Insulin Calculations for Type 1 Diabetes Insulin-to-Carb Ratio (ICR) 500/TDD = #g of carbs covered by I unit of rapid-acting insulin Insulin Sensitivity Factor (ISF) 1800/TDD = #mg/dL of glucose lowered by 1 unit of rapid-acting insulin Here's the 2 primary calculations used in dosing insulin for patients with type 1 diabetes. The ICR tells us how many grams of carbs are covered by 1 unit of mealtime insulin, while the ISF tells us how much of a blood sugar drop can be expected by 1 unit of mealtime insulin. This can be utilized in 2 main ways. One way is for patients to calculate how many carbs they will eat in a meal, use the ICR to calculate how many units needed to cover the meal, then check BG and add on any additional units of insulin to "correct" the BG back down to goal. Another way is for patients who have a fairly standard mealtime insulin dose, but will be eating additional carbs in a meal. They would calculate how many additional carbs (more than usual), then add the insulin to their normal mealtime dose. They will also add an additional amount with the ISF if needed. Jarred Prudencio, PharmD - https://www.instagram.com/ambcarerx #Insulin #Calculation #ICR #ISF #CarbRatio #SensitivityFactor #Type1 #Diabetes #DM1 #Pharmacology #Endocrinology