How much insulin do I need per gram of carbohydrate?

Toby Smithson
Nutrition & Dietetics
The insulin to carbohydrate (I:C) equation takes into account the amount of 1 unit of rapid active insulin is needed to cover or match a specific amount of carbohydrate ingested. This ratio is individualized to the person's sensitivity to insulin so the numbers will vary. A toddler may need 1 unit to every 30 grams of carbohydrate while an adult who has some insulin resisitance or not sensitive to insulin may require as much as 1 unit of insulin to every 5 grams of carbohydrate. It is best to work with your endocrinologist and diabetes educator to figure out how much insulin you need for each gram of carbohydrate. There are several methods to calculate the I:C ratio. Here is one of them: based on your weight adn total daily insulin dose; multiply 2.8 X weight in pounds and divide by your total daily dose of insulin to get your I:C ratio.
People with type 1 diabetes and people with type 2 diabetes who take insulin can work with their dietitian or diabetes educator to come up with a plan for how much insulin to inject per gram of carbohydrate.  In general, 1 unit of insulin will cover up to 20 grams of carbohydrate. You also need to find out how this applies to you. You need to monitor your blood glucose frequently. You will need to adjust the amounts of rapid-acting insulin given before each meal in order to cover the carbohydrates in your meal, lower a high blood glucose level not sufficiently lowered by the previous rapid-acting insulin injection, or anticipate the rise in blood glucose caused by the next meal.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.