What is the recommended dosage calculation for long-acting (BID) insulin?

Calculating the Dose for Long-Acting Insulin BID

For long-acting insulin administered twice daily (BID), start with 0.1-0.2 units/kg/day total, split evenly between morning and evening doses. 1

Initial Dosing Algorithm

• Calculate total daily insulin dose based on patient weight:

  • For insulin-naive patients: 0.1-0.2 units/kg/day 1
  • For patients already on insulin: Use current total daily dose, but consider 20% reduction if transitioning from another regimen to prevent hypoglycemia 1

• Divide the total daily dose equally between morning and evening doses 1

  • Example: For a 70kg insulin-naive patient, total daily dose would be 7-14 units, giving 3.5-7 units in the morning and 3.5-7 units in the evening 1

Titration Process

• Set a fasting plasma glucose (FPG) goal based on individual patient factors 1
• Adjust dose by 2 units every 3 days until FPG goal is reached without hypoglycemia 1
• If hypoglycemia occurs, determine the cause; if no clear reason is identified, reduce the dose by 10-20% 1

Special Considerations

• For elderly patients or those with renal impairment: Start with lower doses (0.1 units/kg/day) to minimize hypoglycemia risk 1, 2
• For patients on glucocorticoids (e.g., prednisone): Consider administering NPH insulin in the morning to counteract steroid-induced daytime hyperglycemia 1, 3
• For patients with higher insulin requirements (≥0.6 units/kg/day): Consider splitting the total daily dose with approximately 50-60% as basal insulin and 40-50% as prandial insulin 1

Monitoring and Assessment

• Assess adequacy of insulin dose at every visit 1
• Monitor for clinical signs of overbasalization: elevated bedtime-to-morning glucose differential, hypoglycemia, or high glucose variability 1
• For patients with type 1 diabetes, total daily insulin requirements typically range from 0.4 to 1.0 units/kg/day, with approximately 50% as basal insulin 1

Advantages of BID Dosing

• Twice-daily dosing of long-acting insulin can reduce predose hyperglycemia rates compared to once-daily dosing without increasing hypoglycemia risk 4
• For NPH insulin specifically, twice-daily dosing is often preferred due to its intermediate duration of action 1

Common Pitfalls to Avoid

• Avoid using sliding scale insulin alone, especially in type 1 diabetes patients 1
• Do not use premixed insulin therapy (e.g., 70/30) in hospital settings due to high risk of hypoglycemia 1
• When transitioning from IV to subcutaneous insulin, ensure overlap to prevent rebound hyperglycemia 1
• Remember that insulin requirements may increase during puberty, menses, and medical illness 1