Triglyceride/HDL ratio: how it is calculated, table of values and what it means

The triglyceride HDL ratio is not printed on most lipid panels in Mexico, but it can be calculated in ten seconds from two values that almost all of them include: triglycerides and HDL cholesterol. It is a quotient that research has used for twenty years as an indirect marker of insulin resistance and of a smaller, denser type of LDL cholesterol. The first thing to know is that it is a clue, not a diagnosis; the second, that there is no single cut-off, because the thresholds change with the population, with sex and with the units the laboratory uses. This text explains where the number comes from, how to calculate it with five worked examples, which cut-offs research has proposed, including Mexican research, what moves it without your metabolism having changed, and why it is not calculated from a non-fasting sample (on how to prepare, see fasting before a blood test).

What the triglyceride/HDL ratio is and what it tries to measure

Triglycerides are the form in which blood carries fat; HDL cholesterol is the lipoprotein that collects cholesterol from tissues and returns it to the liver, which is why it is called "good".^[9][10] In a person without insulin resistance the two values usually run in opposite directions: moderate triglycerides, high HDL. Insulin resistance breaks that balance in both directions at once. Insulin normally restrains the release of fatty acids from body fat; when cells respond less to it, that release runs "unchecked", the liver receives more fatty acids and makes more triglycerides, which it packs into VLDL particles and sends into the blood.^[5] At the same time the activity of an enzyme that breaks down HDL increases, HDL particles become smaller and less stable, and the production of their main protein, apolipoprotein A-I, falls.^[5]

That is why the ratio makes sense: when triglycerides rise and HDL falls for the same reason, dividing one by the other amplifies the signal. The group of Gerald Reaven at Stanford tested it in 2003 in 258 overweight adults without diabetes, measuring insulin resistance with the reference method (the insulin suppression test) and comparing it with the markers any laboratory reports. A triglyceride cut-off of 130 mg/dL identified insulin-resistant people with 67 % sensitivity and 71 % specificity; a TG/HDL ratio of 3.0, with 64 % and 68 %; fasting insulin was more specific (85 %) but less sensitive (57 %).^[1] Their conclusion was pragmatic: without a standardized insulin assay, triglycerides or the TG/HDL ratio were the most practical way to identify who was insulin resistant.^[1]

Two years later the same group expanded the sample to 449 apparently healthy adults for insulin resistance and 1135 for LDL particle size. Of all the routine measurements, the triglyceride/HDL ratio was "the best predictor" of both insulin resistance and LDL diameter, with an optimal cut-off of 3.5; and sensitivity and specificity were "even greater" for identifying those with small, dense LDL.^[2] That is the second reason the ratio matters: small, dense LDL is the form of cholesterol a recent Mexican paper calls "the most concerning aspect" of atherogenic dyslipidemia, and the ratio detects it better than total LDL does.^[4] If your LDL came back high, the context is in high cholesterol: what it means and what to do.

How it is calculated: the formula and five worked examples

The formula is a direct division: TG/HDL ratio = triglycerides (mg/dL) / HDL cholesterol (mg/dL). Both values must come from the same lipid panel, taken fasting, and be in the same units. In Mexico laboratories report in mg/dL, and every cut-off on this page is in those units.^[1][3] An example with the numbers people search for most: triglycerides of 155 and HDL of 45. Divide 155 by 45 and you get 3.44. The table gathers five cases so you can place yours:

Two details from the table. First: with triglycerides of 155, a man with HDL of 45 is within the healthy range and a woman is below her threshold of 50, even though the ratio is identical; that is why sex-specific cut-offs exist.^[10] Second: when triglycerides go above 400 or 500, the ratio stops being useful, because any HDL gives a huge quotient and the question changes to why triglycerides are so high.^[6][9] We wrote about that in high triglycerides: what it means and what to check.

If your laboratory reports in mmol/L

Outside Mexico many laboratories report lipids in mmol/L, and there the ratio changes its number even though the blood is the same, because triglycerides and cholesterol convert with different factors. The European lipid consensus equates 1.7 mmol/L of triglycerides with 150 mg/dL, and 1.0 mmol/L of HDL with 40 mg/dL.^[6] If you divide in mg/dL, 150 by 40 gives 3.75; if you divide the same values in mmol/L, 1.7 by 1.0 gives 1.7. The result in mmol/L comes out more than two times smaller, so a cut-off of 3.0 or 3.5 designed in mg/dL cannot be applied to a result in mmol/L without first converting each value. If you have results of both kinds, convert them all to mg/dL before comparing, and remember that the printed reference range is not your personal norm.

What does a TG/HDL ratio of 2, 3.5 or 5 mean?

A ratio of 2 is below every cut-off proposed for adults, including the lowest ones suggested for women; a ratio of 3.5 matches the optimal cut-off of the 2005 Stanford study and practically the 3.46 proposed for Mexican adults against metabolic syndrome; and a ratio of 5 exceeds every cut-off and falls in the intermediate band of the quartiles measured in Mexico City.^[2][3][4][5] That is the short answer. The long one is that each cut-off comes from a different population, method and question, and it is worth knowing where each number comes from before applying it to your result:

Look at the third row. In the same Mexican population the cut-off is 3.46 if the question is "which value best separates those who already meet metabolic syndrome criteria" and 3.0 if the question is "which value lets fewer cases slip through", at the cost of more false positives; that is why the authors propose 3.0 for screening and not for confirmation.^[3] In that study, people without metabolic syndrome had an average ratio of 2.9 (median 2.3) and those with it, 6.6 (median 5.2): the distance between the two groups is large, but the ranges overlap, and that is where the ratios of 3 to 4 that generate most doubts live.^[3]

Practical reading: between 2 and 3 the cut-offs proposed for women and for some populations begin, and context decides; between 3 and 3.5 you cross the cut-offs of the original studies and of the Mexican one; above 4.6 you are in the upper half of what was measured in Mexico City.^{[1][2][3][4][5]} None of this is a diagnosis: the ratio points to a pattern that the doctor confirms or rules out with waist, blood pressure, glucose and, if needed, insulin.

Why cut-offs depend on population, sex and units

Women before menopause tend to have lower triglycerides and higher HDL than men, so the same degree of insulin resistance produces a smaller ratio in them; that is why almost every study that separates by sex finds lower cut-offs in women, and the 2024 review also notes that the ratio is more accurate in men than in women.^[5] The HDL threshold the guidelines use reflects the same thing: below 40 mg/dL is low in men and below 50 in women.^[7][10] In the Mexico City cohort the median was 2.84 in women and 3.24 in men, and the mean 3.63 and 4.62.^[4]

Ancestry matters too. The review of 17 studies finds that the ratio "demonstrates greater accuracy" in people of European, Asian and Hispanic background than in African American populations, where the proposed cut-offs drop to 1.5 in women and 2 in men.^[5] For the Mexican population there are at least two studies of its own: the one of 1318 adults from the center of the country, with the 3.46 cut-off, and the cohort of 68,000 people from Mexico City, whose authors warn that the ratio "varies significantly across ethnicities and clinical conditions" and propose reading it by quartiles of the population itself.^[3][4] And one general limit: in most studies the ability of the ratio to classify people correctly (the area under the curve) "virtually never surpasses" 0.8, that is, it gets most cases right and a non-trivial minority wrong.^[5]

The Mexican context explains why the ratio draws so much interest here. According to the national ENSANUT 2020 survey cited in the Mexico City paper, 48.9 % of adults had hypertriglyceridemia and 28.3 % had HDL below 40 mg/dL (21.6 % of women and 35.5 % of men).^[4] The Mexican Official Standard on dyslipidemias defines hypertriglyceridemia as triglycerides above 150 mg/dL and hypoalphalipoproteinemia as HDL below 40.^[8]

What moves the ratio without changing your metabolism

The ratio divides the value in the lipid panel that moves most from one day to the next, triglycerides, by one of the most stable, HDL. Any deviation in triglycerides passes straight into the ratio. This is what most often distorts an isolated result:

• Incomplete fast. The Mexican Official Standard requires 9 to 12 hours of fasting to measure triglycerides, although total cholesterol and HDL can be measured without fasting.^[8] The European consensus measured how much triglycerides rise after a habitual meal: on average up to 0.3 mmol/L, about 26 mg/dL, 1 to 6 hours later; little for someone with triglycerides of 90, enough to cross a cut-off if you are at 140.^[6] With triglycerides of 155 and HDL of 45, those 26 mg/dL move the ratio from 3.44 to 2.87 or to 4.02 depending on which side they fall.
• Heavy dinner or alcohol the night before. Excessive alcohol and a diet high in fat and sugar are among the causes of high triglycerides the NIH list, and sustained alcohol also lowers HDL indirectly through weight.^[9][10] A single unusual night does not change your metabolism, but it does change the next morning sample.
• Illness, thyroid, liver and kidney. Kidney, liver and thyroid disease, poorly controlled diabetes and overweight are on the list of conditions that raise triglycerides.^[9] A cold the week before is not on the guideline lists, but the general principle of repeating under stable conditions before concluding is.
• Medicines. Some diuretics and certain treatments for high blood pressure, breast cancer and HIV raise triglycerides; beta blockers, anabolic steroids, the progestins in some contraceptives and menopause therapies, and benzodiazepines lower HDL.^[9][10] A new medicine between two panels can explain the whole change in the ratio. Do not stop anything on your own: write it down and discuss it.
• Very high triglycerides. If a non-fasting sample comes back with triglycerides above 440 mg/dL, the European consensus recommends repeating it fasting; and above 400, the usual formula for calculating LDL is no longer valid, so the whole panel is recalculated.^[6]

What to do with the result and when to repeat it

• Ratio below 2 with triglycerides below 150 and HDL above 40 or 50. Save it with its date as a baseline. The Mexican Official Standard indicates repeating the lipid panel every 5 years from age 20 if there are no risk factors, and every 1 to 2 years if there are; MedlinePlus agrees and adds that men aged 45 to 65 and women aged 55 to 65 are checked every 1 to 2 years.^[8][10] What else to include in that check-up is in annual preventive check-up.
• Ratio between 2 and 3.5 with a single value out of place. Look at each value separately: high triglycerides with normal HDL have different causes than low HDL with normal triglycerides. Note alcohol, sugar, medicines and smoking, and repeat in 2 to 3 months at the same laboratory after 9 to 12 hours of fasting.^[8][9][10]
• Ratio above 3.5 with triglycerides of 150 or more and low HDL. Add what is missing so the pattern has context: waist, home blood pressure for seven days, fasting glucose and HbA1c. Triglycerides of 150 or more, HDL below 40 or 50, blood pressure of 130/85 or more, fasting glucose of 100 or more and a grown waist are the five criteria of metabolic syndrome; three of five make the diagnosis, and the doctor decides that.^[3][7] Book an appointment in the coming weeks. If the reason for looking at the ratio was that you are not losing weight or that you get sleepy after meals, bring that too: the ratio does not explain the symptom on its own, but it organizes the conversation.
• Triglycerides persistently at 175 or more. The AHA/ACC cholesterol guideline considers them a risk-enhancing factor regardless of the ratio, and takes them into account when deciding together with LDL and overall risk.^[7] It is a piece of data for the appointment, not for the calculator.
• What the guidelines associate with lower triglycerides and higher HDL. The NIH list heart-healthy eating, regular physical activity, a healthy weight, quitting smoking, good sleep and limiting alcohol; MedlinePlus adds that losing weight, especially around the waist, and 30 minutes of aerobic exercise most days raise HDL.^[9][10] What to change and by how much is decided with the doctor, with your data in front of you.
• When to repeat. There is no fixed frequency for the ratio itself. What helps is repeating the full panel under the same conditions and at the same laboratory, months apart, to see the direction of change in triglycerides and HDL separately and not the noise of one morning.^[6][8]

Warning signs

High triglycerides and low HDL cause no symptoms: the NIH say it plainly, they "usually do not cause any symptoms".^[9] What does require not waiting for the next check-up is the absolute triglyceride value when it shoots up, because the risk stops being the heart in the long term and becomes the pancreas in the short term.

• Triglycerides of 500 mg/dL or more. The guidelines call them "very high"; at that level they can cause acute pancreatitis, changes in the blood vessels of the retina and skin lesions on the back, chest, arms and legs.^[9] The European consensus sets the referral threshold for pancreatitis risk at triglycerides above 880 mg/dL, and the Mexican Official Standard notes that above 1000 mg/dL the pancreatitis risk is short-term.^[6][8] With any of these values, book an appointment in the coming days, not at the next check-up; with 1000 or more, today.
• Severe pain in the upper abdomen, often with nausea or vomiting, in a person with very high triglycerides is how pancreatitis presents: emergency. The NIH also describe that with triglycerides above 1500 mg/dL there can be stomach pain, enlargement of the liver and spleen and short-term memory loss.^[9]
• Skin lesions (yellowish bumps or plaques on the back, chest, arms, legs or eyelids) accompanying very high triglycerides are the fat deposits the NIH describe as skin damage from very high levels; a reason for a prompt appointment.^[9]
• Very high triglycerides in a young person, or a close relative with very high triglycerides or pancreatitis, point to an inherited disorder of lipid metabolism, and the NIH indicate that in that case genetic testing and checking the family may be needed.^[9] The Mexican Official Standard defines familial hypertriglyceridemia from triglycerides above 200 mg/dL with family history, and the AHA/ACC guideline calls for a fasting panel from the first evaluation when there is a family history of premature cardiovascular disease or genetic hyperlipidemia.^[7][8]

What to bring to the doctor

An appointment for a high TG/HDL ratio lasts as long as it takes to explain the context. If you arrive with the context in order, the conversation starts where it should: on whether the pattern is real and what else needs measuring.

1. The complete lipid panel, with triglycerides, HDL, LDL and total cholesterol in their units, date and laboratory. If you have more than one, bring them all: the direction of change says more than the ratio of one morning.^[6]
2. The conditions of the sample: hours of fasting, what you had for dinner and whether there was alcohol the night before, time of the draw, whether you were ill.^[6][8]
3. Recent waist and weight, and whether you have noticed your waist growing: it is the metabolic syndrome criterion measured at home.^[3][7]
4. Home blood pressure: the seven-day average with an upper-arm device, if you have one.^[7] How to take it is in normal blood pressure.
5. Fasting glucose and HbA1c, with dates, if you have them; if not, bring them as a question, as with fasting insulin.^[3][7] The detail on glucose is in high fasting glucose.
6. History: relatives with a heart attack or stroke at an early age, very high triglycerides or pancreatitis; diabetes in the family.^[7][9]
7. List of medicines and supplements, including diuretics, beta blockers, oral contraceptives, corticosteroids and anabolic steroids, and whether you smoke.^[9][10]
8. Three questions: whether the pattern justifies measuring fasting insulin or HbA1c, which cut-off your doctor uses to interpret the ratio and for which population, and how often to repeat the panel in your case.