There are two primary methods for calculating total daily insulin dose (TDD): by adding up current doses or using a weight-based formula.
Method 1: Tallying existing doses
If a patient already taking insulin, the most accurate way to calculate the TDD is to add up all the insulin they take over a 24-hour period.
- For injections: Add together all long-acting (basal) insulin and mealtime (bolus) rapid-acting insulin doses.
- For insulin pumps: Check pump's settings for the calculated average TDD over the last 7 days.
Example:
If a patient takes 25 units of basal insulin daily and 8 units of mealtime insulin with each of your three meals, your TDD is calculated as:
- Basal insulin: 25 units
- Mealtime insulin: 8 units x 3 meals = 24 units
- Total Daily Dose: 25 + 24 = 49 units
Method 2: Weight-based formulas
For patients new to insulin therapy or for initial estimates, healthcare providers may use weight-based calculations as a starting point.
- Weight in pounds can be used in a calculation to help estimate a starting total daily dose.
- Similarly, weight in kilograms can also be used in a calculation for an estimated total daily dose.
How the Total Daily Dose is Split Between Basal and Bolus Insulin
Once a total daily dose is established, it is typically split between basal (background) and bolus (mealtime) insulin.
- A common approach involves allocating a portion of the total daily dose to basal insulin and the remaining portion to bolus insulin.
- The bolus portion is then often distributed among meals.
Factors That Influence Your Insulin Needs
Multiple factors can affect an individual's insulin needs, making the required dose highly individualized. These can include:
- Insulin resistance: Higher resistance may necessitate a greater amount of insulin.
- Type of diabetes: Type 1 diabetes typically requires more insulin replacement than Type 2.
- Diet: Variations in carbohydrate intake can influence insulin requirements.
- Physical activity: Exercise generally increases insulin sensitivity, which may lead to a need for less insulin.
- Weight fluctuations: Changes in body weight can impact insulin needs.
- Illness and stress: These factors can cause temporary elevations in blood sugar levels.
Sources:
https://patient.info/medicine/insulin