If you have had a cholesterol test, you already own the single most useful number in preventive cardiology. You just have to calculate it yourself: triglycerides divided by HDL cholesterol. As a cardiologist, I check the triglyceride HDL ratio before I look at LDL, and in this article I will explain why, how to interpret it, and why it responds to lifestyle far faster than LDL ever does.
Why LDL cholesterol tells an incomplete story
The LDL value on a standard panel is a measurement of cholesterol mass — the amount of cholesterol packed inside LDL particles. It does not tell you how many particles are circulating or how large they are. That distinction is not academic. Small, dense LDL particles penetrate the arterial wall more easily and are far more prone to oxidation, and oxidized LDL is the trigger for the immune response that builds plaque. Large, buoyant LDL particles resist oxidation and are comparatively benign.
Two people can have the same LDL of 150 mg/dL with entirely different particle profiles — one carrying a swarm of small, dense, oxidation-prone particles and the other carrying fewer, larger, harmless ones. A standard panel cannot distinguish them. The triglyceride HDL ratio usually can. (I wrote about the related particle-number problem in ApoB vs LDL cholesterol.)
What the ratio actually measures
Elevated triglycerides paired with low HDL is the classic lipid signature of insulin resistance, and it travels with small, dense LDL almost every time. Low triglycerides with high HDL signals the opposite: large, buoyant particles and healthy insulin sensitivity. Because the ratio captures both variables at once, it serves as a practical surrogate for LDL particle size and for the metabolic state producing it — without the cost of an NMR particle test or an ApoB measurement.
That is also why the ratio functions as an early-warning system for insulin resistance. Insulin resistance drives the liver to release triglyceride-rich particles and suppresses HDL years before fasting glucose or hemoglobin A1c cross an abnormal threshold. Stanford researchers led by Tracey McLaughlin showed in the Annals of Internal Medicine in 2003 that a ratio of 3.0 or higher (using the mg/dL units American labs report) identifies insulin resistance in overweight adults with reasonable accuracy, and later work has repeatedly confirmed the ratio as one of the best simple markers available.
The study that convinced me
In 1997, J. Michael Gaziano and colleagues published a case-control study in Circulation comparing 340 patients who had suffered a first heart attack with 340 age- and sex-matched controls from the Boston area. Triglycerides alone were associated with risk. HDL alone was associated with risk. But the ratio of the two was in a different league: people in the highest quartile of the triglyceride HDL ratio had roughly sixteen times the risk of a first heart attack compared with those in the lowest quartile. Few markers in cardiology separate risk that sharply, and this one costs nothing.
How to calculate and read your ratio
Find triglycerides and HDL on your last lipid panel and divide. A triglyceride level of 230 with an HDL of 39 gives a ratio of about 5.9. A triglyceride level of 60 with an HDL of 75 gives a ratio of 0.8.
One caveat before the numbers: normal is not the same as optimal. Reference ranges are drawn from a population in which insulin resistance is now the majority condition, so a ratio most labs would consider unremarkable can still be far from healthy.
Here is how I interpret the result in my own practice:
- Below 1.8 to 1: optimal. This pattern usually means large, buoyant LDL and good insulin sensitivity, and I weigh it more heavily than a “normal” LDL.
- 3 or above: I assume insulin resistance is present until proven otherwise, and I look further — fasting insulin, waist circumference, liver enzymes, blood pressure.
- 4 or above: high-risk territory in my view, regardless of how reassuring the LDL number appears.
(If your lab reports in mmol/L, multiply the ratio by roughly 2.3 to compare with these mg/dL thresholds.)
Why the ratio moves when LDL won’t
LDL cholesterol is notoriously resistant to lifestyle change; that stubbornness is a large part of why statins became the default. The triglyceride HDL ratio behaves differently, because it reflects insulin resistance — and insulin resistance is among the most reversible conditions in medicine. Reducing refined carbohydrates and sugar, eating protein and fiber before starchy foods, walking for ten minutes after meals, building muscle with resistance training, and restoring sleep all lower triglycerides and raise HDL within weeks. Statins, by contrast, barely alter the ratio. I have watched patients cut the ratio in half in a matter of months without a single new prescription.
The 82-year-old man with persistent atrial fibrillation whose case I described recently on this site shows why the calculation has to be done by hand. In the two years before our first visit his ratio had drifted upward from 1.6 to 2.6, and his initial panel with me read triglycerides 93 mg/dL and HDL 36 mg/dL with nothing flagged: triglycerides fell in the “in control” range and HDL was labeled merely “moderate.” That laboratory had calculated a total-cholesterol-to-HDL ratio for him, but not the triglyceride HDL ratio. An NMR particle test along the way had already shown what a rising ratio predicts — an elevated count of small, dense LDL particles. By every marker on the page he was normal. He was not optimal, and insulin resistance became one of the root causes his program targeted — because the terrain that sustains an arrhythmia and the terrain that produces small, dense LDL are, to a large degree, the same terrain.
The bottom line
LDL is the number we are trained to treat. The triglyceride HDL ratio is the number that explains why the LDL is there and what it is made of. Calculate yours today. If it is above 3, the most important next step is not a prescription; it is finding and reversing the insulin resistance producing that pattern — and, as I argued in why I never use synthetic vitamins, doing it with real food rather than isolated pills.
If you would like a second opinion on your own lipid panel and what it is really telling you, that is exactly what my telehealth second-opinion consults are for. More of my writing lives at andrewrudinmd.com.
Sources
- Gaziano JM, Hennekens CH, O’Donnell CJ, Breslow JL, Buring JE. Fasting triglycerides, high-density lipoprotein, and risk of myocardial infarction. Circulation. 1997;96(8):2520–2525.
- McLaughlin T, Abbasi F, Cheal K, Chu J, Lamendola C, Reaven G. Use of metabolic markers to identify overweight individuals who are insulin resistant. Annals of Internal Medicine. 2003;139(10):802–809.