If you want to quantify your diabetes risk, you’ll need to measure your blood glucose levels. Depending on what number comes back, you’ll be lumped into one of three categories: normal, prediabetes, or full blown diabetes.
These categories are set by the American Diabetes Association (ADA), but they aren’t necessarily gospel. In fact, there’s considerable debate on what blood glucose — or blood sugar — levels are optimal for your health.
Right now you’re probably wondering what blood glucose levels, according to the research, are optimal levels. You might also be wondering how to test for these levels. And how to reduce your diabetes risk. You may even be wondering what, exactly, it means for a person to have diabetes.
Understandable. Diabetes is a complex disease involving high blood sugar, high insulin, and weight gain — and it can’t be explained in sentence or two.
This guide will help you understand all the basics. In this article, you’ll learn learn:
Glucose, a particle with the molecular formula C6H12O6, is classified as a simple sugar. Specifically, glucose is a monosaccharide — a form of carbohydrate. Glucose gets made via photosynthesis, and it’s how plants store energy.
Animals make and store glucose for energy too. But unlike plants, animals also consume glucose directly. That rice you had the other night? More or less pure glucose.
Right. When you eat carbs, you’re eating glucose.
So where does that glucose end up? Well, after it gets digested, it ends up in your blood – and now it’s called blood glucose, or blood sugar. (Note: I’ll be using blood glucose and blood sugar interchangeably. They mean the same thing).
There are two other ways, besides eating, that glucose ends up in your blood:
- Glycogenolysis: a fancy term for your body releasing stored glucose, or glycogen, for use as immediate energy during a fast or exercise session [*].
- Gluconeogenesis: a process, occurring mostly in your liver, for converting non-glucose compounds (like lactate) into glucose to meet your energy needs.[*] This is helpful when, you’ve been fasting, your blood sugar is running low, and you’ve depleted all your glycogen. Yes, your body can make its own glucose.
Glucose gets used as “energy” through a process called glycolysis. Glycolysis is a chemical reaction that turns glucose into pyruvate, a molecule used to form ATP and NADH — both energy sources for your cells.[*]
Okay, high school chemistry lesson is over for now.
So far, you’ve learned that glucose becomes blood glucose when you:
- Digest food, especially carbs [*]
- Release stored glucose via glycogenolysis
- Make your own glucose via gluconeogenesis
After glucose arrives in your blood, this is what happens next:
Blood Sugar, Insulin, And Fat Storage
When you eat a meal, your blood sugar rises — and this signals beta cells in your pancreas to release the hormone insulin. Insulin wears many hats in the human body, but the main hat is the blood sugar regulation hat. Healthy blood sugar levels help keep you healthy and disease free.
That’s where insulin comes in. Insulin gets blood glucose out of your blood and into your liver, muscle, and fat cells to be socked away for future energy.
How does insulin accomplish this task? By binding to special receptors on your cells. Then these receptors activate transporters — GLUT 4 transporters — that physically drag blood glucose into the cell. Once inside the cell, that glucose gets converted into one of two forms of stored energy: glycogen or fat[*].
Glycogen is the preferred storage form of glucose, and your body can store around 500 grams between your muscle and liver cells.[*] So glycogen is stored fuel, and glycogenolysis, if you recall, is when that stored fuel gets converted back to glucose and released for energy. This happens when you’re fasting, exercising intensely, or both. Then glycogen stores are refilled with glucose.
When glycogen stores become full, blood glucose gets stored as fat. Especially if there’s lots of insulin around. This adaptation allowed our ancestors to pile on adipose tissue (stored energy) for future times of scarcity. In times of feast, they prepared for times of famine.
But this ancient adaptation can backfire. If it’s always feast and never famine, your blood glucose and insulin levels spin out of control. And then you’re looking at increased risks for diabetes, heart disease, and other chronic conditions.
This is how that happens:
Chronically high blood sugar can lead to several life-threatening lifestyle diseases:
#1: Blood Glucose And Insulin Resistance
Recall that insulin’s job is to regulate blood glucose. Insulin moves blood glucose out of the blood and into your cells.
But like you, me, and anyone working for an investment bank — insulin can get overworked. This happens when (and I’m saying it again) you eat too many carbs. Then your blood sugar rises, and your pancreas pumps out loads of insulin to handle the situation.
Unfortunately, when insulin levels stay too high for too long, your cells get tired of hearing from insulin every waking second. Insulin, in other words, has become the annoying telemarketer that’s called four times this week.
And how do you stop a persistent telemarketer? You block their number.
In the same way, when insulin keeps calling, your cells eventually block insulin’s number. They stop listening to insulin, and stop shuttling glucose out of your blood.
This condition is called insulin resistance, and it means that blood glucose is no longer efficiently transported into your cells. Instead, glucose gets stuck in your bloodstream, which is dangerous for reasons you’ll soon learn.
Insulin resistance, by the way, is synonymous with metabolic syndrome. When you’re insulin resistant, you have high blood glucose levels (hyperglycemia), high insulin levels (hyperinsulinemia), and a high propensity to put on fat. All of these factors are linked to diabetes and a host of other chronic diseases.
#2: Diabetes And Other Diseases Linked to Hyperglycemia
According to the CDC, over 29 million Americans have diabetes. Believe it or not, 25% of them don’t even know they have this condition[*].
To be clear, there are two main types of diabetes. Type 1 diabetes is when the pancreas can’t produce insulin. Because of this, type 1 diabetics need supplemental insulin to regulate their blood sugar.
Type 2 diabetes, on the other hand, is simply a bad case of insulin resistance. The main features of type 2 diabetes include:
- Insulin resistance
- Hyperglycemia (high blood sugar levels)
- Hyperinsulinemia (high insulin levels)
- Increased mortality risk and risk for other chronic diseases [*]
These features of diabetes are inextricably linked. Hyperglycemia, for instance, leads to insulin overproduction, which in turn causes your cells to become insulin resistant. And it all starts, in many cases, with eating too many carbs[*].
Why do diabetics have weight issues? If you recall, insulin is a fat-storage hormone — and with lots of insulin around, your body can’t burn fat. Instead, it adds fat.
Yet diabetes isn’t the only concern for those with dysregulated insulin and blood glucose. Here are a few other chronic diseases linked to high blood sugar:
- Heart Disease: Cardiovascular disease is the number one killer of type 2 diabetics, and high blood glucose levels appear to be a causative factor. Controlling blood glucose, then, should be part of any heart health program[*].
- Dementia: Hyperinsulinemia, a consequence of high blood sugar, is a proven risk factor for cognitive decline. In middle-aged children of dementia patients, more insulin was linked to more brain damage[*].
- Cancer: Insulin resistance and diabetes have been linked to cancerous tumor growth. The mechanism is not fully understood, but likely involves insulin’s positive effect on insulin-like growth factor (IGF) — a molecule that causes cells (including cancer cells) to proliferate[*].
Up to now, you’ve learned about high blood glucose. Next, you’ll see what it means to have high blood glucose, what it means to have normal blood glucose, and how you go about measuring blood glucose.
So you want to measure your blood glucose levels, eh? Okay cool. There are four main tests for that:
- Fasting Blood Glucose – this is your blood sugar level in the absence of food, typically after at least twelve hours of fasting. Also known as fasting blood sugar.
- Postprandial Blood Glucose – your blood sugar level after a meal. Postprandial blood glucose is the highest from 1 to 1.5 hours after eating a meal[*]. Again, carb-rich meals spike blood glucose the most.
- Oral glucose tolerance test (OGGT or GTT) – your blood sugar response two hours after drinking 75 grams of pure liquid glucose. Unless your dinner looks like a bowl of sugar cubes, though, this glucose test isn’t super applicable to real life.
- Hemoglobin A1c (HbA1c) – a measure of your average blood sugar level over the past few months. HbA1c is based on the assumption that blood cells live for three months, though this isn’t always the case[*].
Fasting, postprandial, and HbA1c glucose testing are simple blood tests, and can all be done at home using a glucose meter from your local drug store. Just prick your finger, put a drop of blood on a test strip, insert the strip into the meter, and out pops your blood glucose number[*].
The accuracy of home testing, however, varies from device to device. For more reliable results, consider having your blood drawn and analyzed at a lab[*].
Okay, so now you’ve got your blood glucose numbers. From the perspective of diabetes risk, what do they mean?
What’s Normal Blood Glucose? (And What’s Diabetic?)
This is what the American Diabetes Association considers normal, prediabetic, and diabetic for 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 here’s the thing. When you look at the research, the ADA’s “normal” blood glucose levels start to look, from the perspective of human health, somewhat abnormal.
Take fasting blood glucose. In one large observational study, those with FBG levels from 95-99 mg/dl were 2.33 times more likely to develop diabetes than those with FBG levels below 85 mg/dl[*]. Bottom line? If you’re telling me a FBG of 97 is normal, I ain’t buying.
Another study, this time on HbA1c. Following 4,060 people over 3.5 years, researchers found that those with HbA1c levels under 5% had significantly lower levels of heart disease than those in the mid 5%s[*]. The ADA sanctions HbA1c levels under 6%, but it appears your heart would rather be under 5%.
Given this data, optimal fasting blood glucose is likely somewhere below 85 mg/dl and optimal HbA1c is likely somewhere below 5%.
How can you keep your blood sugar at healthy levels? Follow these tips:
#1: Exercise Benefits Blood Glucose
Along with fasting, exercise — either resistance or endurance training — is a proven strategy for improving blood glucose regulation. For instance, endurance training in a fasted state has been shown to have profound effects on glucose tolerance and insulin sensitivity[*]. All the more reason to work out before breakfast.
But you needn’t fast to benefit from exercise. In one study, researchers found that a single session of low-intensity resistance training (Read: easy weight lifting) significantly improved blood sugar regulation in type 2 diabetics[*]. So when it comes to blood glucose, perhaps you don’t need to go hard to get results.
Though sometimes it does pay to go hard. In fact, high-intensity interval training (sprinting) can dramatically improve insulin’s ability to handle blood sugar. Just three sessions a week appears to do the trick[*].
Why does exercise have these positive effects on blood sugar? Think cellular. Exercise activates GLUT 4 transporters in your muscle cells — which then shove blood glucose out of your blood and into your muscles.
Now to the question on your mind: how does diet affect blood glucose?
#2: Dietary Considerations For Blood Glucose
When it comes to healthy blood sugar, nutrition is the number one variable under your control, so you’ll want to get it right.
This is how fasting, carbs, protein, and fat affect your blood sugar levels:
Intermittent Fasting and Blood Glucose
Eating raises your blood sugar, so it follows that not eating for an extended period keeps your blood sugar at lower, healthier levels. It’s that simple.
The science bears this out. Intermittent fasting — or fasting for 12 to 24 hours on a daily or semi-daily basis — has been shown to improve fasting blood glucose levels in middle-aged men with metabolic syndrome[*]. Why? Because fasting decreases insulin resistance, which helps your cells deal with excess blood sugar.
Practicing intermittent fasting is easier than it sounds. Just stop eating after dinner, and don’t eat again for at least 12 hours.
Eventually, of course, your fast must end — and when it does, you’ll be eating carbs, protein, or fat.
Carbs and Blood Glucose
Not to beat a dead horse, but a high carb diet can raise your blood sugar to dangerous levels (hyperglycemia), spike your insulin (hyperinsulinemia), and cause insulin resistance. Then you’re on your way to diabetes.
But it’s not just high carb diets at issue here. Even moderate portions of carbs, it’s been shown, impair blood glucose regulation[*].
Some carbs, however, are a bit healthier than others. For instance, carbs like beans with a low glycemic index — which raise blood sugar slower than pure sugar — are less likely to cause insulin resistance[*].
Protein and Blood Glucose
Protein raises blood glucose a little, but not nearly as much as carbohydrates.
And if you’ve heard that too much protein on a keto diet can kick you out of ketosis, that’s a little overblown.
Instead, protein is an excellent macro to help you feel fuller longer and help regulate your blood sugar and insulin response. In fact, high protein intake is associated with an improvement in overall glucose control in type 2 diabetics[*]
Fat and Blood Glucose
Of the three macronutrients, fat is the least likely to raise your blood sugar. A high fat diet, in fact, seems to be therapeutic for insulin resistance[*].
When you pair high fat intakes with very low carb intakes, the result is the ketogenic diet — a diet which gets your body burning fat and creating ketones. These ketones are then used by your cells, instead of glucose, for energy.
In fact, the ketogenic diet is so good for regulating blood sugar, it deserves its own section.
The jury is in: the ketogenic diet is great for blood sugar regulation, and even shows promise for treating type 2 diabetes[*]. Here are three reasons why:
#1: Keto Prevents Spikes and Crashes In Blood Sugar
The ketogenic diet is by definition a low carb diet — and when you don’t eat carbs, your blood sugar doesn’t fluctuate as much throughout the day. An example will help.
Take your average kid on Halloween. He’ll eat half his body weight in candy, bounce off the walls for a few hours, then crash like the Hindenburg around midnight.
His manic energy, of course, is due to high blood sugar. The crash? Right, low blood sugar. And unless people start handing out almonds to trick-or-treaters, this ritual is unlikely to change anytime soon.
But if, someday, it does change, I’m confident that even candy-loving children could become fat-burning beasts.
In one study, 28 overweight people with type 2 diabetes were put on a ketogenic diet for 16 weeks. What happened? After the study was over, the participants had 16% lower HbA1c levels. That’s significant[*].
In another study on type 2 diabetics, a low carb diet improved insulin sensitivity by a whopping 75%. Plus the diabetics showed improvements in fasting blood glucose and HbA1c levels[*].
#2: Keto Causes Weight Loss
It may sound counterintuitive, but it’s true: eating fat helps you lose weight. When you eat a high fat, ketogenic diet, your body adapts to burning fat for energy — and it becomes easier to drop those excess pounds.
This has been researched. In one study, researchers fed a ketogenic diet and a low glycemic (high carb) diet to two separate groups over 24 weeks. Results? The keto group showed larger reductions in fasting blood glucose and lost more weight than the low glycemic, high carb group[*].
#3: Keto Controls Appetite
How else does keto help with blood sugar and weight loss? By reducing your ravenous appetite.
Here’s how it works. When your body adapts to eating a high-fat diet, it also becomes better at burning its own fat stores. When you burn your own fat stores, you don’t get as hungry. And when you don’t get as hungry, you eat less.
For example, one group of diabetics were placed on a low carb diet — and ate about 1,000 fewer calories per day. They weren’t forced to eat less. They just did.
If you want to prevent insulin resistance, maintain a healthy weight, and reduce your risk of chronic diseases like diabetes and cancer — you’ll want to take your blood glucose seriously. You’ll want to master it. Here are some simple ways to do that:
- Measure your blood sugar with a glucose meter at home, or order a lab test for more accurate results
- Exercise with both resistance and endurance training
- Try intermittent fasting
- Limit your carbs — especially refined carbs
- Try the ketogenic diet
- Eat plenty of protein
- Eat plenty of healthy fats
- Eat foods and spices that improve blood sugar regulation like dark chocolate, cinnamon, green tea, and turmeric[*].
- Improve your blood sugar response even further with compounds like berberine and bitter melon
Glucose And Your Health
Glucose may be a simple sugar, but its effects on your health are far from simple.
Some effects, of course, are more straightforward than others. Your body uses glucose for immediate energy, or stores it away for future energy as glycogen or fat. But when too much glucose ends up in your bloodstream, things start to get more complicated.
Now you’re entering insulin resistance territory — which increases your risk for diabetes, cardiac disease, dementia, and cancer. All thanks to misregulation, and perhaps mismanagement, of your blood glucose.
These days, fortunately enough, it’s simple enough to test your blood glucose levels — then tweak your diet and exercise routine accordingly. Hopefully, the knowledge and tools in this article will help.
There’s a lot to remember here. But when memory fails, bookmarks do not. See you soon.