Is insulin resistance the first sign of heart disease? A growing body of evidence says it is.
Back in 2012 when cardiologist Steven Sinatra, MD, and I wrote our book, The Great Cholesterol Myth, I was pretty certain that testing for “good” and “bad” cholesterol was out of date, and that our belief in its value was no longer justified. “Bad” cholesterol was a lousy predictor of heart disease, was inaccurately named, and was certainly not enough on which to base a prescription for a powerful drug.
But I confess, I wasn’t 100 percent sure what we should be looking for. Now I am. It’s insulin resistance. Let me explain.
Insulin resistance is to heart disease what smoking is to lung disease
Insulin resistance (IR) doesn’t account for all cases of heart disease any more than smoking accounts for all incidences of lung cancer. But it tracks with and predicts cardiovascular disease better than any other variable yet studied. And it shows up earlier. As a predictive marker, it blows “bad” cholesterol out of the proverbial water.
In the new and revised edition of our book—due out in 2021—we painstakingly detail the research showing that IR predates cardiovascular disease with startling consistency. In fact, the connection is so obvious and demonstrable that we consider insulin resistance syndrome as one, if not the primary, cause of heart disease. It’s been hiding in plain sight for a very long time.
When you have IR, you have some degree of dysfunction in your body’s ability to metabolize carbohydrates. IR is the opposite of insulin sensitivity, which is a desirable metabolic state where your body metabolizes carbs just fine. So the best way to explain IR is to spend a minute looking at how insulin sensitivity works so we can see what goes wrong in IR (and why it matters so much to your health).
So what is insulin resistance?
Let’s take a look at the undamaged metabolism of a healthy 8-year-old kid back in the days before the internet and play dates. The kid comes home from third grade and eats an apple, which raises his blood sugar a little, causing his pancreas to react by releasing a little squirt of a hormone called insulin.
One of insulin’s main jobs is to round up the excess sugar in the bloodstream and deliver it into the muscle cells where it can be “burned” for energy. That’s just fine and dandy for our 8-year old, since he’s going to be climbing on monkey bars and playing tag, so his muscle cells eagerly welcome the fuel. Eventually, his muscles use up the sugar provided by the apple, so his blood sugar is now slightly lower than normal, which makes him hungry. He goes home and eats a healthy dinner, and all is right with the world. End of story.
In this case, our hypothetical boy’s insulin-sensitive metabolism is working as it ought to. But in at least half of today’s population, that’s no longer the case.
Let’s look at that same kid 30 years later. He wakes up late, stress hormones already coursing through his body. Those stress hormones send a message to his brain to fuel up for an anticipated emergency (read: stock up on fat!). He runs out the door and stops at the local coffee emporium for a pumpkin spice latte (380 calories, 49 grams of sugar) and a lowfat blueberry muffin (350 calories, 55 grams of carbs, 29 grams of sugar).
His blood sugar takes off like the Challenger. The pancreas says, “Code Red! Send out the big guns! This dude just ate the equivalent of ten packs of Ding Dongs!” The pancreas produces a bucketful of insulin in a desperate attempt to get all that sugar out of the bloodstream and deliver it to the muscles. The problem is, his muscle cells aren’t having it.
“What do we need all this sugar for?” they seem to be asking. “The only ‘exercise’ this guy’s gonna get all day is pushing a computer mouse, and when he goes home, he’s going to sit on the couch and play with the TV clicker. The last thing we need here is more fuel.”
So the muscle cells begin to resist the effects of insulin. “Thank you but no thank you. We don’t need it. Go somewhere else.” And insulin has no choice but to take its sugar payload to another location, and guess where that is? The fat cells. Which happily welcome the sugar in.
Fat, Inflammation, and Blood Sugar
Fat cells are actually endocrine organs, and they secrete a ton of inflammatory
chemicals. Inflammation is one of the major causes and promoters of heart disease. And making your fat cells bigger makes them even more powerful inflammation factories.
For a while, your blood sugar levels may stay in the normal range, as the pancreas valiantly tries to pump out enough insulin to keep up with this massive dietary sugar influx. Your blood sugar may still be hanging on in the “normal” range, but the high levels of insulin—which your doc may not be testing for—tell you that the whole thing is about to come tumbling down. (You can think of chronically elevated insulin as the body’s way of shouting “Help!”)
Eventually, insulin won’t be able to keep blood sugar in the “normal” range anymore, and blood sugar will start to rise. Now your blood sugar is high (because all that sugar has nowhere else to go), your insulin is also high, and you’re well on your way to a diagnosis of full-blown diabetes.
In other words, insulin resistance syndrome is “pre-diabetes.” And pre-diabetes is “pre-heart disease.” According to the American Heart Association, at least 84 percent of diabetics die from cardiovascular disease, and that numberis undoubtedly a low estimate, since at least 33 percent of people with diabetes are walking around undiagnosed.
“Emerging evidence shows that insulin resistance is the most important predictor of cardiovascular disease and type 2 diabetes,” says Robert Lustig, MD, pediatric endocrinologist, and professor in the Department of Endocrinology at the University of California, San Francisco.
Testing for Insulin Resistance
There are ways you can test for IR right now, with nothing more than the numbers you already have on your basic blood test.
One good “surrogate measure” is to calculate the ratio between your triglycerides and your HDL (so-called “good cholesterol”). Divide triglycerides by HDL—so for example, if triglycerides are 150 and HDL is 50, your ratio is 3. A ratio of 2 (or less) is superb and shows low likelihood for IR and little risk for a heart attack. A ratio of 5 means it’s time to pay attention to your diet.
Second way: Stand a few feet in front of a wall, and walk straight toward it.
If your belly hits the wall before your nose does, you are insulin-resistant.
Third way: Order an inexpensive lab test called fasting insulin. Take the result, together with your fasting glucose (available on practically every blood test your doctor ever ordered), and plug those two numbers into an online calculator called a HOMA-2 calculator. It will give you an IR score, just like a BMI calculator tells you your BMI based on height and weight.
The state-of-the-art way—the one I recommend if at all possible—is the LP-IR test given by LabCorp (labcorp.com). Ask your doctor to order it.
What to Do About Insulin Resistance
The best news about IR is that if you identify it early, you can turn it around. And you can do that without drugs. It’s completely modifiable by diet—specifically, a low-carb, high-fat diet, which can (and usually does) reverse IR. You just need to find a low-carb eating plan that works for you. And stick with it. (Shameless plug: the recently released 4th edition of my book Living Low Carb can help.)
If you focus on lowering insulin resistance, you will be doing your heart a much bigger favor than if you focus on lowering your LDL cholesterol. Emerging evidence—and clinical experience—is showing that insulin resistance shows up well in advance of other markers for heart disease, including elevated blood sugar, A1C, triglycerides, and disordered blood lipids. So pay attention!
And do me a favor—when the link between IR and heart disease finally becomes accepted in the medical establishment, please just remember one thing: You heard it here first.
6 New Ways to Love Your Heart
1. Amla
This vitamin C-rich berry (Phyllanthus emblica) does a heart good, says new research in BMC Complementary and Alternative Medicine. The placebo-controlled study involved 98 participants with markers of high lipids such as triglycerides, fat phospholipids, and/or cholesterol. Of the 49 people taking a full-spectrum amla extract (500 mg twice daily), 73% showed significant reduction in their total cholesterol levels. And 44 of the 49 subjects in the amla group lowered their triglycerides.
2. Transcendental Meditation
Meditate on this: Patients with coronary heart disease who included Transcendental Meditation (TM) with their cardiac rehabilitation program increased blood flow to the heart by more than 20%, according to a study in the Journal of Nuclear Cardiology. TM is a specific type of meditation.
3. Blueberries
Here’s some berry good news: Eating 1 cup of blueberries daily can lower risk factors for heart disease by 15 percent. The study was performed at the University of East Anglia, in collaboration with colleagues from Harvard and across the UK. Interestingly, researchers found no benefit to a smaller serving daily, such as a half-cup of berries.
4. Aged Garlic Extract
If you have heart disease or type 2 diabetes, you may find that wounds don’t heal as quickly as they should. The problem? The microcirculatory system that carries blood from blood vessels to the tissues can be compromised, limiting blood flow to the site of wounds. Garlic to the rescue: According to new research conducted at Lund University’s Skåne University Hospital in Sweden, Kyolic Aged Garlic Extract (AGE) can increase microcirculation in these at-risk patients.
5. Tooth Brushing
Regular tooth brushing may keep A-fib away. A study in the European Journal of Preventive Cardiology found that people who brushed their teeth three or more times daily had a 10 percent reduced risk of A-fib and a 12 percent lower chance of heart failure. “Poor oral hygiene can provoke transient bacteremia and systemic inflammation, a mediator of atrial fibrillation and heart failure,” says study author Dr. Tae-Jin Song of Ewha Womans University in Seoul, Korea.
6. Chili Peppers
Spicy hot equals heart-healthy. According to a large-scale Italian study in the Journal of the American College of Cardiology, people who eat more chili peppers on a regular basis have a whopping 40 percent lower risk of dying from a heart attack. The chance of stroke was nearly 50 percent lower among chili pepper lovers too.
Written by Ned Johnson and William Stixrud for Better Nutrition and legally licensed through the Matcha publisher network. Please direct all licensing questions to legal@getmatcha.com.