How do you calculate the initial dose of long-acting insulin (e.g. glargine (insulin glargine) or detemir (insulin detemir)) for a patient with uncontrolled hyperglycemia on a sliding scale insulin regimen?

Calculating Long-Acting Insulin Needs for Patients on Sliding Scale with Uncontrolled Blood Sugar

For patients with uncontrolled hyperglycemia on sliding scale insulin, initiate long-acting insulin at 0.1-0.2 units/kg/day, with individualized titration based on fasting blood glucose levels. 1

Initial Dosing Calculation

• For insulin-naive patients, start basal insulin (glargine or detemir) at 0.1-0.2 units/kg of body weight per day 1
• For a typical adult, this often translates to approximately 10 units as a starting dose 1
• If the patient has severe hyperglycemia (blood glucose >300-350 mg/dL or HbA1c >10%), consider starting at the higher end of the range 1
• Administer long-acting insulin once daily, preferably at the same time each day 1

Specific Starting Doses Based on Clinical Setting

• For hospitalized patients on enteral/parenteral feeding with no prior basal insulin:

  • Consider 5 units NPH/detemir every 12 hours or 10 units glargine/degludec daily 1
  • Calculate from total daily dose (TDD) of sliding scale insulin if available 1

• For patients with uncontrolled hyperglycemia despite sliding scale:

  • If sliding scale requirements exceed 20 units per day, this can guide initial basal insulin dosing 1
  • Continue sliding scale insulin for correction while titrating basal insulin 1

Titration Algorithm

• After initiating basal insulin, adjust the dose every 2-3 days based on fasting blood glucose (FBG) levels 2:

  • If FBG ≥100-<120 mg/dL: Increase by 0-2 units
  • If FBG ≥120-<140 mg/dL: Increase by 2 units
  • If FBG ≥140-<180 mg/dL: Increase by 4 units
  • If FBG ≥180 mg/dL: Increase by 6-8 units
  • If any FBG <72 mg/dL (hypoglycemia): Reduce dose by 2-4 units 2

• Target fasting glucose range: 90-150 mg/dL 1

• If 50% of fasting glucose values are above target: Increase dose by 2 units 1

• If >2 fasting glucose values/week are <80 mg/dL: Decrease dose by 2 units 1

Clinical Considerations

• Insulin detemir may require higher total daily doses compared to glargine (approximately 20-30% higher) to achieve similar glycemic control 3
• Both glargine and detemir have similar duration of action (close to 24 hours) at clinically relevant doses of 0.35-0.8 U/kg 4
• Long-acting insulin analogs (glargine, detemir) have lower risk of nocturnal hypoglycemia compared to NPH insulin 5
• Consider patient's renal and hepatic function when dosing insulin, as impaired function may require dose adjustments 6

Transitioning from Sliding Scale to Basal-Bolus Regimen

• Basal-bolus insulin regimen (basal insulin plus mealtime insulin) provides better glycemic control than sliding scale alone 1
• When transitioning:
  1. Calculate total daily sliding scale insulin used over previous 24-48 hours
  2. Allocate approximately 50% of this amount to basal insulin 1
  3. Distribute the remaining 50% as prandial insulin before meals 1
  4. Continue correction insulin (sliding scale) as needed before meals 1

Special Considerations

• For older adults (≥65 years), consider starting at the lower end of the dosing range (0.1 units/kg) due to increased risk of hypoglycemia 1
• For perioperative patients, reduce evening/pre-procedure basal insulin dose by 25% to reduce hypoglycemia risk 1
• For patients with type 2 diabetes and obesity, consider weight-based dosing but be cautious of insulin resistance requiring higher doses 1

Monitoring and Adjustment

• Monitor blood glucose at least daily when initiating or changing insulin doses 1
• Evaluate for overbasalization (high bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, high glucose variability) 1
• If basal insulin has been optimized but blood glucose remains uncontrolled, consider adding prandial insulin or GLP-1 receptor agonist 1