Monday, July 28, 2008

Reactive Hypoglycemia


When we think about blood glucose, we usually think about hyperglycemia, or excess blood glucose. But sometimes we can have too little glucose in our blood. The symptoms are lightheadedness, anxiety, and hunger. Low glucose can even produce shakiness and heart palpitations. This post discusses one of the causes of low blood glucose, reactive hypoglycemia.

Reactive hypoglycemia is important because it can be one of the steps on the path to type 2 diabetes. It is one of the possible responses to a six-hour glucose tolerance test, illustrated in the graph above. The normal person, represented by the red line, has ingested a large bolus of glucose at zero hours. The beta cells of his pancreas have released the appropriate amount of insulin, and while the amount of glucose in his blood has spiked a little, within 2.5 to 3 hours it has come back into the normal range of 70-110 mg/dl, which corresponds to a value between 4 and 6 mmol/L on the graph above. Once the extra glucose has been safely stored, insulin levels decline and the liver takes over.

As discussed in the previous post, the liver can release its stored glycogen in the the form of glucose, and it can also make glucose by gluconeogenesis. Between meals, the liver uses these two processes to keep blood glucose in the range between 70-100 mg/dl or 4-6 mmol/L.

After a person eats carbohydrates, his liver shuts down its production of glucose via glycogenolysis and gluconeogenesis. That makes sense. If the person is ingesting glucose, why would he want to add more glucose to that amount?

When a person eats protein, the situation is a little different. Insulin must be released to store the amino acids building blocks of the protein. But insulin is nonspecific. As it promotes the storage of amino acids, it will also drive glucose from the blood. Without some compensatory mechanism, the process of storing the amino acids would also produce severe hypoglycemia. In steps the pancreas. This time the alpha cells of the pancreas release the hormone glucagon. Glucagon tells the liver to release some of its glycogen in the form of glucose. The liver also begins to do gluconeogenesis to make more glucose. Thanks to the liver, glucose levels can be maintained while insulin is busy telling the body to store its new supply of amino acids. Once the nutrients are stored, the liver goes back to its baseline functions and enables the blood sugar to continue in its normal range.

So far, so good. But as diabetes develops, the liver is one of the organs that becomes insulin resistant. When the liver becomes insulin resistant, its production of glucose becomes dysregulated. The liver can no longer turn off its glucose output in response to carbs, or regulate its glucose output properly in response to protein.

Think about that. The person with insulin resistance may not be eating carbs, but his liver is making carbs (that is, glucose) all the time. In order to control the resultant high blood sugar, the pancreas must produce more insulin. That will get the blood sugar down in the short term, but in the long term it will make the liver more insulin resistant. Eventually, still more unwanted glucose will be produced by the liver, and even more insulin will need to be released by the pancreas.

In the process, the pancreas itself starts to suffer insulin resistance. It releases insulin erratically. Sometimes it allows the blood sugar to go too high. At other times the pancreas overshoots the required amount of insulin and the blood sugar drops too low. This leads to the phenomenon called reactive hypoglycemia, which is shown in the black line in the graph above. The person represented by the black line has ingested a large amount of glucose, but his pancreas has responded by releasing too much insulin, and his blood glucose has fallen below the normal range. Over time, reactive hypoglycemia can eventually progress and intensify to the condition of the person represented by the brown line, which is prediabetes.

We tend to think of type 2 diabetes as a condition characterized by high blood sugar. It is, but for many people, one of the steps on the road to type 2 diabetes is actually low blood sugar. If a person is not a diabetic but is experiencing episodes of low blood sugar, it might be time for him to consult a physician. It could be a important warning sign and an indication that he might need to make some changes in his lifestyle.

The figure is from the Hypoglycemic Health Association of Australia.

10 comments:

Helen said...

Hi Stargazey... sorry for another question. If someone has reactive hypoglycaemia, does that mean even if they go on a low carb diet, the liver make glucose from the protein they eat? Is there a way out of this cycle? Thanks again!

Stargazey said...

Yes, for people who eat a very low carb diet, a large percentage of their blood glucose actually comes from the protein they eat. Most people self-limit the amount of protein they consume in a day, but here is a Handy Guide to calculating the number of grams of protein you need each day. It takes into account the amount of protein you need both for tissue repair and for the gluconeogenesis required to maintain a proper blood glucose level while following a low-carb lifestyle.

If you have reactive hypoglycemia, it's important to keep the release of insulin as low as possible to restore the insulin sensitivity of your tissues. That would mean keeping carbs very low, limiting protein to the calculated daily protein requirement and making up the caloric difference with healthy fat. It would also mean eating about three meals a day, with 5-6 hours between each meal, to allow insulin levels to return to baseline between each meal.

Do bear in mind, however, that I'm not a physician, so I'm speaking from a theoretical perspective, not a clinical one. What works in real life is sometimes different from what works in theory, so be sure to consult with your doctor to see what suggestions he/she might have about this approach.

Helen said...

Hi
You don't need to post this, I jsut wanted to say a really big thank you for taking the time to answer questions so well.

The link was great.

Cheers

Stargazey said...

Thanks, Helen! It is a very helpful link, isn't it? I'll go ahead and post your comment, just to let people know that I'm glad to answer questions. It means people are interested and are thinking about what I've said. If something isn't clear (and in science that is often the case), I'll try to do my best to explain it.

WoodsWalker said...

Hi Stargazey,

Well, here's another very helpful post. This information supports why I became interested in low-carb diets in the first place. It all goes back to when I was worked for the local diabetes association. We used to try out the demo blood glucose meters (what a party!). After a lunch with a lot of bread, I had no trouble getting a reading of 11 mmol (I am in Canada where we measure in millimols, just like the scientists do!). I was 30 and not overweight (I am now somewhat older and still not overweight). I find now that I increasingly feel groggy and unwell after consuming too much carbohydrate, and conversely bleak and shaky if I don't eat for just a little too long. Any time I've gotten a standard mid-morning blood test the blood glucose has been fine.

Although I'm not overweight, my reasons for interest in low-carbing are simply: 1) to feel better, and 2) to have some respect for a family history of diabetes, and for these little indications that I may take after my ancestors.

Thanks for an informative post and, once again, a great illustration!

~Wendy

Alex said...

Thanks for this post Stargazey,

I know this is a little late relative to the original post, but this really hits home for me.

I have had reactive hypoglycemia for years and was hoping it would be resolved with a traditional low-carb (Atkins, Protein Power...) diet.

I have lost weight and my health is vastly improved, but until recently my hypo symptoms have not improved. I recently had realized that I was simply eating too much protein and my body was apparently releasing too much insulin in response.

It was really hard to figure out and it took a lot of experimentation to get there, but now I have a good sense of how to make some progress on my symptoms.

I really like your advice of waiting 5-6 hours between meals to insure that insulin levels fall from post-prandial levels. I think this explains why I am still getting afternoon symptoms about 4 hours after lunch. I eat breakfast around 7:30 and lunch at 11:30. I plan to try experimenting with eating my lunch later or breakfast earlier to give the insulin levels longer to fall before I get to lunch.

Thanks for the insight. I know you're not offering medical advice here, but neither has my doctor. It's sad that so many doctor's seem to have so little clue about hypoglycemia. My doctor's last advice, despite the fact that I told her it wasn't working, was to continue eating many small meals.
When I told her that the problems only seemed to happen shortly or immediately after eating, she said "that's interesting" and insisted on her existing advice.

I'm glad I didn't listen to my doctor this time.

My saving grace has definitely been fat consumption to make up the calories I need and figuring out how many grams of protein I can tolerate per meal. My threshold seems to be about 30g(+/- 5g) per meal.

Cheers,
Alex
Low Carb New England

Stargazey said...

Your story is very interesting, Alex. And your comments certainly aren't "late" because reactive hypoglycemia is such a significant problem for many people.

I'd be very interested to learn whether your strategy of continuing to do low-carb, but eating less protein and increasing the time between meals has any effect on improving your insulin sensitivity and decreasing your reactive hypoglycemia. I would guess that it will take weeks to months to see a difference, but if it happens, that would be an important finding. And if it doesn't happen, that would be important, too. It would indicate that we need to take other factors into account as well. Please come back and keep us posted.

Simon said...

Someone should start a site with general information about LowCarbHighFat in English. The diet is getting really big in sweden and there is a sort or small revolotion going on.

But i dont see the same anywhere else. But this diet has a historic potential.

Is there anay general information site in English?

Stargazey said...

Hi, Simon! I'm sorry it took me so long to respond to your question. When someone makes a comment on Blogger, it doesn't tell the blog-owner which post the comment is under. So I had to wait for Google to tell me where yours was! (Not your fault, by the way--just a quirk of the software.)

Actually, low-carb, high-fat is a good description of the original Atkins Diet. It wasn't until later in his life that Dr. Atkins added all the products and extra carbs. And sadly, the current Atkins company has strayed very far from the low-carb, high-fat philosophy.

There are many low-carb sites in English. Dr. Michael Eades' blog is a good place to start. Click on the links in his Blogroll and you will find more sites. Each one has a different emphasis, but I'm sure you'll find one you like. (As far as the high-fat part, true low-carbers figure out that they also have to do high-fat, but they generally don't advertise it too much because people are so indoctrinated that fat is bad for you.)

As far as the Swedish low-carb, high-fat movement, I'm actually planning to do my next post on it. Thanks for the inspiration!

Hanna Stocksick said...

I have reactive hypoglycemia, and what really changed my life, what set me free from eating and crashing was Dr Jack Kruse tips given at his website: eat at least 50 g of protein for breakfast, no bad carbs such potatoes, rice, and bread, and keep your carb intake to the minimum at dinner. It was like miracle to me! I could finally eat only 3 meals a day and have no cravings at all. Those that suffer from hypoglycemia know what I mean!
www.jackkruse.com