Insulin Dosage Calculator

Total mealtime insulin is derived by combining two components: meal insulin (to cover the carbohydrates you are about to eat) and correction insulin (to lower your current blood glucose if it is above your target range). First, meal insulin is calculated by dividing your total carbohydrate grams by your insulin-to-carbohydrate ratio (ICR). Second, correction insulin is calculated by subtracting your target blood sugar from your current blood sugar, then dividing the difference by your insulin sensitivity factor (ISF). If your ICR and ISF are not explicitly known, they can be estimated using your Total Daily Insulin (TDI) via the 500 rule (ICR = 500 / TDI) and the 1800 rule (ISF = 1800 / TDI). Summing these two figures gives your total recommended dose.

Imagine you are preparing for a lunch containing 60 grams of carbohydrates. Your current blood sugar reading is 180 mg/dL, and your target blood sugar is 120 mg/dL. Based on your diabetes management plan, your insulin-to-carbohydrate ratio is 1 unit for every 15 grams of carbs (ICR = 15), and your correction factor is 1 unit of insulin for every 30 mg/dL your blood sugar drops (ISF = 30). First, compute the meal insulin: 60 grams / 15 = 4 units. Next, compute the correction insulin: (180 mg/dL - 120 mg/dL) / 30 = 60 / 30 = 2 units. Finally, add them together: 4 units + 2 units = 6 total units of insulin required for this meal.

Always double-check your carbohydrate measurements using reliable food scales and nutritional labels to prevent dosing errors. Never stack insulin doses too closely together unless explicitly instructed by your endocrinologist, as overlapping action profiles can lead to severe hypoglycemia. Regularly review and update your TDI, ICR, and ISF values with your healthcare provider as your lifestyle, weight, or medical requirements change.