QUICKI Calculator

What is QUICKI?

The Quantitative Insulin Sensitivity Check Index (QUICKI) is a mathematical index that estimates how sensitive the body is to insulin using just two routine fasting blood values: fasting serum insulin and fasting plasma glucose. It was developed by Katz and colleagues and published in the Journal of Clinical Endocrinology and Metabolism in 2000. Unlike the gold-standard hyperinsulinemic-euglycemic clamp, which requires continuous intravenous glucose and insulin infusions over several hours, QUICKI can be derived from a single blood draw. In the original validation study, QUICKI correlated strongly with clamp-measured glucose uptake (r = 0.78), making it a practical surrogate for clinical and research settings.

How the QUICKI formula works

The formula is QUICKI = 1 divided by the sum of the base-10 logarithms of fasting insulin (in uU/mL) and fasting glucose (in mg/dL). Taking logarithms before summing compresses the wide biological range of these values and makes the index roughly linear with clamp-measured insulin sensitivity - a key advantage over HOMA-IR, which uses the raw product of the two values and is therefore non-linear across the full range. The reciprocal (1 divided by the sum) means that higher insulin or higher glucose - both signs of resistance - produce a smaller QUICKI, while good sensitivity gives a larger number, typically around 0.38 or above in healthy adults. Glucose must be in mg/dL for the standard formula; if your lab reports in mmol/L, multiply by 18.0182 before applying the logarithm. This calculator handles that conversion automatically when you select mmol/L.

Interpreting your QUICKI score

There is no single universally agreed cutoff, so the useful approach is to compare your number with published group means. In the original Katz et al. cohort the mean QUICKI was 0.382 in healthy non-obese subjects, 0.331 in obese subjects and 0.304 in subjects with type 2 diabetes. Hrebicek et al. (2002) measured a mean of 0.366 in 259 healthy adults and found that 0.357, the lower 95% limit of that healthy group, separated people with metabolic-syndrome features from those without. A 2016 population study of 5,511 adults by Motamed et al. put the optimal metabolic-syndrome cut points at 0.343 for men and 0.331 for women. Read together, a result above roughly 0.36 is unremarkable, the mid-0.33s are the zone where metabolic risk clusters begin to appear, and values near or below 0.304 are typical of established type 2 diabetes in research cohorts. Note that a much-repeated claim that "normal" QUICKI is above 0.45 does not come from any of these studies: 0.45 would require a fasting insulin near 2 uU/mL, which is far below the level of a typical healthy adult. Because population norms and insulin assays vary between laboratories, your result should always be interpreted by a clinician who knows your full clinical picture.

QUICKI versus HOMA-IR

HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) is the other widely used fasting-only index. It equals fasting insulin times fasting glucose in mmol/L, divided by 22.5. A higher HOMA-IR means more resistance, which is the opposite direction from QUICKI. In validation studies, QUICKI showed a slightly more linear relationship with clamp-measured insulin sensitivity than HOMA-IR, particularly at the extremes of the sensitivity range. Practically, both indices use the same two inputs, so they carry the same information - the choice between them is mostly a matter of convention in a given clinical or research setting. This calculator displays both side by side so you can cross-reference whichever threshold your clinician or protocol uses.