January 21, 2011

Slow Digestion Can Explain Odd Readings

I received emails this week from three different correspondents that asked about strange blood sugar readings several hours after eating. In my replies I mentioned slowed digestion as a possible cause. As I did so I realized this is a blood-sugar related problem that isn't often discussed in mainstream media, so it isn't familiar to all of us.

I first learned about it in reading Dr. Bernstein's landmark book,Dr. Bernstein's Diabetes Solution. Bernstein explains that delayed digestions, which he calls by its medical name, gastroparesis, results when neuropathy affects the nerves of the autonomic nervous system that control the opening and closing of the valve at the bottom of the stomach.

If the valve stays shut after eating, your food does not get to the upper part of the gut where much of it digests. As a result, starch and complex sugars don't turn into glucose and your blood sugar stays low after eating. Eventually, of course, the valve does open, and when it does your food digests and your blood sugar rises.

If you aren't using insulin, this merely will give you odd readings. You'll see good readings an hour or two after eating, only to discover your blood sugar soaring the third hour.

However, if you use fast-acting insulin at meals this effect can be dangerous, because your insulin will peak at about an hour after you eat whether or not your blood sugar is high. If you inject enough insulin at the time you eat to cover a significant amount of carbohydrate, you may end up with a hypo if that carbohydrate doesn't digest into glucose in time to meet the insulin.

And even if you don't hypo, if digestion is delayed, by the time your food does digest you may not have any insulin left to cover it, so you will end up with a very high blood sugar.

Delayed stomach emptying can be very hard to deal with because there may be no pattern to how the valve behaves. It may open at different intervals after every meal. Fast one meal, very slow the next. You may eat lunch and not have it digest until you eat your dinner.

Dr. Bernstein's book contains a long section that lists various treatments he's found helpful when treating patients with the slow stomach emptying that results from autonomic diabetic neuropathy. It's well worth reading if you suffer from this problem.

Since the autonomic neuropathy that causes delayed stomach emptying is a late diabetic complication that occurs only after long exposure to very high blood sugars, most of the people with Type 2 diabetes who are reading this blog because they are devoted to keeping their blood sugar normal aren't likely to experience it.

But--and Dr. Bernstein does not discuss this--there are other conditions besides autonomic diabetic neuropathy that can also cause delayed stomach emptying. So slowed digestion does occur in otherwise healthy people with normal blood sugars.

A friend of mine experienced this problem--confirmed by gastroscopy--after suffering a severe bout of stomach flu. It lasted for more than five years until for no discernible reason it finally went away.

People who have other medical conditions that affect the functioning of their nerves or muscles may also experience this phenomenon, regardless of their blood sugar status. It may also come on with age, when the digestion seems to slow down for many people. It may even be a response to the inflammatory reactions associated with conditions like gluten sensitivity.

This is why some people with diabetes who have kept good control over of their blood sugars or who are recently diagnosed will still see readings that don't make sense to them. Delayed stomach emptying keeps their blood sugar from peaking at the average time--75 minutes after eating--and they see surprise blood sugar highs at some other time, anywhere from one to four hours after eating.

If this is your pattern, especially if it occurs in an unpredictable manner, you will have to be extremely careful when injecting insulin to cover a meal. If your meal delay is predictable--for example, if you always see a peak after eating at two hours rather than one, you can just inject your insulin an hour later. But if it isn't predictable, using insulin according to some "one size fits all" dose schedule your doctor handed you may become dangerous.

One helpful rule to use when dealing with this problem--one that is a lot easier to follow if you are eating a relatively low amount of carbohydrates--is to never inject more insulin before a meal than your body could handle even if there was no food coming in at all. This may not be enough to fully cover the meal, but if you don't know when your meal will digest, it's better to shoot less than too much. Then, an hour after you eat, test your blood sugar, and based on what you see then, inject an additional corrective dose.

Never injecting more insulin than you can handle on an empty stomach is a good practice to follow even if you don't have stomach issues, because things sometimes come up that keep you from eating a meal, after you've injected--like a sudden attack of vomiting or a family emergency. So it's never a good idea to inject more insulin than your body can handle without a lot of carbs in it.

However, in order to use this kind of strategy where you inject partial doses and calculate a correction dose, you will have to have a very good understanding of how to match insulin to carbohydrates. If you are injecting the same amount for each meal because that's what you were taught by the "diabetes nurse" at your doctor's practice, you need to get yourself some more education before you try it.

A good place to start is to read Dr. Bernstein's book or John Walsh's Using Insulin.If you don't understand how to match your insulin dose to what you ate after reading up on the subject, don't guess. Demand that your doctor hook you up with someone who can explain it properly. The combination of poorly calculated or generic insulin doses and unpredictable stomach emptying is dangerous and may be one erason why so many older people with diabetes end up with hypos that put them in the hospital.

Many people with Type 2 can avoid having to use insulin at meals if they cut back on their carbohydrate intake enough. If you haven't tried a lowered carb diet you might be surprised how well it works. The strategy described HERE can help you find out just how low you need to go to see results. An intake somewhere near 100 grams a day or 30 grams a meal is very helpful to many people with diabetes without being so low that they find it onerous to stick to it.

Cutting out all products containing gluten is worth a try, too, because so many people find that persistent digestive problems clear up when they do this.

However, if you jump on the currently fashionable gluten-free bandwagon, take care. I'm seeing a disturbing trend, now that this way of eating has become mainstream. The "health food" groceries are filling up with "gluten free" products that are extremely high in carbohydrates, which are being promoted as if they were good for you. They aren't. They are just expensive blood sugar bombs, filled with fast, refined carbs, both starches and sugars. They are a poor choice for anyone who is interested in preserving their health, and for people with diabetes they are dangerous since the high starch and sugar content is guaranteed to raise blood sugar very high.

Have you had experience with delayed stomach emptying? Any tips for dealing with it? Post them in the comments section if you do.


homertobias said...

Enteric coated peppermint is a natural smooth muscle relaxant used widely for IBS dysmotility syndromes.
Yes it usually is enteric coated. Usually because it can cause relaxation of the GE junction and make GERD worse. So don't try it if you have GERD.
If not, try enteric coated or maybe nonenteric coated peppermint.
Maybe peppermint tea.

homertobias said...

Or maybe digestive bitters.

Sysy Morales said...

First of all, this is an excellent post. Secondly, I think I've dealt with this. I have managed, after reading Dr. Bernstein's book, to figure out what works for me.

I have minimized carbs and omitted any processed foods. The only grain I eat is ezekial brand toast. (It keeps my digestion moving where as any other grain stops it)

I hardly intake any dairy. I just have whole fruits and vegetables (way more vegetables than fruits) and I eat nuts, organic chicken and beef and lamb.

I've found that sticking to the above diet keeps my blood sugars predictable and level. I find that just one slice of pizza will cause high blood sugars for hours after eating-and just as you discribed, sometimes I get low after eating and then high.

For me it's clear what I have to do to maintain my digestion working properly so I do it. I wish I had heard about Dr. Bernstein's book sooner-before I was in the hospital from intestinal blockage.

Thanks for this comprehensive post!

Retha said...

A lot of the recipes on http://lowcarbdiets.about.com
are gluten free because Laura Dolson is gluten intolerant

PJNOIR said...

my numbers drop dramatically in the third hour and are never good after two. I wonder if this is a version of slow digestion?

Steve Parker, M.D. said...

Good article, Jenny.

Another cause of delayed digestion I see commonly is narcotic usage, including Percocet, Vicodin, Roxicodone, Dilaudid, etc.

It's something to consider for people with diabetes taking narcotics intermittently and unpredictably.


Jenny said...

Dr. Parker,

A good point. I just remembered an interesting book I read, The Second Brain, which discusses the gastro-intestinal nervous system. It made the point that SSRIs can also affect digestion. Given how over-prescribed these drugs are, I wouldn't be surprised if they, too, were a cause of slowed digestion.

Steve Ollis said...

I've recently been diagnosed with Type 2 Diabetes, and found that the following article helped me to understand what my Dr was telling me to do. Now for the nutrionist appointment.

Jenny said...

Steve, The link you pointed to is the usual advice given to people with diabetes. There's only one problem. It isn't really true.

After you hear from the nutritionist, do yourself a favor and try the technique described HERE.

It will show you what is raising your blood sugar. Once you know that, you can eliminate those foods or cut back on them until your blood sugar is normal.

All too often the standard advice is based on theories and research conducted on rodents whose metabolisms and tolerance for fats is very different from that of humans. And the quality of nutrition studies conducted on humans is so poor that it wouldn't be considered science by people in other scientific disciplines.

Jin said...

My doctor told me that low thyroid can contribute to slow peristalsis.

lizz.starr92 said...

I'm really liking your comment about Gluten-free foods! I have always thought that they are nothing but over-processed carbs which are likely to have little nutritional value. Okay so that maybe a little extreme but its good to see other people realise they're not so good for you.
I am coeliac and also diabetic, the coeliac disease came first.. I'm diet controlled and I find these foods do not agree with my blood sugars at every meal. I have to restrict them to once a day at a meal.

Sand_Al said...

Hi Jennie, you had mentioned the issue of delayed digestion to me in a post I'd made regarding 1st and 2nd phase blood sugar readings. (My 2nd phase, was at times higher than the 1st phase.) Since reading your response, I've been experimenting with digestive enzymes (I'm in the prediabetic range and not a diagnosed diabetic on insulin)because I wanted to see what impact the enzymes might have on my digestion, and therefore, my readings. In the past 24 hours, my readings have definitely changed. My first phase is now slightly higher than my second phase. It averages out to almost a 15 point difference now, with the second phase being consistently lower. I don't know if my experiment really is valid, but I'm liking the trend and will continue documenting using the enzymes to see if the pattern holds. I wouldn't have thought to do this without your earlier feedback. Thank you!