Recommended Initial Total Daily Dose (TDD) of Insulin for Type 1 Diabetes
The recommended starting insulin dose for metabolically stable patients with type 1 diabetes is 0.5 units/kg/day, with approximately 50% as basal insulin and 50% as prandial insulin. 1, 2
Initial Insulin Dosing Framework
- For metabolically stable patients with type 1 diabetes, start with 0.5 units/kg/day as the total daily dose (TDD) 1
- The typical range for insulin requirements is 0.4-1.0 units/kg/day, with adjustments needed based on individual factors 1
- Higher insulin doses are often required during puberty, pregnancy, and medical illness 1
- For patients presenting with diabetic ketoacidosis, higher weight-based starting doses may be needed 1
Distribution of Total Daily Dose
- Divide the TDD into approximately 50% basal insulin and 50% prandial insulin 1, 2
- For basal insulin, administer as a single daily injection of long-acting insulin analog 1
- For prandial insulin, divide the remaining 50% of TDD into pre-meal boluses of rapid-acting insulin 1, 2
- More recent research suggests a lower basal insulin requirement of approximately 24-30% of TDD in some patients 3, 4
Factors Affecting Insulin Requirements
- Age: Younger patients and adolescents typically require higher insulin doses; basal insulin requirements decrease with age 4
- Body mass index (BMI): Higher BMI correlates with higher basal insulin requirements as a percentage of TDD 4
- Physical activity: Adjust doses for anticipated exercise 1
- Meal content: Consider carbohydrate, fat, and protein content 1
Insulin Adjustment Formulas
- Carbohydrate-to-insulin ratio (CIR) can be estimated using:
- Correction factor (CF) can be estimated using CF = 1500/TDD 5
- Some research suggests the relationship: 100/TBD = ICR = CF/4.5 6
Delivery Methods
- Most patients with type 1 diabetes should be treated with multiple daily injections (MDI) of prandial and basal insulin, or continuous subcutaneous insulin infusion (CSII) 1
- Rapid-acting insulin analogs should be used to reduce hypoglycemia risk 1
- Consider educating patients on matching prandial insulin doses to carbohydrate intake, premeal blood glucose levels, and anticipated physical activity 1
Common Pitfalls to Avoid
- Underestimating initial insulin requirements in adolescents or during illness 1
- Using outdated formulas that may overestimate basal insulin needs and underestimate bolus requirements 5
- Not adjusting insulin doses for changes in physical activity, meal patterns, or during acute illness 7
- Failing to provide education on proper injection technique, which can lead to variable absorption 2
- Overlooking the importance of consistent timing for basal insulin administration 2
Special Considerations
- In patients with chronic kidney disease stage 5, consider reducing the total daily insulin dose by 35-40% 1
- For patients on hemodialysis, consider reducing basal insulin dose by 25% on pre-hemodialysis days 1
- When switching from twice-daily NPH insulin to once-daily glargine, start with 80% of the total NPH dosage 7