The bigger picture - how does blood sugar control fit into metabolic health and longevity?

To really make the most of your blood sugar data you need to understand what it’s telling you about your metabolic health and where this fits into the bigger picture of actually living more healthy years.

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Written by
Dr Alasdair Scott MBBS FRCS PhD

gut doctor, PhD and our research director

Published
Key Takeaways
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    Most of us will die from heart disease, cancer, diabetes, dementia or stroke.

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    Metabolic health describes how your genes, your lifestyle and even your gut microbiome interact to influence your risk of these diseases.

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    Only 1-in-10 of us has good metabolic health.

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    Blood sugar control can be used to assess your metabolic health before you develop signs of metabolic disease.

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    A continuous glucose monitor is an ideal tool to measure your blood sugar control.

Your blood sugar is just a number. An important number for sure but it’s not the be all and end all. Our goal at Selph is to help you live more healthy years. That’s the be all and end all. That’s what really matters. So the question is, what is your blood glucose control telling us about your metabolic health and how does it affect your likelihood of living more years in better health?

To answer this, we need to take a step back and look at the bigger picture of metabolic health and how it affects health and disease overall.

What is metabolic health?

“Metabolic health” describes how your genes, your environment and your gut microbiome interact to cause the major diseases of ageing. Let’s unpack this a little.

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Metabolic health describes how your genes, your environment and your gut microbiome interact to cause the major diseases of ageing.

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Your genes are what make you, you, rather than me. They’re DNA sequences that tell your body what proteins to make. Chief amongst these proteins are your enzymes. These are the catalysts that make most of the chemical reactions in your body happen. I say most and not all because a large proportion of the reactions happening in your body are aided not by your enzymes, but by enzymes produced by your gut bacteria or microbiome. Lastly, when we talk about your “environment” we’re not literally talking about your surroundings but rather what you expose your body to. This includes everything from diet, exercise and air to stress, sleep and supplements.

Each of these three factors - genes, environment and microbiome - combine to influence the chemical reactions in your body (your metabolism) and ultimately it’s these reactions that are responsible for driving chronic disease as you age.

We’re probably guilty of taking metabolic health for granted. It’s the unsung hero that sits in the background and actually makes our bodies work. In terms of media hype you’d think gut health is where it’s at. However, I don’t think many pensioners in their last decade are ruing the fact that they didn’t pay more attention to their gut health. No, they wish they were fitter, stronger, didn’t have diabetes or heart disease and hadn’t had a stroke. In short, they wished they had better metabolic health.

Why does metabolic health matter?

On the one hand, ageing is a natural part of the human experience. On the other hand, you can view ageing as a collection of diseases that build up over time. Diabetes, heart disease, stroke, cancer, dementia, frailty and falls. These are the diseases that define ageing. This is how you will (most likely) die. And metabolic health is at the root of them all.

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Diabetes, heart disease, stroke, cancer, dementia, frailty and falls. These are the diseases that define ageing. This is how you will (most likely) die.

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A sedentary lifestyle, excess energy intake, ultra-processed foods, genetic bad-luck, a maladapted microbiome and a host of other factors combine over time to produce a common cluster of features known as the metabolic syndrome.

You have metabolic syndrome if you have any 3 of the following 5 criteria:

What is metabolic syndrome?

If you have any 3 of the following, you have metabolic syndrome.

  • Waist circumference ≥ 102cm in males and ≥ 88cm in females
  • Triglyceride levels ≥1.7 mmol/L
  • HDL cholesterol <1.03 in men or <1.3 in women
  • Elevated blood pressure ≥ 120 systolic, ≥ 80 diastolic or on treatment for high blood pressure
  • High fasting blood glucose, ≥ 5.6mmol/L and high HbA1c ≥ 39mmol/mol

A large study in 2019 found that 90% of American adults had one or more of these criteria so only 10% could be considered “metabolically healthy”1. Individuals with metabolic syndrome (3 or more criteria) have a 24% increased risk of death from any cause and a 44% increased risk of death from heart disease2. They’re also at higher risk of cancer3, dementia4 and stroke5. What’s more, many of these studies found you didn’t need three of these factors for your risk to start increasing. Just one factor is enough to increase your risk and your risk increases step-by-step with each additional factor.

Poor blood sugar control is the “smoking gun” of metabolic disease

Heart disease, diabetes, stroke, cancer, dementia - none of these conditions happen overnight. They all take decades to develop. Insulin resistance, or the reduction in your body’s ability to respond to glucose, is the “smoking gun” that sets it all off. What’s more, insulin resistance can start early, in your teens and twenties. As we’ve discussed in another article, insulin resistance drives fat accumulation in your organs which sets off a chain of events resulting in metabolic syndrome.

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Heart disease, diabetes, stroke, cancer, dementia - none of these conditions happen overnight. Insulin resistance is the "smoking gun" that sets it all off.

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If we want to live more healthy years, we need to be able to answer the question, “is my metabolic health good”? If you’ve got one of the five factors of metabolic syndrome listed above then the answer is easy - “no”. But you shouldn’t have to wait until you’ve got a problem that’s already increasing your risk before taking action. How do you assess your metabolic health before you get metabolic syndrome?

This is where blood sugar control comes in. Because insulin resistance is the driver of metabolic syndrome, we can use blood sugar control as the barometer of our metabolic health. Poor glucose control is a sign of poor metabolic health well before you get to metabolic syndrome.

How you should really use a CGM to optimise your longevity

You’ll remember from our article on insulin resistance that in the early stages, your fasting and average blood glucose levels will often be normal because your body is able to compensate for insulin resistance by producing more insulin. You’ll probably have a normal fasting glucose and HbA1c level.

To see the signs of insulin resistance we need to look at your glucose control when your metabolism is stretched a little. A continuous glucose monitor (CGM) allows you to see your blood glucose levels (well, a very good approximation) over time. Specifically, you can see how your blood glucose changes in response to a metabolic stressor - i.e. food.

Over time, you can build up a picture of your blood sugar control and insulin sensitivity. How high are your peaks and how often are you having them? What’s your average blood sugar and how much variability is there (peaks and troughs)? How quickly can your body dispose of a glucose load?

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The real value of a CGM is that it can be used to assess your metabolic health.

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The real value of a CGM is that it can be used to assess your metabolic health. It’s not about trying to figure out which foods you should or should not eat. If you eat a piece of cake and have a high, sustained glucose response you have NOT learned that you shouldn’t eat cake! You know this already! You’ve learned that your body is not metabolically healthy enough to dispose of a glucose load. This is what you need to fix! Yes, food is a part of this fix, but that’s at the macro, sustained level of your overall diet rather than being overly concerned with glucose responses to specific foods. An athlete can eat cake without a high, prolonged glucose spike but you can’t. That’s not because all athletes have special cake disposing genes, it’s because they’re more metabolically healthy than you.

So use a CGM as a tool to help you assess your metabolic health. When you understand where you are in terms of metabolic health then make a plan to improve it. Take 3 to 6 months to optimise your diet, exercise, sleep, stress and so on. Then make another assessment with a CGM. Where are you now? Are things moving in the right direction? Do you need to course correct? How can you become even more insulin sensitive? This is how to use a CGM as a tool to optimise your health for longevity.

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