What are the steps for converting a patient to insulin therapy?

Steps for Converting a Patient to Insulin Therapy

The most effective approach to insulin conversion involves starting with basal insulin at 10 units per day or 0.1-0.2 units/kg per day, with systematic titration based on fasting glucose targets, followed by stepwise addition of prandial insulin if needed. 1

Initial Assessment and Decision to Start Insulin

• Consider insulin as first injectable therapy when symptoms of hyperglycemia are present, A1C >10%, blood glucose ≥300 mg/dL, or when type 1 diabetes is suspected 1
• For patients with type 2 diabetes, insulin is indicated when oral medications fail to achieve glycemic targets, during acute illness, surgery, pregnancy, or when contraindications to other agents exist 2

Step 1: Initiate Basal Insulin

• Starting dose: 10 units per day OR 0.1-0.2 units/kg per day 1
• Insulin options:
  • Long-acting analogs (glargine, detemir, degludec) - preferred due to lower risk of hypoglycemia 1
  • NPH insulin - typically administered at bedtime, more affordable but higher hypoglycemia risk 1
• Set fasting plasma glucose (FPG) target based on individualized glycemic goals 1

Step 2: Titration of Basal Insulin

• Choose evidence-based titration algorithm: increase by 2 units every 3 days until FPG target is reached without hypoglycemia 1
• If hypoglycemia occurs, determine cause; if no clear reason, reduce dose by 10-20% 1
• Assess adequacy of basal insulin at every visit, looking for signs of overbasalization (elevated bedtime-to-morning differential, hypoglycemia, high glucose variability) 1

Step 3: Consider GLP-1 RA Addition if A1C Remains Above Target

• If A1C remains above goal despite optimized basal insulin, consider adding GLP-1 RA before adding prandial insulin 1
• Fixed-ratio combination products (IDegLira or iGlarLixi) may be appropriate options 1

Step 4: Add Prandial Insulin if A1C Remains Above Target

• Starting dose: 4 units per day or 10% of basal insulin dose 1
• Administration: Start with one dose at the largest meal or meal with greatest postprandial excursion 1
• Titration: Increase by 1-2 units or 10-15% twice weekly based on postprandial glucose values 1
• If A1C <8%, consider lowering the basal dose by 4 units or 10% when adding prandial insulin 1

Step 5: Intensify to Multiple Daily Injections if Needed

For patients on bedtime NPH, consider converting to twice-daily NPH:

• Total dose = 80% of current bedtime NPH dose 1
• 2/3 given in morning, 1/3 given at bedtime 1
• Titrate based on individualized needs 1

For full basal-bolus regimen:

• Add prandial insulin before each meal 1
• Add 4 units of rapid/short-acting insulin to each meal or 10% of reduced NPH dose 1
• Titrate each component separately based on glucose patterns 1

Special Considerations

• Insulin storage: Store unopened insulin in refrigerator; opened insulin can be kept at room temperature for 28 days 3
• Injection technique: Use shortest needles available (4-mm pen, 6-mm syringe); rotate injection sites to prevent lipohypertrophy 2
• Monitoring: Use fasting glucose values to titrate basal insulin and postprandial values to titrate mealtime insulin 2
• Hypoglycemia prevention: Prescribe glucagon for emergency hypoglycemia; educate on recognition and treatment of hypoglycemia 1

Transitioning from IV to Subcutaneous Insulin

For hospitalized patients transitioning from IV to subcutaneous insulin:

• Calculate total daily dose based on IV requirements: use 1/2 of the total 24-hour IV insulin dose 1
• Divide this amount by 3 for prandial insulin doses 1
• Start subcutaneous insulin 1-2 hours before discontinuing IV insulin to ensure adequate insulin coverage 1

Common Pitfalls to Avoid

• Therapeutic inertia: Delaying insulin initiation or intensification despite suboptimal control 4
• Overbasalization: Continuously increasing basal insulin without adding prandial coverage when needed 1
• Inadequate education: Failing to properly educate patients on injection technique, glucose monitoring, and hypoglycemia management 1
• Abrupt discontinuation: Never abruptly discontinue oral medications when starting insulin therapy due to risk of rebound hyperglycemia 2

By following this systematic approach to insulin initiation and titration, clinicians can effectively transition patients to insulin therapy while minimizing risks of hypoglycemia and optimizing glycemic control.