Gastroparesis: Diagnosing

from Dr. Bernstein’s book “Diabetes Solution”
© 2007 by Richard K. Bernstein, M.D.

Efforts at diagnosis are usually unnecessary if there is no reason to suspect the presence of gastroparesis. So first we must have an index of suspicion. If, at the initial history-taking interview with your physician, you mention symptoms like those described earlier in this chapter, he should have a high index of suspicion. If your R-R interval study (Chapter 2) at the initial physical exam is grossly abnormal, he can be quite certain of gastroparesis. Remember that this study checks the ability of the vagus nerve to regulate heart rate. If the nerve fibers going to the heart are impaired, the branches that activate the stomach are probably also impaired. In my experience, the correlation of grossly abnormal R-R studies with demonstrable gastroparesis is very real.*

Diagnostic Tests
Given the physical symptoms or the abnormal R-R study, your physician may want to consider further tests to evaluate your condition.  The most sophisticated of these studies is the gamma-ray technetium scan. This test is performed at many medical centers, and is quite costly. It works this way: You eat some scrambled eggs to which a minute amount of radioactive technetium has been added. A gammaray camera trained on your abdomen measures (from outside your body) the low levels of radiation the technetium emits as the eggs pass from your stomach into your small intestine. If the gamma radiation drops off rapidly, the study is considered normal.

A less precise study can be performed at much lower cost by any radiologist. This is called the barium hamburger test. In this test, you eat a ½ pound hamburger and then drink a liquid that contains the heavy element barium. Every half hour or so, an X-ray photo is taken of your stomach. Since the barium shows up in these photos, the radiologist can estimate what percent of the barium remains in your stomach at the end of each time period. Total emptying within 3 hours or less is usually considered normal.

Despite their theoretical usefulness, neither of these studies is anywhere near 100 percent sensitive, because of the unpredictable nature of the paretic stomach. One day it may empty normally, another day it may be a bit slow, and on yet another day its emptying may be severely delayed. Because of this unpredictability factor, the study may have to be repeated a number of times before a diagnosis can be made. The possibility exists that you could have several normal studies but still have abnormal stomach-emptying. I therefore advise my patients against using either of these two tests. The R-R study is my gold standard.

Telltale Blood Sugar Patterns
Having medical tests is bad enough, but having to repeat them with conflicting results naturally proved quite annoying to my patients many years ago when I actually repeated them. Worse than annoyance, the studies are not cheap, and most insurance companies will not pay for repeats of the same study unless they’re separated by many months. If you’re regularly measuring your blood sugar levels and trying to keep them in the normal range, it’s really not difficult to spot gastroparesis that’s severe enough to affect blood sugars. For practical purposes, this is just the degree of gastroparesis that should concern us.

Below are some of the typical blood sugar patterns that I look for. To call these patterns, though, is slightly misleading. The hallmark of gastroparesis is randomness, unpredictability from one day to the next. These “patterns” come and go in such a fashion that blood sugar profiles are rarely similar on 2 or 3 successive days. The first two patterns together are highly indicative of gastroparesis, while the third by itself is usually adequate for diagnosis.

  • Low blood sugar occurring 1–3 hours after meals.
  • Elevated blood sugar occurring 5 or more hours after meals with no other apparent explanation.
  • Significantly higher fasting blood sugars in the morning than at bedtime, especially if supper was finished at least 5 hours before retiring. If bedtime long-acting insulin or ISA is gradually increased in an effort to lower the fasting blood sugars, we may find that the bedtime dose is much higher than the morning dose. On some days fasting blood sugar may still be high, but on other days it may be normal or even too low. We’re thus giving extra bedtime medications to accommodate overnight stomach emptying— but sometimes the stomach doesn’t empty overnight and fasting blood sugars drop too low.

Having seen such patterns of blood sugar, we can then perform a simple experiment to confirm that they really are caused by delayed emptying.

Skip supper and its premeal insulin or ISA one night. When you go to bed, be sure to take your basal (bedtime) insulin or ISA, measure your blood sugar, and then measure your fasting blood sugar the next morning on arising. If, without supper, your blood sugar has dropped or remained unchanged overnight, gastroparesis is the most likely cause of the roller-coaster morning blood sugars.

Repeat this experiment several days later, and again a third time, after another few days. If each experiment results in the same effect, delayed stomach-emptying is virtually certain on one or more of the nights when you had eaten. When you had previously been eating suppers, at least some of the following mornings had shown an overnight rise in blood sugars. Since such rises occurred on nights when you had eaten supper, but not on the nights when you did not eat, the rise must have been caused by food that did not leave your stomach until after you went to bed. Be very cautious when performing this experiment, as you may experience severe hypoglycemia upon arising or during the night. To play it safe, check your blood sugar midway through the night and correct it if it’s below your target.

“False Gastroparesis”
I’ve seen a number of patients whose blood sugar profile or physical symptoms could have been diagnostic of gastroparesis, yet their R-R interval studies were normal or only slightly impaired. These people had delayed stomach-emptying but well-functioning vagus nerves. The conflicting data obliged me to order upper gastrointestinal endoscopic studies for these people. Endoscopy uses a thin, flexible, lighted fiber-optic cable to look directly into the stomach and duodenum.

The endoscopic tests demonstrated that they all had abnormalities unrelated to their diabetes. Such findings have included gastric or duodenal ulcers, erosive gastritis, irritable gastrointestinal tract, hiatal hernia, and other gastrointestinal disorders such as tonic or spastic stomach. Each of these conditions required treatment distinct from treatment for diabetes. Only with hiatal hernias were we unable to at least partially alleviate the digestive problem. In such cases, however, surgical correction of the hiatal hernia is possible, but it may or may not normalize emptying. Blood tests for parietal cell antibodies and serum vitamin B-12 might be performed to rule out autoimmune gastropathy as a cause of gastritis.

The following suggestions for treating gastroparesis may or may not facilitate stomach-emptying for the above conditions but should certainly be tried. The loud and clear message from this is that the R-R interval study should be performed on every diabetic patient whose blood sugar profiles resemble those outlined above.

* If, during an R-R study, your heart rate varies only 28 percent between inhaling and exhaling, then you will likely have mild gastroparesis. If the variation is about 20 percent, gastroparesis will probably be what I call moderate, and if less than 15 percent, I would call it severe.