HOMA-IR & Fasting Insulin: Detect Insulin Resistance Early

(Catching insulin resistance years before diabetes)

Part 1 – Clinical Endocrinology Deep Dive

🔍 What is Fasting Insulin?

• Definition: Plasma insulin concentration measured after an overnight fast (8–10 hours).

• Purpose: Detects hyperinsulinemia, often the earliest biochemical sign of insulin resistance (Stage 0).

• Why it matters:

  • Fasting glucose may remain normal for years, but fasting insulin rises early.

  • Helps identify high-risk patients long before glucose abnormalities appear.

🧪 What is HOMA-IR?

Formula:

$$\text{HOMA-IR} = \frac{\text{Fasting Glucose (mg/dL)} \times \text{Fasting Insulin (μIU/mL)}}{405}$$

(If glucose is in mmol/L, divide by 22.5 instead of 405.)

📊 Indian-Context Interpretation Cut-offs

Note: Indians develop insulin resistance at lower BMI and waist size — use slightly lower cut-offs than Western references.

⚠️ When to Order

• Central obesity, fatty liver, PCOS, family history of diabetes

• Unexplained weight gain, metabolic syndrome features

• Normal fasting glucose but strong risk profile

🔬 Limitations

• Not useful if patient is on exogenous insulin therapy

• Affected by acute illness, infection, or steroid use

• Must be taken fasting, ideally morning, in stable condition
  

Part 2 – Patient-Friendly Version

Why Test Fasting Insulin & HOMA-IR Even if Sugar is Normal?

Think of insulin as money you spend so sugar can enter your cells.

• In early diabetes, your body starts spending more and more insulin to get the same job done.

• Blood sugar still looks “normal” on reports, but the effort (insulin levels) is going up.

• HOMA-IR is the score that tells us how resistant your body is to insulin.

🗂 Example HOMA-IR Interpretation

💡 Clinical Pearl:
In India, a HOMA-IR > 2 is already a red flag — even if fasting sugar and HbA1c look perfect.

Also Read: Dawn Phenomenon vs Somogyi Effect: Why Morning Sugar Spikes

FAQs

1. Can I have high HOMA-IR with normal sugar?
Yes. This is exactly the “hidden stage” we want to detect early.

2. How often should I check HOMA-IR?
If you have risk factors, once a year is enough for prevention tracking.

3. What lowers HOMA-IR?
Exercise (especially strength training), high-fiber diet, weight loss, stress control, and proper sleep.

4. Is HOMA-IR part of regular diabetes checkups?
No — it’s an advanced test and is usually ordered if you have high-risk features.

5. Can medication help if HOMA-IR is high but sugar is normal?
Sometimes — in very high-risk cases, doctors may start early intervention like metformin, but lifestyle change is always the first step.