What Diabetes Does To Your Heart

We’ll get straight to it: researchers (Dr. Jasmine Khor et al.) have found that type 2 diabetes physically remodels the human heart by disrupting energy production, weakening muscle structure, and increasing fibrous tissue (that is also bad), which, together, push the heart towards failure.

So, how does it do that and how can we avoid that unfortunate outcome?

At the heart of things

Type 2 diabetes reshaping the heart fits neatly into the bigger picture of metabolic syndrome, which absolutely bears mentioning because people tend to talk a lot about the parts, without talking about how it all comes together.

Metabolic syndrome is the name given to a cluster of energy-handling (thus: metabolic) problems—high blood sugar, insulin resistance, abdominal fat, abnormal lipids, and high blood pressure—which all strain the same biological systems. And yes, the effect compounds, with each part making the others worse, unless reversed.

In metabolic syndrome, cells across the body become less responsive to insulin, and the heart is no exception: it struggles to switch fuels efficiently, overworks its mitochondria, and gradually stiffens as fibrous tissue builds up. Over time, this energy mismatch and low-grade inflammation quietly remodel the heart muscle, making it less flexible and less efficient at pumping blood.

With that in mind, metabolic syndrome is not just a collection of risk factors on a checklist, but rather also a slow-motion metabolic stress test for the heart—one that can, if neglected, tip the heart from adaptation (i.e. dealing with problems better) into failure (i.e. literally, heart failure).

The aforementioned researchers at the University of Sydney analyzed donated human heart tissue from transplant recipients and compared it with tissue from (formerly)* healthy donors, allowing direct observation in humans rather than merely non-human animal models.

^{*Formerly healthy because, of course, the donors are dead. But what this means is that they died in otherwise good health, as can happen if accident or incident should befall.}

What they found is that diabetes alters how heart cells generate energy by reducing insulin sensitivity in glucose transporters, increasing stress on mitochondria, and worsening the metabolic profile seen in advanced heart failure.

As part of this, diabetes also reduces key proteins involved in contraction and calcium regulation while promoting fibrosis, making the heart muscle stiffer and thus less efficient at pumping blood. These direct, tissue-level changes help explain why people with type 2 diabetes face a much higher risk of heart failure, beyond the shared risk factors alone.

You can read the paper in full, here: Left ventricular myocardial molecular profile of human diabetic ischaemic cardiomyopathy

What to do about it?

Here are some very good starting points:

• What Matters Most For Your Heart? ← perhaps not coincidentally, this is also what matters most for avoiding/reversing type 2 diabetes
• The Two Worst Things For Cardiac Aging
• Three Tweaks To Cut Diabetes Risk By 1/3

Want to learn more?

For a much deeper dive, you might like this excellent book we reviewed a while back:

Why We Get Sick – by Dr. Benjamin Bikman ← the title doesn’t really give it away, but we promise this book is very much specifically about this very topic, the science of how insulin resistance (not even the blood sugar imbalances that may result, but the insulin resistance itself already) leads to an increase in most other health risks (especially of the cardiometabolic variety), and why it’s a bigger problem sooner than people think from blood sugar tests alone, and what to do about it

Take care!