Insulin Sensitivity QUICKI Calculator

Insulin Sensitivity QUICKI Calculator for Endocrinology. QUICKI has no universal diagnostic cutoff; interpret it against population reference bands. Approximate mean values from the original validation are about 0.382 in lean healthy adults, 0.331 in obese non-diabetic adults, and 0.304 in type 2 diabetes, so lower numbers mean worse sensitivity. Values around 0.34 and above generally reflect preserved sensitivity, roughly 0.30-0.34 suggests reduced sensitivity, and below 0.30 indicates marked resistance. Because the numeric spread is narrow, small differences matter and the index is best used with an assay-specific local reference range and for tracking within-patient change rather than as a hard binary threshold.

How this calculator works

QUICKI (Quantitative Insulin Sensitivity Check Index) is derived from a single fasting blood draw: 1 / [log10(fasting insulin in uU/mL) + log10(fasting glucose in mg/dL)]. The double log transformation compresses the skewed distributions of fasting insulin and glucose and linearizes the relationship with clamp-derived insulin sensitivity far better than the untransformed fasting insulin-glucose product used by HOMA-IR. Higher QUICKI values indicate greater insulin sensitivity; lower values indicate resistance. Glucose entered in mmol/L must first be converted to mg/dL (multiply by 18.0182).

When to use this calculator

Use QUICKI as a simple, reproducible surrogate for insulin sensitivity in epidemiologic studies, large-cohort screening, and serial monitoring where the hyperinsulinemic-euglycemic clamp is impractical. It performs well across lean, obese, and type 2 diabetic adults and correlates tightly with clamp glucose disposal (r roughly 0.7-0.8). Do not use it to diagnose diabetes, and avoid it in patients on exogenous insulin, in fulminant beta-cell failure with very low endogenous insulin, or when a validated fasting insulin assay is unavailable, because the index becomes uninterpretable when fasting insulin no longer reflects intrinsic secretion.

Inputs used

  • Fasting insulin
  • Fasting glucose

Clinical interpretation

QUICKI has no universal diagnostic cutoff; interpret it against population reference bands. Approximate mean values from the original validation are about 0.382 in lean healthy adults, 0.331 in obese non-diabetic adults, and 0.304 in type 2 diabetes, so lower numbers mean worse sensitivity. Values around 0.34 and above generally reflect preserved sensitivity, roughly 0.30-0.34 suggests reduced sensitivity, and below 0.30 indicates marked resistance. Because the numeric spread is narrow, small differences matter and the index is best used with an assay-specific local reference range and for tracking within-patient change rather than as a hard binary threshold.

Worked example

A patient has fasting insulin 12 uU/mL and fasting glucose 100 mg/dL. log10(12) = 1.079 and log10(100) = 2.000, summing to 3.079. QUICKI = 1/3.079 = 0.325. This falls in the mildly insulin-resistant range (below the ~0.34 threshold typical of lean healthy adults but above the ~0.30 seen in overt type 2 diabetes), consistent with early metabolic syndrome and prompting lifestyle intervention and cardiometabolic risk assessment.

Limitations and safety notes

QUICKI depends entirely on the fasting insulin assay, which is not standardized across platforms, so absolute values are not portable between labs and cohorts. It reflects predominantly hepatic (fasting) insulin action and does not capture postprandial or peripheral muscle sensitivity, and it becomes meaningless when endogenous insulin is absent or replaced by therapy (advanced beta-cell failure, exogenous insulin, insulin secretagogues). It also loses reliability in pregnancy, and its narrow dynamic range makes it sensitive to assay imprecision and to any non-fasting sample.

Frequently asked questions

How does QUICKI differ from HOMA-IR?

Both use only fasting glucose and insulin, but QUICKI applies a double log10 transformation that linearizes the relationship with clamp-measured sensitivity, giving tighter correlations, especially in obese and diabetic patients. QUICKI rises with sensitivity while HOMA-IR rises with resistance, so they move in opposite directions. In practice they rank patients very similarly.

What units must I use?

Fasting insulin in microunits per milliliter (uU/mL, equivalent to mIU/L) and fasting glucose in mg/dL. If your glucose is reported in mmol/L, multiply by 18.0182 before entering it. Using SI insulin units (pmol/L) without conversion will produce an incorrect index.

Is there a single cutoff for insulin resistance?

No. QUICKI is a continuous index with a narrow range and no consensus diagnostic threshold. Interpret it against a local, assay-specific reference range, using population means (roughly 0.38 lean, 0.33 obese, 0.30 type 2 diabetes) as orientation rather than fixed rules.

Can I use QUICKI in patients on insulin?

No. The index assumes fasting insulin reflects endogenous secretion. Exogenous insulin, sulfonylureas, or advanced beta-cell failure break that assumption and make the result uninterpretable.

References

  • Katz A, Nambi SS, Mather K, Baron AD, Follmann DA, Sullivan G, Quon MJ. Quantitative insulin sensitivity check index: a simple, accurate method for assessing insulin sensitivity in humans. J Clin Endocrinol Metab. 2000. PMID: 10902785.
  • Chen H, Sullivan G, Quon MJ. Assessing the predictive accuracy of QUICKI as a surrogate index for insulin sensitivity using a calibration model. Diabetes. 2005. PMID: 15983190.

Editorial review and citation methodology

Reviewed by the Quick Medical Calculator Editorial Team. Last reviewed: May 27, 2026. The review checks calculator inputs, intended population, interpretation, limitations, and source alignment.

  • Prefer original validation studies for scoring systems and prediction tools.
  • Use current specialty society guidance, transplant allocation policy, public health guidance, or regulator resources when they govern clinical use.
  • Include limitations and safety notes when a calculator is population-specific, context-dependent, or unsuitable as a standalone decision tool.

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