What is the total daily dose of insulin?

The **total daily dose (TDD)** is the sum of all insulin given in 24 hours — basal plus all bolus doses. For adults with T1DM, the starting estimate is *0.4–0.5 U/kg/day*; for T2DM on insulin initiation, *0.2–0.3 U/kg/day* of basal insulin is a typical starting point.

What is the insulin sensitivity factor (ISF)?

The **insulin sensitivity factor (ISF)**, also called the correction factor, estimates how much 1 unit of rapid-acting insulin will lower blood glucose. In SI units: *ISF = 100 ÷ TDD (mmol/L per unit)*. In US units: *ISF = 1,800 ÷ TDD (mg/dL per unit)*.

What is the insulin-to-carbohydrate ratio (ICR)?

The **ICR** estimates how many grams of carbohydrate 1 unit of rapid-acting insulin covers. A common starting estimate is the *500 rule*: ICR = 500 ÷ TDD. For a TDD of 50 units: ICR = 500 ÷ 50 = *10 g/unit* (1 unit covers 10 g of carbohydrate).

How do I calculate a correction dose?

**Correction dose (units) = (Current BG − Target BG) ÷ ISF**. Subtract any *insulin-on-board* (IOB) from a recent bolus before administering a correction. Never give a correction that would result in a negative net dose.

What is the difference between basal and bolus insulin?

**Basal insulin** (long-acting) covers background glucose production between meals and overnight — typically *50% of TDD*. **Bolus insulin** (rapid-acting) is given with meals to handle dietary carbohydrate and to correct episodic hyperglycaemia — typically *50% of TDD divided among meals*.

Can I adjust my insulin dose myself?

Structured *dose titration protocols* (e.g., adjusting bedtime basal by 1–2 units every 3 days based on fasting glucose) can be safely self-managed with proper education. However, significant regimen changes should always involve the **diabetes care team**, particularly in unstable or complex situations.

What blood glucose level requires a correction dose?

Correction doses are typically given when blood glucose is **above the personal target** (usually 6–8 mmol/L or 108–144 mg/dL fasting). The threshold and target vary by individual. Never correct below the target or without checking for active IOB from a recent bolus.

Endocrinology · Diabetes Management

Insulin Dose
Calculator

⚕️

⚠️ High-Risk Medication — Important Notice

Last reviewed: March 2026

Insulin is a high-alert medication. Dosing errors can cause severe hypoglycaemia and are potentially life-threatening.

This tool is for educational and reference purposes only. ICR and ISF estimates (500-rule, 1800-rule) are population starting points — they must be individualised and verified by the treating diabetes care team.

Do not use this tool as the sole basis for insulin dosing decisions. All calculations must be reviewed by a qualified clinician before implementation.

I understand this is educational only and will not use these calculations clinically without clinician review.