How do you restart short-acting (e.g. aspart, glulisine, lispro) and long-acting (e.g. detemir, glargine, degludec) insulin therapy?

Restarting Short-Acting and Long-Acting Insulin Therapy

When restarting insulin therapy, begin with basal (long-acting) insulin alone at 0.1-0.2 units/kg/day administered in the morning, titrate based on fasting glucose goals of 90-150 mg/dL, and only add prandial (short-acting) insulin if postprandial hyperglycemia persists despite optimized basal insulin. 1

Initial Approach: Start with Basal Insulin Only

• Begin with basal insulin monotherapy using glargine (U-100 or U-300), detemir, degludec, or NPH insulin 1
• Start at 0.1-0.2 units/kg/day based on body weight and degree of hyperglycemia 1
• Administer in the morning rather than bedtime to simplify the regimen and reduce nocturnal hypoglycemia risk 1
• Long-acting analogs (glargine, detemir, degludec) reduce nocturnal and overall hypoglycemia risk compared to NPH insulin 1

Titration Strategy for Basal Insulin

• Titrate every 2-7 days based on fasting finger-stick glucose values 1
• Target fasting glucose: 90-150 mg/dL (5.0-8.3 mmol/L) 1
• If ≥50% of fasting values exceed goal: Increase dose by 2 units 1
• If >2 fasting values/week are <80 mg/dL (<4.4 mmol/L): Decrease dose by 2 units 1

Important Conversion Considerations

When switching between basal insulins, doses can typically be converted unit-for-unit with subsequent adjustment, but reduce initial dose by 10-20% when switching from detemir or U-300 glargine to other basal insulins in patients at high hypoglycemia risk 1

When to Add Prandial (Short-Acting) Insulin

Only advance to prandial insulin if:

• Basal insulin is optimized (acceptable fasting glucose) but A1C remains above target 1
• Significant postprandial hyperglycemia is documented 1
• Signs of overbasalization are present (bedtime-to-morning glucose differential ≥50 mg/dL, hypoglycemia, high glucose variability) 1

Starting Prandial Insulin

• Initial dose: 4 units OR 10% of basal insulin dose at the largest meal or meal with greatest postprandial excursion 1
• Use rapid-acting analogs (lispro, aspart, glulisine) administered just before meals 1
• Rapid-acting analogs provide better postprandial control and lower late postprandial hypoglycemia risk compared to regular human insulin 1, 2
• Do not use rapid- or short-acting insulin at bedtime 1

Titration of Prandial Insulin

• Monitor premeal glucose before lunch and dinner every 2 weeks 1
• Target premeal glucose: 90-150 mg/dL (5.0-8.3 mmol/L) 1
• If ≥50% of premeal values exceed goal over 2 weeks: Increase prandial dose or add another agent 1
• If >2 premeal values/week are <90 mg/dL: Decrease medication dose 1
• Consider decreasing basal insulin when significantly increasing evening prandial insulin doses 1

Alternative: Consider GLP-1 RA Before Prandial Insulin

Before adding prandial insulin, consider adding a GLP-1 receptor agonist or dual GIP/GLP-1 RA (tirzepatide, semaglutide) to basal insulin, as this approach reduces hypoglycemia risk and promotes weight loss compared to prandial insulin 1

Simplified Sliding Scale During Adjustment

While adjusting prandial insulin, use a simplified correction scale:

• Premeal glucose >250 mg/dL (>13.9 mmol/L): Give 2 units short- or rapid-acting insulin 1
• Premeal glucose >350 mg/dL (>19.4 mmol/L): Give 4 units short- or rapid-acting insulin 1
• Discontinue sliding scale when not needed daily 1

Critical Pitfalls to Avoid

• Avoid overbasalization: Do not continue escalating basal insulin beyond 0.5 units/kg/day without addressing postprandial hyperglycemia 1
• Do not start with complex regimens: Begin simple (basal only) and intensify only as needed based on glucose patterns 1
• Ensure proper patient education on glucose monitoring, injection technique, insulin storage, hypoglycemia recognition/treatment, and sick day rules before restarting insulin 1
• Continue metformin when adding insulin unless contraindicated 1