• Once urine output established and K+ >3.3 mEq/L, add 20-40 mEq/L to IV fluids 2
• Hypokalaemia occurs in ~50% during treatment and severe hypokalaemia (<2.5 mEq/L) increases mortality 2

IV Insulin Protocol

• Adults:
  • Give 0.15 units/kg IV bolus, then 0.1 units/kg/h continuous infusion 2
  • Alternative: 0.14 units/kg/h continuous infusion without bolus 6
  • Target glucose decline: 50-75 mg/dL per hour 2
• Pediatric patients:
  • No initial bolus - start continuous infusion at 0.1 units/kg/h 2
• If glucose doesn't fall by 50 mg/dL in first hour: Check hydration, then double insulin infusion rate hourly until steady decline achieved 2
• Target glucose range: 140-180 mg/dL for most critically ill patients 2, 1
• Monitor glucose every 30 minutes to 2 hours during IV insulin therapy 1

Transition to Subcutaneous Insulin

• When to transition: Patient stable, glucose consistently <200 mg/dL, normal anion gap (if DKA), hemodynamically stable, stable nutrition plan 2
• Calculate subcutaneous dose: Use average insulin infused over 12 hours before transition × 2 to get 24-hour total 2
  • Example: If receiving 1.5 units/h average → 36 units/24 hours total daily dose
• Give basal insulin 2-4 hours before stopping IV insulin to prevent rebound hyperglycemia 1
• Distribute as 50% basal and 50% prandial insulin 2, 1

Critical Pitfalls to Avoid

• Never use sliding scale insulin alone without basal insulin - this approach is ineffective and strongly discouraged 2, 1, 7
• Never stop insulin when glucose normalizes if ketones persist - continue insulin until ketones clear 5
• Never correct glucose too rapidly - aim for gradual decline to prevent cerebral edema, especially in children 2, 3
• Never start insulin before checking potassium - severe hypokalaemia can be fatal 2
• Never discontinue IV insulin without prior subcutaneous basal insulin - this causes rebound hyperglycemia 2, 1

Monitoring for Hypoglycemia

• Symptoms include: sweating, tremor, palpitations, hunger, confusion, slurred speech, or altered mental status 4
• Treatment: Give 15-20 g oral glucose (glucose tablets or sugar-containing foods) if patient conscious 2
• Severe hypoglycemia: Requires glucagon IM injection or IV glucose administration 2, 4
• Patients should always carry quick sugar source (hard candy or glucose tablets) 4

Long-Term Management After Acute Episode

• Add metformin as first-line oral therapy once acute hyperglycemia controlled, if not contraindicated 1, 5
• Consider continuing insulin long-term for patients with very high HbA1c (>10%) or severe hyperglycemia 1
• Provide diabetes self-management education to prevent recurrence 1
• Schedule follow-up within 1-2 weeks to reassess glycemic control 1
• Target HbA1c <7% for most adults with diabetes 5

Special Considerations

• Infection is the most common precipitant of hyperglycemic crises and must be identified and treated 6, 3
• Elderly patients with HHS require careful fluid management to avoid overload 2, 3
• Patients with cardiac or renal disease need frequent assessment during fluid resuscitation to prevent iatrogenic fluid overload 2