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Blood sugar & insulinQUICKI

QUICKI

A research estimate of insulin sensitivity from fasting insulin and glucose.

Calculated marker8 min read
Reviewed by Atheal’s health team
See how it works

What happens after you eat?

Follow sugar from a meal into your blood, see how insulin helps it into a cell, and why a blood test looks at both.

FIG. 01How insulin and glucose work together
How insulin and glucose work togetherInsulin from the pancreas travels in the blood alongside glucose. Blood tests measure these two substances together. A simplified view of the pancreas, blood and one muscle cell after a meal. Shapes, distances, particle counts and timing are illustrative, not lab values.
  • Sugar (glucose)
  • Insulin
  • Sugar door (GLUT4)
A simplified view of the pancreas, blood and one muscle cell after a meal. Shapes, distances, particle counts and timing are illustrative, not lab values.

Meet your pancreas

This is your pancreas. It makes insulin, a message that helps your body manage blood sugar. Let’s follow that message into the blood.

Blood sugar goes up

After a meal, sugar from digested food enters the blood. As blood sugar rises, it prompts the pancreas to release more insulin.

The pancreas sends insulin

The pancreas releases insulin into the blood. It travels to cells, including muscle cells, and signals them to let glucose in.

The cell opens more sugar doors

The message brings more sugar doors to the cell’s surface. Sugar moves inside, the cell uses it for energy, and blood sugar comes back down.

One blood sample, two readings

A blood test is a snapshot of your blood at that moment. The lab can measure both sugar (glucose) and insulin in the same sample.

Two measurements, one useful relationship

Glucose
How much sugar is in the blood sample.
Insulin
How much insulin is in the blood sample.

A single test is a snapshot. Whether you’d eaten, the time of day, medicines and the reason for testing all help explain the numbers.

What if the cells respond less?

If cells respond less to insulin, does blood sugar always end up higher? Compare the two responses to see what changes.

Cells respond easily A little insulin opens the doors. Blood sugar comes back down, and insulin settles low.

Cells respond less Blood sugar ends up about the same; insulin is what changed. The pancreas sends extra insulin to open the same doors. So a normal sugar result doesn’t tell the whole story, and insulin beside it shows how hard your body is working.

  • Sugar (glucose)
  • Insulin
  • Sugar door (GLUT4)

A simplified view of the pancreas, blood and one muscle cell after a meal. Shapes, distances, particle counts and timing are illustrative, not lab values.

Look closer: how a cell adds sugar doors

The same moment at the scale of the cell’s outer membrane: the insulin receptor, the GLUT4 sugar doors, and the small membrane package that carries them to the surface.

FIG. 01BFrom a signal to your blood test
From a signal to your blood testFollow the signal from the insulin receptor to the GLUT4 transporters at the cell surface. A simplified view of insulin-stimulated uptake in muscle and fat cells. Other tissues handle glucose differently; shapes and timing are illustrative.
  • Insulin
  • Glucose
  • Insulin receptor
  • GLUT4 transporter
A simplified view of insulin-stimulated uptake in muscle and fat cells. Other tissues handle glucose differently; shapes and timing are illustrative.

Let’s look inside a muscle

Muscle cells use glucose for energy. We’ll move closer to one small part of a cell’s outer membrane.

Insulin delivers a message

Outside the cell, insulin attaches to its receptor. The receptor passes a signal inside.

The cell changes its surface

A tiny membrane package joins the cell’s outer membrane. This adds more glucose transporters, called GLUT4, to the surface.

Follow one glucose molecule

Glucose crosses the membrane through a GLUT4 transporter. It follows a different route from insulin’s signal.

The test looks at your blood

The lab measures insulin in a blood sample. Reading it alongside glucose helps explain what the result means.

Two measurements, one useful relationship

Insulin
How much insulin is in the blood sample.
Glucose
How much glucose is in the blood sample.

These blood tests don’t directly show how a muscle cell responds. Meals, medicines and the reason for testing help give the results meaning.

  • Insulin
  • Glucose
  • Insulin receptor
  • GLUT4 transporter

A simplified view of insulin-stimulated uptake in muscle and fat cells. Other tissues handle glucose differently; shapes and timing are illustrative.

Key points

  1. Food raises blood sugar

    After a meal, sugar from food enters your blood, and blood sugar rises for a while.

  2. Insulin helps sugar into cells

    The pancreas releases insulin. Insulin signals cells, such as muscle cells, to bring more sugar doors to their surface so sugar can move inside.

  3. The two results explain each other

    If cells respond less to insulin, the pancreas can release more to keep blood sugar steady. That’s why an insulin result is read beside glucose.

What to rememberGlucose shows how much sugar is in your blood. Insulin shows how hard your body is working to keep it there. Read together, they tell you more than either one alone.

Sources & references: [6] [7] [8] [9] [10] [11]

What does it measure?

QUICKI stands for Quantitative Insulin Sensitivity Check Index. It combines the logarithms of fasting insulin and fasting glucose into one calculation. The original method was compared with a specialized research measurement of insulin sensitivity, rather than designed as a diagnosis from one routine blood draw. [1]

Before reading the calculation

Inputs
Fasting insulin in µU/mL and fasting glucose in mg/dL, collected together.
Calculation
QUICKI = 1 ÷ [log10(insulin) + log10(glucose)]. Zero or negative inputs cannot be used in these logarithms.
[1]

What can the result mean?

Higher QUICKI values generally indicate greater estimated insulin sensitivity, the opposite direction to HOMA-IR. A lower result may suggest reduced sensitivity in the model. That does not establish diabetes, and insufficient insulin production can complicate interpretation. [1]

Inputs
InsulinSchematic illustration; not to scale. No patient results are shown.
Insulin
Glucose (Fasting)Schematic illustration; not to scale. No patient results are shown.
Glucose (Fasting)

Fasting insulin in µU/mL and fasting glucose in mg/dL, collected together.

Calculation
QUICKI = 1 ÷ [log10(insulin) + log10(glucose)]. Zero or negative inputs cannot be used in these logarithms.
QUICKICalculated result
Calculated resultQUICKI
Read the original measurements alongside the calculation.Schematic illustration; not to scale. No patient results are shown.

When is it useful, and how is it read?

QUICKI belongs to a defined research or specialist question, not a stand-alone diabetes diagnosis. Before comparing results, check that the same formula, required units, and comparable sampling were used. The underlying glucose and insulin still need their own interpretation. [1] [2]

What can affect it?

The original calculation uses glucose in mg/dL and insulin in micro-units per milliliter. Using glucose in mmol/L without the proper conversion changes the answer. The two samples need matching fasting conditions. Medicines, illness, and differences between insulin assays also affect the result. [1] [4]

An interesting fact

Its direction is opposite to HOMA-IR

Higher QUICKI values generally represent greater estimated insulin sensitivity, while higher HOMA-IR values represent more estimated resistance. Their numbers and cutoffs cannot be exchanged, even though both use fasting glucose and insulin. [1] [3]

Questions you might have

Does a higher QUICKI mean more insulin resistance?

In this model, higher values generally reflect greater estimated insulin sensitivity. The direction is opposite to HOMA-IR. [1] [5]

Can I compare QUICKI after changing laboratories?

Check the insulin assay and units first. Differences between laboratories can alter the estimate, even when the formula is the same. [4]

What comes next?

First check the measured glucose and insulin and why the index was requested. Your clinician can decide whether it adds anything to HbA1c, glucose, and the rest of your risk assessment. QUICKI has no universal personal target, and repeating it is useful only when the result can inform a specific decision. [2]

A question to take with you

Were the correct units used, and would QUICKI change my care beyond the underlying results?

The reference interval and units on your report are part of understanding your result. Understand units, reference intervals, and treatment targets.

Sources & references

Medical references & original research

  1. Katz et al. — Quantitative insulin sensitivity check index (original study, 2000)
  2. NIDDK — Insulin resistance and prediabetes
  3. Matthews et al. — Homeostasis model assessment (original study, PubMed, 1985)
  4. Manley et al. — Comparison of 11 Human Insulin Assays (2007)
  5. Hřebíček et al. — QUICKI for epidemiological assessment (2002)
  6. Karnieli E, et al. Insulin stimulates glucose transport in isolated human adipose cells through a translocation of intracellular glucose transporters to the plasma membrane: a preliminary report. Hormone and Metabolic Research. 1986;18:867–868.
  7. Lopez JA, et al. Identification of a distal GLUT4 trafficking event controlled by actin polymerization. Molecular Biology of the Cell. 2009;20:3918–3929.
  8. Kanzaki M. Insulin receptor signals regulating GLUT4 translocation and actin dynamics (review). Endocrine Journal. 2006;53:267–293.
  9. MedlinePlus. Insulin in Blood.
  10. MedlinePlus. Blood Glucose Test.
  11. Cleveland Clinic. Insulin Resistance.

Books we consulted

References that informed our explanations of the test and its context.

  1. Pagana KD, Pagana TJ, Pagana TN. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. Elsevier; 2019.
The atheal team · Content prepared: 2 October 2026

Practical-section sources accessed: .

For general health education. Interpreting your result and deciding on tests or treatment requires your health context and a qualified clinician.

All markers →

Each result adds a different piece. These guides explain the connections; the tests you need depend on your situation.

Blood sugar & insulin FPG

Glucose (Fasting)

Supplies a measured input that must use the formula’s required units.

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Blood sugar & insulin Insulin

Insulin

Supplies the second measured input to the estimate.

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Blood sugar & insulin HOMA-IR

HOMA-IR

Offers a different research estimate with the opposite numerical direction.

Explore this marker