1. What is HOMA-IR (C-Peptide)?

HOMA-IR (Homeostatic Model Assessment for Insulin Resistance) using C-Peptide is a method to estimate insulin resistance. C-Peptide is a more stable marker than insulin as it has a longer half-life and shows less fluctuation in the bloodstream.

2. How Does the Calculator Work?

The calculator uses the HOMA-IR (CP) equation:

Where:

• Fasting Glucose — Measured in mmol/L
• Fasting C-Peptide — Measured in nmol/L
• 22.5 — Constant derived from normal values

Explanation: This equation provides an estimate of insulin resistance by combining fasting glucose and C-peptide measurements, which reflect pancreatic beta-cell function and insulin production.

3. Importance of HOMA-IR Calculation

Details: Assessing insulin resistance is crucial for identifying individuals at risk for type 2 diabetes, metabolic syndrome, and cardiovascular diseases. The C-peptide version offers advantages in stability and reliability compared to insulin-based calculations.

4. Using the Calculator

Tips: Enter fasting glucose in mmol/L and fasting C-peptide in nmol/L. Both values should be from the same fasting blood sample for accurate results. Normal HOMA-IR values typically range from 0.5-1.4, with values above 2.0 indicating significant insulin resistance.

5. Frequently Asked Questions (FAQ)

Q1: Why use C-peptide instead of insulin for HOMA-IR?
A: C-peptide has a longer half-life than insulin, shows less fluctuation, and isn't extracted by the liver, making it a more stable marker of insulin secretion.

Q2: What are normal HOMA-IR values?
A: Normal HOMA-IR values typically range from 0.5-1.4. Values between 1.9-2.9 indicate moderate insulin resistance, while values above 2.9 indicate severe insulin resistance.

Q3: When should the blood test be performed?
A: After an 8-12 hour fast, typically in the morning. Avoid testing after illness, surgery, or significant changes in diet or medication.

Q4: Are there limitations to this calculation?
A: HOMA-IR provides an estimate, not a direct measurement of insulin resistance. It may be less accurate in certain conditions like liver disease, renal impairment, or in patients using certain medications.

Q5: How does this compare to the insulin-based HOMA-IR?
A: Both methods assess insulin resistance, but the C-peptide version may be more reliable in certain clinical situations, especially when insulin assays are inconsistent or in patients with insulin antibodies.