The Overlooked Link Between Low Testosterone & Heart Disease

In my practice, I regularly see a version of the same patient — a man in his early 50s who had the kind of cardiac workup his primary care doctor called reassuring: cholesterol and blood pressure within the traditionally acceptable ranges, no family history of heart disease. One of the first things I do is run a more comprehensive panel, including a marker most physicians don’t associate with heart health: testosterone.

Low testosterone is both a warning sign of poor heart health, and a contributor to it. Men with the lowest testosterone levels have a 40–50% higher risk of heart failure than those with healthier levels.¹ But even milder, age-related declines in testosterone levels can increase heart disease risk.² 

Why Testosterone Matters for Heart Health

Testosterone helps regulate the systems that keep your heart healthy — how your body handles blood sugar, how your arteries function, and how much fat accumulates around your organs. When testosterone levels drop, those systems drift in the wrong direction at the same time, compounding risk. The damage can begin long before symptoms show up or standard cholesterol tests indicate a problem.

Major organizations consider a normal testosterone range, which represents the middle 95% of healthy individuals but doesn’t necessarily reflect levels associated with longevity, to be 450–600 ng/dL (nanograms per deciliter).³ Optimal testosterone ranges, which are based on clinical guidelines, peer-reviewed research, and real-world outcomes data, and which emphasize levels associated with peak functioning and reduced disease risk, may be 700–1200 ng/dL.⁴ At healthy levels, testosterone may be protective:

• Keeps blood vessels flexible and open for blood flow
• Maintains muscle mass and regulates blood sugar
• Keeps cholesterol in a healthy range
• Tamps down inflammation

But one in three men between the ages of 40 and 80 have low testosterone.^{5 6} At levels below 300 ng/dL, those protections erode and are linked to a range of heart problems that can cascade into general health dysfunction.⁷ Men with chronic heart failure and low testosterone have measurably higher rates of death from any cause.⁸

Testosterone helps protect blood vessel function

Testosterone plays a role in the production of nitric oxide, a compound that keeps blood vessels flexible and less likely to stiffen or narrow over time. Testosterone also helps dilate your blood vessels when the heart needs more blood, like during exercise or in times of stress, lessening the strain on your heart.

When nitric oxide production declines, arteries stiffen and blood flow is reduced. Stiffer arteries force the heart to work harder, raising blood pressure over time. Reduced blood flow starves the heart of oxygen, and when a plaque deposit in an artery wall breaks open, the body responds by forming a clot. If that clot blocks the artery, the result is a heart attack.⁹

Low testosterone fuels chronic inflammation

Low testosterone promotes visceral fat, the deep abdominal fat that generates chronic inflammation. Inflammation can cause heart problems because it damages blood vessels over time and makes them more vulnerable to the buildup of unstable plaque that can rupture and trigger a heart attack. ^{10 11 12 13 14}

Think of heart disease as a fire. Cholesterol is the fuel — it’s present in everyone’s blood, and in isolation it isn’t necessarily dangerous. Inflammation is what lights the match. When the inflammatory burden is high enough, it activates cholesterol particles, drives them into the artery lining, and triggers the plaque buildup that can eventually rupture and cut off blood flow to the heart.

Low testosterone turns up the heat. Men with low testosterone show:

• Higher levels of C-reactive protein (CRP), a marker of inflammation.¹⁵ Higher CRP is a strong predictor of heart attack and stroke, even when LDL cholesterol is in the normal range.¹⁶
• A high neutrophil-to-lymphocyte ratio (NLR), which suggests immune activity in the arteries. The ratio rises as testosterone falls.¹⁷

Another way we know low testosterone causes inflammation is by the fact that adding it back in — through testosterone replacement therapy (TRT) — reduces inflammation measurably. At least six months of testosterone therapy has been consistently linked to lower CRP in men with low testosterone levels.¹⁸

Testosterone improves insulin sensitivity

Testosterone helps regulate blood sugar by maintaining lean muscle, the body’s primary glucose disposal system. Every time you eat or exercise, your muscles absorb excess sugar from the bloodstream and convert it into energy for muscle contractions or store it as glycogen for future. Testosterone keeps muscles using glucose efficiently, so blood sugar stays in a healthy range.

When testosterone drops, muscles become less effective at absorbing glucose. Blood sugar runs higher, and the body has to pump out more insulin — the hormone that signals cells to absorb glucose — to keep blood sugar in a healthy range. Over time, that cycle can lead to insulin resistance. 

Insulin resistance promotes the production of small, dense LDL cholesterol particles, which are far more likely to penetrate artery walls and trigger the plaque buildup that leads to atherosclerosis (the hardening and narrowing of the arteries). Standard LDL cholesterol particles are larger and fluffier and bounce through arteries without causing damage. 

Testosterone affects blood flow and clotting

Low testosterone disrupts blood flow in several ways that directly harm your heart. In addition to stiffening arteries, restricting circulation, and accelerating plaque buildup, it raises levels of hematocrit, and increased levels are linked to blood clots. It also raises levels of fibrinogen — a protein that promotes clot formation — while reducing the body’s ability to dissolve clots that do form. And because testosterone signals bone marrow to produce red blood cells, low testosterone levels lead to fewer oxygen-carrying red blood cells reaching the heart.

Heart-Safe Testosterone 

The myth that TRT is bad for your heart traces back to bodybuilders and athletes taking 5–10 times a normal dose, unsupervised.¹⁹ 

Restoring low testosterone to a healthy range under medical supervision is safe and effective. The TRAVERSE study — a large randomized trial of 5,000+ men — found that testosterone therapy did not increase rates of major cardiovascular events such as heart attack or stroke compared to placebo, even in men with existing heart risk.²⁰

Optimizing testosterone for heart health

Staying in the optimal testosterone range with TRT requires regular tracking of both total testosterone and free testosterone, the portion that’s available for your body to use.²¹

It also requires monitoring levels of hematocrit, cholesterol and lipid ratios, blood sugar and insulin markers, as well as inflammatory markers, to make sure all stay in a healthy range.²² If hematocrit creeps up, for example, which it sometimes does, it’s easily corrected with a dose adjustment or therapeutic phlebotomy (a medical treatment that removes specific amounts of blood to manage conditions like iron overload). 

Healthy lifestyle habits, including diet, exercise, and stress management, support healthy testosterone production and influence how well the body responds to treatment.^{23 24 25}

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About the author

Dr. Abid Husain is a Consulting Physician and Scientific Advisor for Hone Health. As a triple-board-certified cardiologist and integrative medicine physician, Dr. Husain combines his background in traditional cardiology with functional medicine to offer a unique, multi-faceted modality of care.