When Your "Normal" Blood Sugar Isn't Normal (Part 1) | Chris Kresser

When Your “Normal” Blood Sugar Isn’t Normal (Part 1)

by Chris Kresser

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In the next two articles we’re going to discuss the concept of “normal” blood sugar. I say concept and put normal in quotation marks because what passes for normal in mainstream medicine turns out to be anything but normal if optimal health and function are what you’re interested in.

Here’s the thing. We’ve confused normal with common. Just because something is common, doesn’t mean it’s normal. It’s now becoming common for kids to be overweight and diabetic because they eat nothing but refined flour, high-fructose corn syrup and industrial seed oils. Yet I don’t think anyone (even the ADA) would argue that being fat and metabolically deranged is even remotely close to normal for kids. Or adults, for that matter.

In the same way, the guidelines the so-called authorities like the ADA have set for normal blood sugar may be common, but they’re certainly not normal. Unless you think it’s normal for people to develop diabetic complications like neuropathy, retinopathy and cardiovascular disease as they age, and spend the last several years of their lives in hospitals or assisted living facilities. Common, but not normal.

In this article I’m going to introduce the three markers we use to measure blood sugar, and tell you what the conventional model thinks is normal for those markers. In the next article, I’m going to show you what the research says is normal for healthy people. And I’m also going to show you that so-called normal blood sugar, as dictated by the ADA, can double your risk of heart disease and lead to all kinds of complications down the road.

The 3 Ways Blood Sugar Is Measured

Fasting blood glucose

This is still the most common marker used in clinical settings, and is often the only one that gets tested. The fasting blood glucose (FBG) test measures the concentration of glucose in the blood after an 8-12 hour fast.

It only tells us how blood sugar behaves in a fasting state. It tells us very little about how your blood sugar responds to the food you eat.

Up until 1998, the ADA defined FBG levels above 140 mg/dL as diabetic. In 1998, in a temporary moment of near-sanity, they lowered it to 126 mg/dL. (Forgive me for being skeptical about their motivations; normally when these targets are lowered, it’s to sell more drugs – not make people healthier.) They also set the upward limit of normal blood sugar at 99 mg/dL. Anything above that – but below 126 mg/dL – is considered “pre-diabetic”, or “impaired glucose tolerance” (IGT).

Oral glucose tolerance test (OGTT)

The OGTT measures first and second stage insulin response to glucose. Here’s how it works. You fast and then you’re given 75 grams of glucose dissolved in water. Then they test your blood sugar one and two hours after. If your blood sugar is >140 mg/dL two hours later, you have pre-diabetes. If it’s >199 mg/dL two hours later, you’ve got full-blown diabetes.

Keep in mind these are completely arbitrary numbers. If your result is 139 mg/dL – just one point below the pre-diabetic cut-off – you’ll be considered “normal”. Of course this is perfectly absurd. Diabetes isn’t like catching a cold. You don’t just wake up one day and say, “I’m not feeling so well. I think I got a bad case of diabetes yesterday.” Like all disease, diabetes—and diabesity—is a process. It goes something like this:

malfunction > disease process > symptoms

Before your blood sugar was 139, it was 135. Before it was 135, it was 130. Etcetera. Would you agree that it’s wise to intervene as early as possible in that progression toward diabetic blood sugar levels, in order to prevent it from happening in the first place? Well, the ADA does not agree. They prefer to wait until you’re almost beyond the point of no return to suggest there’s any problem whatsoever.

[End rant]

The other problem with the OGTT is that it’s completely artificial. I don’t know anyone who drinks a pure solution of 75 grams of glucose. A 32-oz Big Gulp from 7-11 has 96 grams of sugar, but 55% of that is fructose, which produces a different effect on blood sugar. The OGTT can be a brutal test for someone with impaired glucose tolerance, producing intense blood sugar swings far greater than what one would experience from eating carbohydrates.

Hemoglobin A1c

Hemoglobin A1c, or A1c for short, has become more popular amongst practitioners in the past decade. It’s used to measure blood glucose in large population-based studies because it’s significantly cheaper than the OGTT test.

A1c measures how much glucose becomes permanently bonded (glycated) to hemoglobin in red blood cells. In layperson’s terms, this test is a rough measure of average blood sugar over the previous three months.

The higher your blood sugar has been over the past three months, the more likely it is that glucose (sugar) is permanently bonded to hemoglobin.

The problem with the A1c test is that any condition that changes hemoglobin levels will skew the results. Anemia is one such condition, and sub-clinical anemia is incredibly common. I’d say 30-40% of my patients have borderline low hemoglobin levels. If hemoglobin is low, then there’s less of it around to become bonded to glucose. This will cause an artificially low A1c level and won’t be an accurate representation of your average blood sugar over the past three months.

Likewise, dehydration can increase hemoglobin levels and create falsely high A1c results.

The “normal” range for A1c for most labs is between 4% and 6%. (A1c is expressed in percentage terms because it’s measuring the percentage of hemoglobin that is bonded to sugar.) Most often I see 5.7% as the cutoff used.

In the next article we’ll put these “normal” levels under the microscope and see how they hold up.

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  1. Hi. I was pre-diabetic with a 6.1 or 6.2% A1C and overweight for a number of years. I took off a lot of weight and at my last checkup my A1C was 5.6% (but my fasting glucose was 112). I decided to get a glucometer and monitor my glucose closely to see what’s going on. It is lowest before meals. I don’t eat breakfast – just coffee with milk – and before lunch and dinner its in the 90s. I eat salad for lunch and it doesn’t rise that much. Not higher than 110. After dinner, when I eat more carbs it rises more, like to 120-140 depending on what I eat, but it comes down to the low 100s within a couple of hours. The one time I had a very high carb dinner — a huge bowl of rice – it went up to 168 after an hour – then further up to 179 after 2 hours, but dropped to 129 after 2.5 hours. And it is NEVER low when I wake up in the morning after at least 8 hours of fasting. I’ve gotten readings between 102 and 118 first thing in the morning. Never under 100. What do you think’s going on? Thanks

  2. I have been having high blood sugars on and off with epigastric pain. During one episode my pancreatic enzymes were high and in another episode my liver enzymes were high. My blood sugar has consistently been high fasting for the past 8 weeks… anywhere between 120 and 136.Sometimes it is 160 two hours after eating, but not always….sometimes it goes to below fasting levels. My A1-C is 5.3. I am a fitness instructor and eat a clean diet as I have Celiac Disease . I avoid any type of grain and most processed foods. My dr. just suggested that I eat 1200 calories per day, I do not agree with that as I teach first grade all day and most nights I teach two high impact fitness classes. She also suggested that I exercise more…simply because she didn’t listen to the fact that I teach fitness classes. Any suggestions? I wonder if it is auto-immune . I have Celiac and was heading toward Hashimotos.

  3. I just had a blood sugar test at a health fair. I did not fast. I had a small protein shake and a peanut butter cookie for breakfast and the blood test was one hour later. It was 46. I have no bad symptoms and pretty much unlimited energy. Should I be worried. (I workout and eat small meals throughout the day).

    Andi

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