What is the carbohydrate correction factor for an insulin pump?

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Dainyal Siddiqui, MD

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Manuel Jimenez, MD

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Franz Pierre-Louis, MD

Infectious Disease

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Last updated: April 25, 2025 • View editorial policy

From the Guidelines

The carbohydrate correction factor for an insulin pump, also known as the insulin-to-carbohydrate ratio (ICR), is typically calculated based on the amount of carbohydrate ingested and the carbohydrate to insulin ratio, which is defined as the amount of carbohydrate (in g) covered by 1 unit of insulin, as described in the study published in the British Journal of Anaesthesia 1. This ratio is highly individualized and should be determined with your healthcare provider. To calculate your personal ICR, the study suggests that it is a reflection of the patient’s sensitivity to insulin, and is calculated from the total daily dose of insulin 1. For example, with an example ratio of 1:10, for every 10 g of carbohydrate ingested 1 unit of insulin will be required, as mentioned in the study 1. Factors affecting your ICR include insulin sensitivity, time of day, physical activity, stress levels, and hormonal changes, and your insulin pump should be programmed with this ratio to calculate bolus doses automatically when you input carbohydrate amounts. Regular blood glucose monitoring is essential to evaluate the effectiveness of your ICR, and you should adjust it with your healthcare provider if you consistently experience high or low blood glucose levels after meals. The ICR works alongside your correction factor (sensitivity factor) to determine total insulin doses needed for both food coverage and blood glucose corrections, as the insulin sensitivity factor is an individualized measure of by how much the blood glucose will decrease on infusion of 1 unit of insulin, as described in the study 1. Some people find they require more insulin per carbohydrate in the mornings when some of the counter regulatory hormones are still high, and this ratio can vary throughout the day and can be set at different levels for different time blocks, as mentioned in the study 1. All these parameters are calculated at the start of insulin pump therapy and rather than being fixed for the lifetime of the pump are subject to change according to physiological changes such as weight, exercise, menstruation, and usually people on insulin pump therapy will attend, in the maintenance phase of their therapy, a diabetes clinic every 3–6 months with a team specialized in pump therapy where changes to basal rates, insulin to carbohydrate ratios and insulin sensitivity factors or correction factors can be reviewed 1.

From the Research

Carbohydrate Correction Factor for Insulin Pump

  • The carbohydrate-to-insulin ratio (CIR) is a crucial factor in determining the insulin dose for patients with type 1 diabetes using an insulin pump 2.
  • A study published in 2012 found that CIR can be estimated from the formula CIR=300/TDD at breakfast or CIR=400/TDD at lunch and supper in type 1 diabetes patients 2.
  • Another study published in 2025 examined insulin pump settings for insulin-to-carbohydrate ratios (ICRs) and insulin sensitivity factors (ISFs) in pediatric patients with type 1 diabetes, considering diurnal variation, age, sex, and body mass index (BMI) 3.
  • The study found that older children required more insulin, with lower ICRs and ISFs, and that insulin requirements peaked in the morning with the lowest ICR and ISF 3.
  • A 2011 study presented an algorithm for determining the best basal-bolus combination for postprandial glucose control in insulin pump therapy, which takes into account the current glycemic state of the patient and the meal to be ingested 4.
  • A 2008 study analyzed guidelines for basal-bolus insulin dosing, including basal insulin, correction factor, and carbohydrate-to-insulin ratio, and found that the accurate insulin management (AIM) system provided a consistent and convenient means of estimating insulin-dosing variables for patients with type 1 diabetes 5.
  • A 2015 study compared the feasibility and effectiveness of using glycaemic load counting (GLC) versus carbohydrate counting (CC) for prandial insulin dosing in patients with type 1 diabetes on insulin pump, and found that GLC may improve postprandial glucose control in people with T1D 6.

Key Findings

  • CIR can be estimated from the formula CIR=300/TDD at breakfast or CIR=400/TDD at lunch and supper in type 1 diabetes patients 2.
  • Insulin requirements peak in the morning with the lowest ICR and ISF in pediatric patients with type 1 diabetes 3.
  • The AIM system provides a consistent and convenient means of estimating insulin-dosing variables for patients with type 1 diabetes 5.
  • GLC may improve postprandial glucose control in people with T1D compared to CC 6.

References

5
Research

Analysis of guidelines for basal-bolus insulin dosing: basal insulin, correction factor, and carbohydrate-to-insulin ratio.

Endocrine practice : official journal of the American College of Endocrinology and the American Association of Clinical Endocrinologists, 2008

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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