Blood sugar: More than just a diabetes marker

From the desk of
Robb Wolf
ScienceBlood sugar: More than just a diabetes marker

To say it pays to keep your blood sugar within healthy ranges would be an understatement. Most people think of high blood sugar as a marker primarily for diabetes risk, but it’s also relevant for heart disease, cancer, dementia, and many other diseases. Your blood sugar is a snapshot of your metabolic health, and your metabolic health varies directly with your overall health.

But unless you’ve measured your blood sugar response to different foods, it may be difficult to connect with what I’m saying at a visceral level. You can’t typically feel when your blood sugar shoots past 125 — it just happens, and your body pays the price over the long term.

With all of that in mind, it’s important to understand this: managing blood sugar isn’t just about cutting out refined sugar. Exercising, avoiding snacks near bedtime, and sleeping well are also important. In this article, I’ll cover blood glucose basics, insulin resistance, chronic disease risk, how to measure your blood sugar, and 6 tips to help you keep blood sugar within a healthy range.

What Is Blood Sugar?

Glucose is a type of carbohydrate called a monosaccharide, or simple sugar. This critical energy source is made by plants through photosynthesis and stored. When it’s eaten by animals, that glucose winds up in the bloodstream as blood glucose, AKA blood sugar — the primary marker doctors use to assess diabetes risk.

We all require a bit of glucose in our blood, which provides a constant stream of fuel to our brain. Dangerously low blood sugar levels (called hypoglycemia) can even be fatal. If someone is fat adapted — meaning they can efficiently use dietary and body fat for energy — they may require less. But even these folks need some glucose for certain tissues like red blood cells.

Glucose is also an essential factor in a process called glycolysis — the first step of cellular respiration, which occurs in almost every cell of every living organism. Glycolysis creates energy by converting glucose to pyruvate, which is then converted to the two primary energy currencies for the human body: ATP and NAD.

That said, we don’t have to eat glucose directly to maintain blood sugar and energy levels. It can also wind up in our blood through two different processes:

  1. Glycogenolysis: the release of stored glucose (glycogen) from muscle and liver cells.
  2. Gluconeogenesis: the creation of glucose in the liver from materials like lactate and protein.

These are our glucose backup systems, for when you need to normalize blood sugar lows. But how does the body regulate incoming glucose to keep a stable blood sugar? That’s where a little hormone called insulin comes in.

Blood Sugar, Insulin, and Insulin Resistance

If blood sugar was to rise unchecked — say, from a never-ending supply of ice cream — consequences would follow. But thankfully, healthy folks’ pancreas will take notice of the incoming sugars and release insulin. Insulin’s job is to pull glucose out of the blood and into muscle and liver cells. Up to a point, you’re able to store this glucose as glycogen. The limit appears to lie around 500 grams of storage space.

This is a helpful mechanism for decreasing blood sugar to more manageable levels. However, if you max out your glycogen stores, glucose is instead moved into adipose tissue. Basically, insulin starts storing blood sugar as fat. That’s one consequence of a high-sugar diet.

Another consequence? A complicated condition called insulin resistance, in which the body’s cells no longer respond normally to insulin. As a result, the mess of blood glucose piles up, and to keep up with that mess the pancreas must release ever-increasing quantities of insulin.

High Blood Sugar and Chronic Disease Risk

When someone is insulin resistant, their ability to dispose of glucose via insulin is impaired. That means their blood sugar stays high. Fat storage is your body’s last plea to mitigate that. From there, it’s a short hop to the metabolic disease called type 2 diabetes.

The main signs of type 2 diabetes are:

  • Hyperglycemia (high blood sugar levels)
  • Hyperinsulinemia (high insulin levels)
  • Insulin resistance
  • Obesity
  • High triglycerides
  • Low HDL cholesterol
  • Higher risk of death and chronic disease

About 30 million Americans have type 2 diabetes. What’s worse, it further many other health problems:

  • Heart disease. It’s the number one cause of death in type 2 diabetics. High blood sugar drives inflammation that accelerates the formation of arterial plaques.
  • Cancer. High insulin levels (which follow high blood sugar levels) are linked to accelerated tumor growth.
  • Cognitive decline. Hyperinsulinemia, or high Insulin levels, predict cognitive impairments in the children of people with dementia.

For the rest of this article, let’s get practical. How can we best measure and manage blood sugar?

How To Measure Blood Sugar

If you want to measure your blood sugar, there are four main tests:

  • Fasting Blood Glucose: Your blood sugar level after at least twelve hours of fasting.
  • Postprandial Blood Glucose: Your blood sugar level 1 to 1.5 hours after eating a meal.
  • Oral glucose tolerance test (OGTT): Your blood sugar level 2 hours after drinking 75 grams of liquid glucose.
  • Hemoglobin A1c (HbA1c): Your average blood sugar over several months. HbA1c assumes that blood cells live for three months, but since that varies from person to person, HbA1c is imperfect.

To measure fasting or postprandial blood sugar, simply use a finger-prick device at home. For HbA1c, you can also order an at-home testing kit. On the other hand, the OGTT requires a lab visit.

What’s A Healthy Blood Sugar Level?

Insulin resistance and many of its associated problems can brew for months or even years before we see blood glucose elevations. Heightened blood sugar is a sign that the system has largely tapped its ability to handle excess calories and glucose levels.

So now that you have your blood sugar numbers, what’s do they mean? The American Diabetes Association (ADA) classifies diabetes risk in terms of fasting blood glucose (FBG) and HbA1c:

  • Normal: FBG under 100 mg/dl, HbA1c under 5.7%
  • Prediabetes: FBG from 100 to 125 mg/dl, HbA1c from 5.7% to 6.4%
  • Diabetes: FBG over 125 mg/dl, HbA1c over 6.4%

But when you look at the data, you see that what the ADA considers normal isn’t exactly optimal. In one study of over 4000 people, HbA1c tests showed that folks with “normal” HbA1c levels (5.4-5.6%) had a higher risk of heart disease than those below 5%. Another large study found that people with an FBG from 95-99 mg/dl were 2.33 times more likely to develop diabetes than those below 85 mg/dl. I’d say that’s a pretty significant gap.

My view? Based on the science, healthy FBG is somewhere south of 90 mg/dl and healthy HbA1c is somewhere south of 5%. There are a lot of potential caveats to this, however, so use those figures as a baseline — medical professionals should be able to identify the exceptions. For us, it’s time for practical advice on managing blood sugar levels.

6 Tips to Keep Blood Sugar Within Healthy Ranges

Most of the strategies to keep blood sugar low are also strategies to promote longevity, and that’s no coincidence.

#1: Avoid refined carbs

When it comes to metabolic health, diet is paramount. The sugar-loaded Standard American Diet (SAD) is metabolic enemy number one when it comes to spiking your blood sugar. Sucrose is everywhere, and there’s nothing like pastries, sodas, bread, and fruit juice to provide a whopping hit of high-fructose corn syrup. Even a moderate amount of fructose impairs insulin function.

My advice? Eat mostly whole foods, and you’ll crave processed foods less.

#2: Exercise

Exercise of all types can improve blood glucose regulation. When you use your muscles — particularly for intense exercise — you activate GLUT4 receptors in your muscle cells. These receptors clean up blood sugar faster than a dog laps up a plate of fallen food.

In one study, researchers found that just three sessions per week of high-intensity interval training (HIIT) dramatically improved insulin sensitivity in older adults. And if you’d rather go easy, that can be beneficial too. Just one session of low-intensity weight lifting improved blood sugar regulation in type 2 diabetics.

#3: Get enough sleep

Most people need 7–9 hours of shuteye each night for optimal health. When you’re sleep-deprived, insulin function suffers and ghrelin — a hunger hormone — is upregulated. Sugar is easy to overdo as-is. Don’t pair it with an increased appetite and weakened insulin function.

These are only a couple of reasons why sleep is important. The full list (unlike us) is nearly inexhaustible, so set a bedtime and be consistent.

#4: Try a low-carb or keto diet

According to a 2019 consensus report published in the journal Diabetes Care, low-carb diets are the intervention with “the most evidence” for combating high blood sugar in type 2 diabetics. My favorite piece of evidence is a study from 2018. It found that one year of supervised Keto dieting reversed type 2 diabetes (as measured by HbA1c) in 60% of 218 patients. Just as impressive: 94% of them were able to reduce or eliminate their supplemental insulin.

Keep in mind, these were medically supervised low-carb diets, which is important if you have type 2 diabetes. If you want to nerd out on this topic, check out this article on keto for type 2 diabetics.

#5: Consider intermittent fasting

I also covered intermittent fasting (IF) for type 2 diabetes. Why? Intermittent fasting has similar metabolic effects to keto. By taking breaks from food (especially carbs) you keep blood sugar and insulin levels low. This helps stave off the insulin resistance spiral I covered earlier, but this is not via some kind of magic. IF is, first and foremost, a tool for calorie control.

Fasting can help you stay metabolically flexible, but be careful not to overdo it. Fourteen to eighteen hours seems to be the sweet spot for active folks seeking to maintain muscle, assuming they’re strength training and consuming adequate protein. Anything longer and you risk losing lean mass.

#6: Spices and supplements

A variety of foods and supplements have been shown to help with blood sugar management, including collagen, berberine, cinnamon, and curcumin (turmeric).

Mastering Your Blood Sugar

If you want to be the master of your health, blood sugar should grab your attention. It’s a top 5 biomarker for healthy aging. To stay in good standing simply exercise, eat nutrient-dense whole foods, avoid sugar, and get enough sleep. You may also consider a low-carb diet, or perhaps fasting intermittently. Form these good habits and not only will you have more consistent energy, but you’ll also set yourself up for a longer, healthier life. That’s how our ancestors stayed metabolically flexible, and it’s how you can too.

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