The most common way to calculate insulin resistance at home is with a formula called HOMA-IR, which uses two numbers from a simple fasting blood test: your fasting glucose and your fasting insulin. Once you have those values, the math takes about 30 seconds. There are also other indices and ratios that estimate insulin resistance, each with different trade-offs between accuracy and convenience.
The HOMA-IR Formula
HOMA-IR stands for Homeostatic Model Assessment of Insulin Resistance. It’s the most widely used calculation in both clinical practice and research. The formula is:
HOMA-IR = (fasting insulin × fasting glucose) / 405
This version uses fasting insulin in μIU/mL and fasting glucose in mg/dL, the standard units in the United States. If your lab reports glucose in mmol/L (common in the UK, Canada, and Australia), the formula changes slightly:
HOMA-IR = (fasting insulin × fasting glucose) / 22.5
A healthy HOMA-IR score generally falls below 1.0. Scores between 1.0 and 2.0 suggest early or mild insulin resistance. A score above 2.0 is widely considered a clear sign of insulin resistance, though some researchers place the threshold at 2.5 or higher depending on the population studied. The higher the number, the more resistant your cells are to insulin’s effects.
What You Need Before Calculating
Both numbers in the HOMA-IR formula come from a single fasting blood draw. You’ll need to fast for 8 to 12 hours beforehand, meaning no food or drinks other than water. If you take biotin supplements (vitamin B7), stop them at least one day before your test, as biotin can interfere with certain lab assays.
Most standard metabolic panels include fasting glucose but not fasting insulin. You may need to specifically request a fasting insulin test. Some doctors order it routinely when screening for metabolic syndrome or prediabetes, but others don’t. If your lab results list both values, you can plug them into the formula yourself.
Unit Conversions
Labs around the world report glucose and insulin in different units, so getting the formula right depends on checking your lab report carefully. To convert between common units:
- Glucose: mg/dL × 0.0555 = mmol/L
- Insulin: μIU/mL × 6 = pmol/L
If your glucose is in mmol/L and your insulin is in μIU/mL, use the version of the formula that divides by 22.5. If both are in the more common U.S. units (mg/dL for glucose, μIU/mL for insulin), divide by 405.
The QUICKI Index
QUICKI, or the Quantitative Insulin Sensitivity Check Index, is another formula that uses the same two blood values but applies a logarithmic transformation. It was developed as a more mathematically robust alternative to HOMA-IR, and some researchers consider it slightly better at tracking changes in insulin sensitivity over time.
The formula is:
QUICKI = 1 / [log(fasting insulin) + log(fasting glucose)]
Here, fasting insulin is in μIU/mL and fasting glucose is in mg/dL. Unlike HOMA-IR, where higher numbers mean more resistance, QUICKI works in reverse: lower scores indicate greater insulin resistance. Published reference values from the Journal of Clinical Endocrinology & Metabolism provide a useful benchmark. Non-obese individuals averaged 0.382, obese individuals averaged 0.331, and people with diabetes averaged 0.304.
The Triglyceride-to-HDL Ratio
If you don’t have a fasting insulin level but do have a standard lipid panel, the triglyceride-to-HDL cholesterol ratio offers a rough estimate of insulin resistance. You simply divide your triglycerides by your HDL cholesterol (both in mg/dL).
Research published by the American Diabetes Association found that a ratio above 2.27 was associated with roughly six times the odds of being insulin resistant in white subjects. This ratio is less precise than HOMA-IR, but it’s useful as a screening tool because lipid panels are ordered far more frequently than fasting insulin tests. The ratio tends to be less reliable in Black populations, where triglyceride levels run lower on average for genetic reasons that don’t necessarily reflect better insulin sensitivity.
HOMA2: The Updated Computer Model
The original HOMA-IR formula is a simplified approximation. A more sophisticated version, called HOMA2, was developed to account for the nonlinear relationship between glucose and insulin at higher concentrations. HOMA2 can also incorporate C-peptide levels (a byproduct of insulin production) alongside or instead of insulin, which improves differentiation between normal and diabetic ranges.
You can’t calculate HOMA2 by hand. It requires a computer model available through the University of Oxford’s Diabetes Trials Unit website. If your doctor uses HOMA2 instead of the original formula, the output is scaled so that a score of 1.0 represents a “normal” reference individual. Scores above 1.0 indicate increasing resistance.
The Gold Standard: Clamp Testing
All the formulas above are estimates. The true gold standard for measuring insulin sensitivity is a procedure called the euglycemic clamp, used almost exclusively in research settings. During the test, insulin is infused intravenously at a fixed rate while glucose is simultaneously dripped in and adjusted every 5 to 10 minutes to keep blood sugar locked in a narrow target range. The amount of glucose needed to maintain that target during a steady-state window (typically between 80 and 120 minutes) directly measures how sensitive your tissues are to insulin.
This test is expensive, time-consuming, and requires clinical supervision. It exists to validate simpler tools like HOMA-IR, not to screen individual patients. For practical purposes, the formulas described above provide reliable enough estimates to guide clinical decisions.
What Your Score Actually Tells You
A single HOMA-IR or QUICKI score is a snapshot, not a diagnosis. Insulin resistance exists on a spectrum, and your score can shift significantly based on sleep, stress, recent exercise, illness, and what you ate the day before your fast. Tracking the number over time, ideally under consistent conditions, gives a more meaningful picture than any single result.
Insulin resistance typically develops years before blood sugar rises enough to trigger a prediabetes or diabetes diagnosis. That’s what makes these calculations valuable: fasting glucose alone can look perfectly normal while insulin levels are already climbing to compensate. By the time glucose starts rising, your pancreas has often been overproducing insulin for a long time. Calculating HOMA-IR captures that earlier stage, when lifestyle changes like improved diet, regular physical activity, and weight loss are most effective at reversing the trajectory.