Normal blood sugar begins in the gut

Maintaining normal blood sugar levels is an important component of health. In both type 1 and type 2 diabetes, the ability to control blood glucose goes out the window. In these conditions, it’s an impairment of insulin secretion or insulin sensitivity.

But this is a rather myopic view of blood glucose regulation. There’s another important player called glucagon that doesn’t get enough dap. Furthermore, there are major upstream players made in the gut that regulate both glucagon and insulin.

In today’s blog, we’ll discuss how insulin and glucagon maintain normal blood sugar and the important hormones in our gut that regulate both. We’ll also cover how we can use these gut hormones to our advantage without completely cutting out carbohydrates from our diet.

How insulin and glucagon maintain normal blood sugar

The pancreas secretes both insulin and glucagon in response to changes in blood glucose. They are considered counter-regulatory hormones: Hormones that work together through opposing means.

When our blood glucose begins to rise, beta cells in the pancreas sense this and secrete the hormone insulin. Insulin enters the blood and causes specific tissues in the body such as muscle and adipose tissue to take in excess glucose. The result: blood glucose decreases.

When our blood glucose begins to drop, alpha cells in the pancreas sense this and secrete the hormone glucagon. Glucagon then enters the bloodstream and makes its way to the liver. In response, the liver breaks down glycogen, the storage form of glucose, and releases it in to the blood. The result: blood glucose rises.

This dance between insulin and glucagon goes on through periods of feasting and fasting, as well as periods of inactivity and activity, to maintain our blood glucose in a very narrow range. In a healthy person, this leads to a balance where high insulin normally means low glucagon, and vice versa.

In those with Type 2 diabetes, the entire system is screwy. Both insulin and glucagon are high, and this causes the system to break down. The result: a blood sugar rollercoaster.

How our behavior maintains normal blood sugar

Hormones aside, our lifestyle also plays an important role in regulating blood glucose. When we eat, we break down our food and absorb it. We convert carbohydrates from our food into glucose and absorb it into our blood.

It’s important to point out that carbohydrates from whole foods increase blood glucose more slowly than from processed foods. Whole foods take time to digest and absorb, so they take time to appear in the blood. But food processing is essentially a form of pre-digestion, so processed foods like bread lead to a more rapid blood glucose response than something like a potato.

We also convert certain amino acids from protein called glucogenic amino acids into glucose. But, for the most part, carbohydrates are the primary dietary contributor to our blood glucose. This is why a lower carbohydrate diet can help improve high postmeal blood glucose responses.

Physical activity patterns are also important. When physically active, our muscles act like a glucose sink. In fact, exercising muscle can pull glucose out of the blood without the help of insulin. This is why being active after meals can help limit a person’s glucose peak from that meal. In addition, one of the responses to long term exercise is an increase in the ability of muscles to store glucose as glycogen.

Finally, we convert any excess glucose to fat through a process called de novo lipogenesis. This primarily occurs in adipose tissue and the liver, and our ability to perform it depends on our genetic limit to store fat and how close we are to that limit. The closer you are to your fat storage limit, the longer excess glucose will circulate with nowhere to go.

The gut and blood glucose regulation

As you can tell, both behavior and hormones play an important role in blood glucose regulation. Being more physically active and consuming an appropriate amount of carbohydrates are viable options to improve blood glucose. But what is appropriate can vary widely between individuals based on genes and lifestyle.

Furthermore, optimizing hormonal balance is essential to healthy blood glucose regulation. However, you don’t need to follow a low carbohydrate diet to optimize this hormonal balance. It is one way of managing your blood glucose levels better. But it’s often implied that low carb diets are better because they promote metabolic flexibility.

This simply isn’t true. A perfectly healthy person should have no problem consuming carbohydrates and maintaining normal blood glucose levels. Type 2 diabetics can’t because they’re insulin resistant and glucagon is elevated. As a result, they’ll fail an oral glucose tolerance test.

Removing carbohydrate doesn’t fix this problem, at least no more than losing weight via any method will. Part of this issue is driven by dysfunction in another set of hormones made in the gut called incretins. Incretins are hormones made in the gut that help manage blood glucose by regulating insulin and glucagon.

Meet the incretins

Incretins are gut-derived hormones that regulate our blood glucose response to meals by regulating insulin and glucagon. Glucagon-like peptide 1(GLP-1) is one of these incretin hormones. GLP-1 increases when we eat, which enhances insulin secretion AND blocks glucagon secretion at higher glucose levels. In essence, it prevents hyperglycemia. It also plays a role in regulating appetite.

Gastric inhibitory peptide(GIP) is another incretin hormone that increases when we eat. GIP primarily increases insulin, so it lowers blood glucose too. Though, it does have some role in glucagon secretion as well. To date, there is no evidence GIP plays a role in regulating appetite.

In a healthy person, incretins contribute 50-70% of the insulin response to meals. People with Type 2 diabetes experience incretin dysfunction. As a result, incretins only contribute 20-35% to postmeal insulin response.

Now, as you may be able to tell, eating a lower carbohydrate diet will lead to lower blood glucose levels. But this is more akin to symptom management than actually solving the problem. The problem isn’t that your blood glucose levels skyrocket after meals, it’s that you’re not managing your blood glucose levels properly when challenged.

You can clearly see this by performing an oral glucose tolerance test during a low carb/keto diet. You’ll fail this test hands down, but that’s not because you’ve damaged yourself. It’s because your body has adapted to a lower carbohydrate intake which requires less insulin and, therefore, requires less of an incretin effect.

This doesn’t mean that you shouldn’t do a ketogenic diet. It means that if you’re keto, stay keto. And if you want to consume a higher carbohydrate diet, it’s certainly an option provided you have your incretins in order. This may take time, it won’t happen overnight.

Tips to enhance the incretin effect for normal blood sugar

There are a number of things you can do to enhance the incretin effect or, alternatively, prevent it from sucking. First and foremost, incretins are under circadian control, so all the wonderful things that strengthen circadian rhythms are important. The microbiome may be a key player here.

Second, meal order also seems to have an effect. Consuming your protein or fat source prior to your carbohydrate source leads to a better incretin response than eating carbohydrates first. Eating fiber first also leads to a better glycemic response to meals. So eat your meat and salad first, and attack those starches after.

Being physically active is also important. In addition to freeing up space for excess glucose to go, regular exercise seems to enhance the incretin effect. And it doesn’t require running a marathon either; just walk more and be more active in your hobbies.

Finally, including more fiber in your diet may increase the incretin effect by increasing short chain fatty acids(SCFAs). One paper found that consuming wheat fiber improved the incretin effect over 1 year in type 2 diabetics, likely through SCFA production. A review on the topic shows that increased fiber consumption consistently increases the incretin effect over the long term.

SCFAs increase GLP-1 release in the gut. But keep in mind this takes time, so you want to increase fiber first, then slowly increase carbohydrate intake. Not only do you need to eat fiber, you have to develop a microbiome that ferments fiber. If you are type 2 diabetic or coming from a low fiber diet, that will take time.

In addition to being important for those with type 2 diabetes, being cognizant of the incretin effect is useful for transitioning out of a ketogenic diet if that’s something you want to do.


When it comes to maintaining normal blood glucose levels, there’s more than one way to skin a cat. Most people focus on insulin, but it’s counter-regulatory sister glucagon is also important. Furthermore, the incretin hormones secreted from our gut when we eat control both of these hormones.

What we choose to eat, our activity levels, and circadian rhythms all play an important role in regulating incretin hormones. Unfortunately, by focusing too much on insulin, most people just say screw it and go on a low carbohydrate diet. If you look at blood glucose regulation from strictly an insulin perspective, a low carbohydrate diet seems like the best practice.

Fortunately for carb lovers, it’s a little more complicated than that. By looking at the incretin effect upstream from insulin and glucagon, many more options enter the picture. So if you want to eat carbs, you can eat carbs. If you prefer keto, there’s nothing wrong with staying keto either.

Ultimately, adherence is the most important factor, as well as maintaining a healthy bodyweight. And if you want to go keto for a time to lose weight and then transition to a higher carbohydrate diet, take note of the incretin effect and use it to your advantage.

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