Managing diabetes effectively often involves precise insulin dosing. This calculator provides an estimate for bolus insulin (rapid-acting or short-acting) based on current blood glucose levels, target blood glucose, carbohydrate intake, and individual insulin response factors.
Important Note: This calculator is an educational tool and should NOT replace the advice of a qualified healthcare professional. Insulin needs can vary significantly based on many factors, including activity levels, illness, stress, and other medications. Always consult with your doctor or diabetes educator to determine your personal insulin regimen.
How the Calculation Works:
The recommended insulin dose is typically calculated as the sum of two main components:
Correction Dose: This is the amount of insulin needed to bring elevated blood glucose levels down to the target range. It's calculated using the Insulin Sensitivity Factor (ISF).
Mealtime (Bolus) Dose: This is the amount of insulin needed to cover the carbohydrates consumed during a meal. It's calculated using the Carbohydrate-to-Insulin Ratio (CIR).
Total Recommended Bolus Dose = Correction Dose + Mealtime Dose
Understanding the Inputs:
Current Blood Glucose (mg/dL): Your blood glucose reading from a meter or continuous glucose monitor (CGM).
Target Blood Glucose (mg/dL): The blood glucose level you aim to achieve. This is often set by your healthcare provider.
Insulin Sensitivity Factor (ISF): Also known as the "correction factor" or "i:factor". This number indicates how many mg/dL one unit of rapid-acting or short-acting insulin will lower your blood glucose. For example, an ISF of 50 means one unit of insulin is expected to lower blood glucose by 50 mg/dL.
Carbohydrate Intake (grams): The estimated amount of carbohydrates in the meal you are about to eat.
Carbohydrate-to-Insulin Ratio (CIR): Also known as the "insulin-to-carb ratio" or "i:c ratio". This number indicates how many grams of carbohydrates one unit of insulin can cover. For example, a ratio of 10:1 means one unit of insulin is expected to cover 10 grams of carbohydrates.
Insulin Type:
Rapid-Acting Insulin: (e.g., Humalog, Novolog, Apidra) typically used for corrections and meal boluses. Works within 15-30 minutes.
Short-Acting Insulin: (e.g., Regular insulin like Humulin R, Novolin R) also used for corrections and meal boluses but has a slower onset and longer duration than rapid-acting.
The calculation remains the same for both types when determining the bolus dose, but the timing of when to take the insulin and its duration of action differ.
Example Calculation:
Let's say a person with type 1 diabetes has the following values:
Current Blood Glucose: 210 mg/dL
Target Blood Glucose: 120 mg/dL
Insulin Sensitivity Factor (ISF): 40 mg/dL per unit
Carbohydrate Intake: 60 grams
Carbohydrate-to-Insulin Ratio (CIR): 12 grams per unit
Total Recommended Bolus Dose:
2.25 units (Correction) + 5 units (Mealtime) = 7.25 units
This individual would be recommended to take approximately 7.25 units of rapid-acting insulin. Adjustments might be made based on individual clinical judgment and other influencing factors.
function calculateInsulinDose() {
var bloodGlucose = parseFloat(document.getElementById("bloodGlucose").value);
var targetGlucose = parseFloat(document.getElementById("targetGlucose").value);
var insulinSensitivityFactor = parseFloat(document.getElementById("insulinSensitivityFactor").value);
var carbIntake = parseFloat(document.getElementById("carbIntake").value);
var carbRatio = parseFloat(document.getElementById("carbRatio").value);
var insulinType = document.getElementById("insulinType").value; // Not used in core calculation but could be for future features
var correctionDose = 0;
var mealtimeDose = 0;
var totalDose = 0;
// Validate inputs
if (isNaN(bloodGlucose) || isNaN(targetGlucose) || isNaN(insulinSensitivityFactor) || isNaN(carbIntake) || isNaN(carbRatio)) {
document.getElementById("result").innerText = "Please enter valid numbers for all fields.";
return;
}
// Calculate Correction Dose
if (insulinSensitivityFactor > 0) {
var glucoseDifference = bloodGlucose – targetGlucose;
if (glucoseDifference > 0) { // Only calculate correction if BG is above target
correctionDose = glucoseDifference / insulinSensitivityFactor;
}
} else {
// Handle case where ISF is 0 or invalid, though ISF is typically positive.
// For safety, we might just not add a correction dose if ISF is not a valid positive number.
correctionDose = 0;
}
// Calculate Mealtime Dose
if (carbRatio > 0) {
mealtimeDose = carbIntake / carbRatio;
} else {
// Handle case where CIR is 0 or invalid.
mealtimeDose = 0;
}
// Calculate Total Dose
totalDose = correctionDose + mealtimeDose;
// Round to a reasonable number of decimal places (e.g., 0.5 or 1 unit depending on clinical practice)
// For this example, let's round to two decimal places.
totalDose = Math.round(totalDose * 100) / 100;
// Display result
if (totalDose < 0) totalDose = 0; // Dose cannot be negative
document.getElementById("result").innerText = totalDose.toFixed(2);
}