Ordering Regular Insulin for Home Use
For home use, regular (human) insulin should be ordered as part of a scheduled basal-bolus regimen, not as monotherapy, with typical dosing of 1 unit per 10-15 grams of carbohydrate given 30-45 minutes before meals. 1
Key Prescribing Specifications
Insulin Type and Formulation
- Order human regular insulin U-100 vials (e.g., Humulin R, Novolin R) as the standard concentration 1
- Regular insulin is significantly less expensive than rapid-acting analogs, with costs as low as $165 per 1,000 units compared to $330-447 for analogs 1
Administration Timing
- Regular insulin must be given 30-45 minutes before meals, not at mealtime like rapid-acting analogs 1
- Duration of action is 6-8 hours, which increases postprandial hypoglycemia risk compared to rapid-acting analogs 2
Dosing Algorithms
Initial Prandial Dosing
- Start with 4 units before the largest meal or 10% of the basal insulin dose 1
- Alternative calculation: 1 unit per 10-15 grams of carbohydrate in the meal 1
Titration Schedule
- Increase by 1-2 units or 10-15% every 3 days based on 2-hour postprandial glucose readings 1
- Target postprandial glucose <180 mg/dL 1
- If hypoglycemia occurs, reduce dose by 10-20% immediately 1
Correction Dosing
- For patients not counting carbohydrates, use simplified approach: 1
- Add 2 units if premeal glucose >250 mg/dL
- Add 4 units if premeal glucose >350 mg/dL
- Calculate individualized correction factor: 1500 ÷ total daily insulin dose 1
Essential Prescription Components
Complete Order Should Include:
- Basal insulin component: Regular insulin cannot serve as sole therapy 1, 3
- Specific meal timing: Document which meals require coverage 1
- Blood glucose monitoring: Check premeal and 2-hour postprandial values 1
- Hypoglycemia treatment supplies: 15 grams fast-acting carbohydrate 1
Sample Prescription Format:
Regular insulin (Humulin R or Novolin R) U-100 vial
Dose: [X] units subcutaneously 30-45 minutes before [breakfast/lunch/dinner]
Plus correction: Add 2 units if glucose >250 mg/dL, 4 units if >350 mg/dL
Dispense: [quantity] with syringes/pen needles
Refills: [number]Critical Pitfalls to Avoid
Timing Errors
- Never order regular insulin to be given at mealtime (0-15 minutes before)—this timing is only appropriate for rapid-acting analogs 1, 2
- Never give regular insulin at bedtime as correction—the 6-8 hour duration causes nocturnal hypoglycemia 1
Monotherapy Mistakes
- Never prescribe regular insulin as sliding scale monotherapy—this approach is explicitly condemned by all major guidelines and leads to dangerous glucose fluctuations 1, 3, 4
- Regular insulin must be part of a scheduled regimen with basal insulin coverage 1, 3
Combination Therapy Errors
- Continue metformin unless contraindicated when adding insulin—this reduces insulin requirements and weight gain 1, 4
- Consider discontinuing sulfonylureas when starting prandial insulin to prevent hypoglycemia 1, 5
Patient Education Requirements
Administration Technique
- Inject 30-45 minutes before eating to match insulin peak with meal absorption 1
- Use shortest needles available (4-mm pen or 6-mm syringe) to avoid intramuscular injection 4
- Rotate injection sites to prevent lipohypertrophy 4
Monitoring Instructions
- Check premeal glucose to calculate correction doses 1
- Check 2-hour postprandial glucose to assess meal coverage adequacy 1
- Treat any glucose <70 mg/dL immediately with 15 grams fast-acting carbohydrate 1
Storage and Handling
- Store unopened vials in refrigerator 1
- Opened vials stable at room temperature for 28-31 days 1
- Protect from extreme heat and direct sunlight 1
Special Considerations
When Regular Insulin Is Preferred
- Cost constraints: Regular insulin costs 50% less than rapid-acting analogs 1
- Continuous tube feeding: Give every 6 hours to match continuous carbohydrate delivery 1, 3
- Parenteral nutrition: Can be added directly to TPN solution 1