Triglyceride-glucose product — a proxy for insulin resistance.
What does the TyG index mean?
The Triglyceride-Glucose (TyG) index is a simple mathematical proxy for insulin resistance that can be derived from a standard fasting lipid panel and glucose test, without needing to measure fasting insulin. It was proposed by Guerrero-Romero and colleagues in 2010 as an alternative to HOMA-IR for settings where insulin measurement is not available or affordable.
The formula is: TyG = ln(triglycerides mg/dL × fasting glucose mg/dL ÷ 2). Both components of the TyG index are elevated in insulin-resistant states. Elevated triglycerides reflect impaired insulin-stimulated suppression of lipolysis and increased hepatic VLDL secretion. Elevated fasting glucose reflects impaired insulin-mediated glucose uptake. Their product, transformed logarithmically, produces a continuously distributed index that correlates well with more invasive measures of insulin resistance.
Multiple validation studies have compared TyG against the euglycaemic-hyperinsulinaemic clamp (the gold standard) and consistently found good correlations. TyG has also been shown to predict incident type 2 diabetes, metabolic syndrome, non-alcoholic fatty liver disease, and cardiovascular events in large prospective cohort studies.
Compared to HOMA-IR, TyG may better reflect peripheral (muscle) insulin resistance because triglycerides more directly index triglyceride-rich lipoprotein clearance. The two markers are complementary rather than redundant.
Reference ranges
| TyG Index | Interpretation |
|---|---|
| < 8.0 | Low insulin resistance risk |
| 8.0 – 8.5 | Borderline / moderate risk |
| > 8.5 | Elevated insulin resistance; metabolic syndrome risk |
When should you see a doctor?
A TyG above 8.5, especially combined with abdominal obesity, elevated blood pressure, or a history of gestational diabetes or PCOS, suggests metabolic syndrome and insulin resistance that warrants clinical evaluation. Your doctor may recommend further metabolic testing, lifestyle modification guidance, or pharmacological intervention depending on your full clinical picture.
Frequently asked questions
What is the TyG index and what does it measure?
The triglyceride-glucose (TyG) index is calculated as ln(triglycerides mg/dL × fasting glucose mg/dL / 2). Both elevated triglycerides and elevated fasting glucose are individually associated with insulin resistance, and their product amplifies the signal. Studies validate TyG as a simple surrogate for insulin resistance that can be calculated from a standard lipid and glucose panel without requiring fasting insulin.
How does TyG compare to HOMA-IR?
TyG and HOMA-IR are both surrogate markers of insulin resistance, but they capture different aspects. HOMA-IR uses insulin directly and primarily reflects hepatic insulin resistance. TyG uses triglycerides and glucose without requiring insulin measurement, making it cheaper and more widely available. Multiple studies show TyG correlates well with the gold-standard euglycaemic clamp and may better predict cardiovascular outcomes and metabolic syndrome progression in some populations.
What TyG index indicates insulin resistance?
A TyG index above 8.5 is commonly used as a cut-point for insulin resistance in research literature. Some studies use 4.68 (calculated differently in SI units). The optimal threshold varies by population, sex, and ethnic group. Higher values are consistently associated with greater risk of metabolic syndrome, type 2 diabetes, and cardiovascular events.