Diabetes Carb Calculator

With a 1:10 insulin to carb ratio, 60 g of carbs requires 6 units. With a 1:15 ratio, the same meal needs 4 units. Your endocrinologist determines your personal I:C ratio, which often varies by meal time (breakfast ratios are usually tighter than dinner).

An I:C ratio is how many grams of carbs are covered by 1 unit of rapid-acting insulin. A 1:10 ratio means 1 unit covers 10 g of carbs. Typical adult ratios are 1:10 to 1:15. Children and adolescents often need tighter ratios like 1:5 to 1:10.

Subtract your target blood sugar from your current reading, then divide by your correction factor. If your BG is 180, target is 110, and correction factor is 50: (180 - 110) / 50 = 1.4 units of correction insulin. Add this to your carb bolus for the total mealtime dose.

Most endocrinologists recommend counting total carbs for accuracy, especially for tighter blood sugar control. Subtracting fiber is acceptable if total fiber is over 5 g per serving and the dose change is meaningful (more than 1 g of fiber per gram of carbs). Always confirm with your diabetes care team.

Correction factors usually fall between 30 and 80 mg/dL per unit (1.7 to 4.4 mmol/L per unit). It is calculated from total daily insulin: 1,800 / Total Daily Dose for rapid-acting insulin, or 1,500 / TDD for older formulas. A higher correction factor means each unit drops blood sugar more.

Aim for plus or minus 5 g per meal. Studies show carb counting within this margin produces meaningful differences in post-meal blood sugar. Weighing food on a kitchen scale, reading nutrition labels, and using consistent serving sizes all improve accuracy.

No. This is an educational tool that uses standard formulas, but it cannot account for your specific insulin sensitivity, exercise, illness, stress, hormonal cycles, or medication interactions. Always confirm dosing with your endocrinologist or certified diabetes educator before changing your insulin plan.

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