newer pancreas-provoking OHAs before each meal.
If he were to take hismedication and thenskip the meal, hisbloodsugarwouldplummet.
When thestomach empties tooslowly, it canhave almost thesame effect as skipping a meal.
If we knew when the stomach would empty, we coulddelay the insulin shot or add some NPH insulin to the regular to slowdown its action.
Thebigproblem withgastroparesis, however, is its unpredictability.
We never know when, or how fast, the stomach will empty.
If the pyloric valve is not in spasm, the stomach contents may empty partially within minutes andtotally within 3 hours.
On another occasion, when the valve is tightly closed, the stomach may remain loaded fordays.
Thus, blood sugar may plummet 1-2hours after eating, andthen rise very high, say 12 hours later, after emptying eventually oc curs.
It is this unpredictability that can make blood sugar control im possible ifsignificant gastroparesis isignored inpeople who take insulin (or the type of OHAs I don'trecommend) before meals.
For most type 2 diabetics, fortunately, even symptomatic gastro paresis may not grossly impede blood sugar control, because they may still produce some phase I and phase II insulin.
They therefore may not require significant amounts of injected insulin to cover theirlow- carbohydrate meals.
Much of their insulin is producedin response to blood sugar elevation.
Thus, if the stomach does not empty, only the low basal (fasting) levels of insulin are released, and hypoglycemia does not occur.Of course, the sulfonylurea and similar OHAs (which I don't recommend) can cause hypoglycemia under such circum stances.
If the stomach empties continually but veryslowly, the beta cells of mosttype 2swill produce insulin concurrently.
Sometimes the stomach may empty suddenly, as the pyloric valve relaxes.
This will produce a rapid blood sugar rise, caused bythesudden absorption of carbohydrate following the entrance of stomach contents into the small intestine.
Most beta cells of type 2 patients then cannot counter rapidly enough.
Eventually, however, insulin release catches up and blood sugar drops to normal, if a reasonable regimen is followed.
If your supper doesn't fully leave your stomach before you sleep, you mayawaken with a highmorning bloodsugar due to emptying over night, even though your bedtime blood sugar was low or normal.
In any event, if you do not require insulin or use a sulfonylurea- type OHA before meals, there isnohazard ofhypoglycemia dueto de layed stomach-emptying.
This assumes thatany long-acting insulin or sulfonylurea is administered in doses that cover onlythe fasting state, as discussed in prior chapters.
The traditional use of large doses of
Delayed Stomach-Emptying: Gastroparesis 361
these medications, meant to cover both the fasting and fed states, brings with it the hazard ofpostprandial hypoglycemia when gastro paresis is present.
DIAGNOSING GASTROPARESIS
Efforts at diagnosis are usually unnecessary ifthere isnoreason to sus pect the presence of gastroparesis.
So first we must have an index of suspicion.
If, at the initial history-taking interview with your physi cian, you mention symptoms like those described earlier in this chap ter, he should have a high index of suspicion.
If your R-R interval study (Chapter 2) at the initial physical exam isgrossly abnormal, he can bequite certain ofgastroparesis.
Remember thatthis study checks the ability of the vagus nerve to regulate heartrate.
If the nerve fibers goingto the heart are impaired, the branches that activate the stomach are probably also impaired.
Inmy experience, the correlation ofgrossly abnormal R-R studies with demonstrable gastroparesis isvery real.*
Diagnostic Tests Given the physical symptoms or the abnormal R-R study, your physi cian may want to consider further tests to evaluate your condition.
The most sophisticated of these studies isthegamma-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 amountof radioactive technetium has been added.
Agamma- ray camera trained on your abdomen measures (from outside your body) thelow levels ofradiation thetechnetium emits astheeggs pass from your stomach intoyour small intestine.
If the gamma radiation drops off rapidly, the studyis considered normal.
Aless precise study can beperformed at much lower cost byany ra diologist.
This iscalled thebarium hamburger test.
In thistest, youeat a V4-pound hamburger andthendrinka liquid that contains the heavy element barium.
Every halfhourorso, anX-ray photo istaken ofyour stomach.
Since the barium shows up in these photos, the radiologist
*If, during anR-R study, your heart rate varies only 28 percent between inhaling and exhaling, then you will likely have mild gastroparesis. If the variation is about20percent, gastroparesis will probably bewhatI call moderate, and if less than 15 percent, I would call it severe.
362 Treatment
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 any where near 100 percent sensitive, because of the unpredictable nature oftheparetic stomach.
One day it may empty normally, another day it may beabitslow, and onyet another day its emptying may beseverely delayed.
Because of this unpredictability factor, the study may have to berepeated a number oftimes before a diagnosis can bemade.
Thepos sibility exists that you could have several normal studies but still have abnormal stomach-emptying.
I therefore advise my patients against using either ofthese two tests.
The R-R study ismy 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 manyyears agowhenI 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 yourbloodsugarlevels and try ing to keep them in the normal range, it's really not difficult to spot gastroparesis that'ssevere enough to affect bloodsugars.
Forpractical purposes, thisisjustthedegree ofgastroparesis thatshould 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 goin such a fashion that bloodsugarpro files are rarely similar on 2 or 3 successive days.
The first two patterns together arehighly indicative of gastroparesis, while the third byitself is usually adequate for diagnosis.
• Lowblood sugar occurring 1-3 hours after meals. • Elevated bloodsugar occurring 5 or morehours aftermeals with no other apparent explanation. • Significantly higher fasting blood sugars in the morning than at bedtime, especially if supperwas finished at least 5 hours before retiring.
If bedtime long-acting insulin or ISA is gradually in creased 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
DelayedStomach-Emptying. Gastroparesis 363
other days it may be normal or even too low. We're thus giving extra bedtime medicationsto accommodate overnight stomach- emptying, but sometimes the stomachdoesn'tempty 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.
Skipsupper and its premealinsulinor ISA one night.
When you go to bed, be sure to take your basal (bedtime) insulin or ISA, measure your blood sugar,and then measureyour 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 severaldayslater,and again a third time, af ter another few days.If each experiment results in the same effect,de layed stomach-emptying is virtually certain on one or more of the nights when you had eaten.When you had previouslybeen eating sup pers, at least some of the following mornings had shown an overnight rise in blood sugars.
Sincesuch rises occurred on nights when you had eaten supper, but noton the nights when you did noteat, 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 slighdy impaired.
These people had delayed stomach-emptying but well-functioning vagus nerves.
The conflictingdata obligedme to order upper gastrointestinal endo scopicstudies for these people.
Endoscopyuses a thin, flexible, lighted fiber-optic cableto look directlyinto 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
364 Treatment
treatment for diabetes.
Only with hiatal hernias were we unable to at least partially alleviate the digestive problem.
In such cases, however, surgicalcorrection 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 gas- tropathy 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.