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 typically can’t feel when your blood sugar shoots past 125—it just happens, and your body pays the price in the long term. An interesting exception? Many folks notice vision and hearing issues following rapid increases in blood sugar, which negatively affect our eyes, nerves in our ears, and other tissues too.
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—a simple sugar with the molecular formula C6H12O6. Plants make glucose via photosynthesis, then they store it for energy. When animals eat plants, it ends up in their bloodstream as blood sugar (aka blood glucose). The amount of glucose circulating in your blood is the primary marker doctors use to assess diabetes risk.
Glucose is a critical source of energy. Through a process called glycolysis, glucose is converted to pyruvate, which is then converted to ATP and NAD—the two primary energy currencies for the human body. We need glucose in our blood to live. Dangerously low blood sugar levels (called hypoglycemia) can be fatal. There IS a bit of wiggle there if an individual is fat adapted, but even for the most keto-adapted individual some glucose is necessary for certain tissues such as red blood cells.
That said, we don’t have to eat glucose directly to maintain blood sugar levels. It can also end up in our blood through a couple of processes:
- Glycogenolysis: the release of stored glucose (glycogen) from muscle and liver cells.
- Gluconeogenesis: the creation of glucose in the liver from materials like lactate and protein.
These are our glucose backup systems. They kick in to help normalize blood sugar lows. But how does the body regulate blood sugar levels? That’s where a critical hormone named insulin comes in.
Blood Sugar, Insulin, and Insulin Resistance
If blood sugar was to rise unchecked, consequences would follow. But under ideal circumstances, your pancreas takes notice and release insulin. Insulin then helps pull glucose out of the blood and into muscle and liver cells to be stored as glycogen, decreasing blood sugar to more manageable levels.
However, when your glycogen stores are full (maxing out at around 500 grams), 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 the pancreas must release increasing amounts 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
- 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 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. The Keto-Mojo meter and the Precision Xtra meter are both good options. 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 recommendation? Eat mostly whole foods, and you’ll crave processed foods less.
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 per night for optimal health. When you’re sleep-deprived, insulin function suffers and ghrelin—a hunger hormone—is up-regulated. 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
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, get enough sleep, and consider fasting intermittently. 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.