Matsuda Index
The Matsuda index is a measure of whole-body insulin sensitivity calculated from the glucose and insulin readings taken during a two-hour glucose tolerance test, so it shows how well the body responds to insulin after a sugar load.
Plain English
Patient-Friendly Explanation
During a glucose tolerance test a person drinks a sugary solution and has blood taken several times over two hours. The Matsuda index uses those glucose readings together with the matching insulin readings to describe how sensitive the whole body is to insulin - muscle as well as liver. A higher number means the body clears glucose with less insulin, which is better. A lower number means insulin resistance, even when the fasting tests look normal. It is not run in every clinic because it needs repeated blood samples, but it is the most informative way to use a single test.
Medical
Clinical Definition
The Matsuda-DeFronzo index is calculated as 10,000 divided by the square root of the product of the mean glucose and mean insulin concentrations during an oral glucose tolerance test and the corresponding fasting values. It is a composite surrogate for whole-body insulin sensitivity derived from a 75 g oral glucose load sampled fasting and at 30, 60, 90 and 120 minutes, and it incorporates both hepatic and peripheral insulin sensitivity. Correlation with the euglycaemic-hyperinsulinaemic clamp, the reference method, is roughly 0.7 to 0.8, which is better than fasting indices such as HOMA-IR because it captures the post-load response and secretory compensation. Reported cut-points vary with assay and units, commonly around 4 to 5 when glucose is in mg/dL and insulin in micro-units per mL, and each laboratory should be read against its own reference range. Low values predict incident type 2 diabetes, metabolic dysfunction-associated fatty liver disease and cardiovascular events independently of fasting glucose. Limitations: it requires multiple timed samples, is not validated for people already on insulin or with advanced beta cell failure, and cut-points are not standardised across laboratories.
Key Insight
Why It Matters
It is the test that finds insulin resistance in patients whose fasting glucose and HbA1c are still normal, which is exactly the group where an earlier conversation about weight and metabolic risk still changes the trajectory.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: September 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
