TyG Index (Triglyceride-Glucose Index)

What is TyG Index (Triglyceride-Glucose Index)?

The TyG index is a calculated value combining fasting triglycerides and fasting glucose, used in research as a low-cost stand-in for insulin resistance testing.

Mexican researchers Luis Simental-Mendía, Martha Rodríguez-Morán, and Fernando Guerrero-Romero introduced the TyG index in 2008 as a cheaper alternative to insulin-based tests for insulin resistance. The formula is the natural log of fasting triglycerides in mg/dL multiplied by fasting glucose in mg/dL, with that product logged, then divided by 2: TyG = ln(triglycerides × glucose) / 2. That division placement matters more than it sounds. An early misprint had some researchers dividing by 2 inside the brackets rather than after the log, which changes the result. The original authors published a 2023 correction confirming that dividing after the log, not before, is the version their own validation data actually used. Triglycerides and glucose are both part of a standard fasting lipid and metabolic panel, the kind ordered at most annual physicals. That's TyG's practical advantage over other insulin-resistance surrogates: no extra blood draw and no specialized assay, just two numbers already on a routine lab report. Longetic doesn't run this calculation. It keeps the triglyceride and glucose values from your uploaded reports organized side by side, so the numbers are there if you or your doctor want to work through them.

Typical reference context

Published TyG cutoffs vary by population and by what they're validated against, so there's no single clinical threshold. Two recent examples:

A published cutoff describes where one study drew its line for its own purposes, not a verdict on any individual's result.

What changed recently

A 2025 comparison in *Diabetes Research and Clinical Practice* found that TyG index and HOMA-IR aren't interchangeable. TyG tracked more closely with cardiovascular risk markers in that cohort; HOMA-IR did not. HOMA-IR, meanwhile, tracked more closely with diet quality, including fiber intake and Mediterranean-diet adherence, and with the inflammatory marker IL-18.

A 2026 cross-sectional study from Gujarat, India, found TyG outperformed HOMA-IR for identifying metabolic syndrome, with an area under the curve of 0.85 versus 0.81 for HOMA-IR. Separately, a 2024 diagnostic study found that combined indices folding in body size, TyG-BMI and TyG-waist circumference, detected liver fat more accurately than TyG alone (area under the curve 0.82 and 0.81, versus 0.72 for TyG by itself), suggesting body measurements capture something TyG's two lab values miss alone.

Tests often checked alongside this

• Fasting insulin — the draw HOMA-IR needs, a specialized assay that isn't standardized across labs the way glucose and triglyceride tests are. TyG skips it entirely.
• HbA1c — shows average blood sugar over roughly three months, a different timescale than the single fasting snapshot TyG uses.
• Lipid panel (LDL, HDL, total cholesterol) — triglycerides are already one line on this panel.
• Fasting glucose or an oral glucose tolerance test — glucose is one of TyG's two inputs, but on its own it flags a different category (impaired fasting glucose) than TyG's insulin-resistance framing.
• Waist circumference or BMI — recent research recombines TyG with body measurements, and some studies found those combined versions more accurate than TyG alone.

What can affect this marker

• A meal or snack inside the fasting window: even a few hours' departure from an 8-to-12-hour fast raises both triglycerides and glucose on its own.
• Alcohol in the prior 24 hours: the liver converts alcohol into triglyceride precursors, so recent drinking can raise the triglyceride half of the equation.
• Untreated hypothyroidism: low thyroid hormone slows how fast the body clears triglycerides from blood.
• Certain medications: beta-blockers, some diuretics, corticosteroids, and retinoids can each raise triglycerides or glucose as a side effect.
• Acute illness or infection: the stress response raises cortisol and adrenaline, which raise blood glucose temporarily.

What to track over time

• Your fasting triglyceride and glucose values from each new report, side by side.
• The reference range each lab printed for triglycerides and glucose.
• Whether each triglyceride test was actually done fasting.
• Any related results ordered around the same time, such as HbA1c or a full lipid panel.

What to ask your doctor

• Was this triglyceride and glucose test done fasting, and does that match how my earlier results were measured?
• Does my triglyceride or glucose number on its own need any follow-up testing?
• If insulin resistance is a concern for me, would a fasting insulin test, an oral glucose tolerance test, or something else tell you more than a calculated index would?
• Could any of my current medications be raising my triglycerides or glucose?
• How does my latest fasting triglyceride and glucose compare with my previous results?

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