Questions and Answers
Why Have I Lost Depth Perception in My Vision?
Q: I have had type 2 diabetes for almost 20 years. I have been injecting insulin for approximately seven years, and, while my control isn't perfect, it is much better than in earlier years. Over the past few years, I have had a few laser surgeries on both eyes with good results. But I do have a question that no eye-care professional has an explanation for. My depth perception has decreased noticeably over the last couple of years, to the point where driving is becoming a challenge. The retinal specialist who did the surgeries on my eyes has no explanation; neither does the ophthalmologist I see for routine eye care. Last year, I traveled to the Johns Hopkins Hospital's Wilmer Eye Institute for an evaluation, and the ophthalmologist there could not explain the loss in depth perception. Except for the loss of depth perception, my vision is good! Can you offer an explanation for this condition? You are my last hope.
A: Without examining your eyes, I can only venture a couple of guesses at what's going on to explain your poor depth perception after the laser surgeries. First, be aware that in order for you to have good depth perception, both eyes have to be working well together. What happens sometimes after laser surgery is that you lose a little bit of peripheral (side) vision as a result of the "burn" spots that the laser creates in the retina. This sometimes makes it a little harder for the eyes to line up and causes this problem. In addition, the "burn" spots also decrease the amount of light taken in by your retina, which is why the problem is more pronounced at night. If this poor depth perception gets to be a major problem (which it sounds like it is becoming), go to a doctor who handles a lot of binocular problems to see whether he or she can rule out a microstrabismus and perhaps do a visual field test to map out your peripheral vision.
Deepak Gupta, OD, FAAO
When Is an After-Meal Blood-Glucose Reading Most Effective?
Q: I had learned that standard after-meal blood-glucose measurement was supposed to be taken two hours after a meal. However, with more attention focusing on damage from after-meal excursions, it appears that patients and researchers are finding that the post-meal peak more typically occurs about one hour after a meal.
I realize that there are many factors involved, including the glycemic index of the meal and possibly autonomic neuropathy. Is it more accurate in general to recommend to patients to check their blood glucose one hour instead of two hours after a meal to find their most accurate after-meal peak?
Karen Lavine, RN, CDE
Albuquerque, New Mexico
A: Your question relates to some of the many factors that influence the after-meal glucose rise. Much more attention is being given to after-meal glucose levels as representing effects on cardiovascular risk in addition to overall diabetes control. The 2002 Clinical Practice Guidelines of the American Diabetes Association do not include a goal for after-meal blood glucose for nonpregnant adults. The August 2001 Summary of Recommendations from the American College of Endocrinology Diabetes Mellitus Consensus Conference states that the blood-glucose target for nonpregnant adults is less than 140 mg/dl two hours after a meal. This target is for plasma blood glucose (lab values or meters calibrated to plasma-equivalent readings). There is no mention of a one-hour after-meal target. Perhaps people with diabetes should occasionally check their blood glucose both one and two hours after certain meals to learn their individual patterns of response. This would be especially helpful to those learning to match rapid-acting insulin doses to carbohydrate counts. The latest guidelines for managing diabetes during pregnancy now focus on one-hour after-meal blood-glucose levels for monitoring, in addition to fasting levels. The one-hour after-meal levels during pregnancy correlate best with peak blood-glucose excursions after breakfast, but not always as closely with peak blood-glucose levels after dinner.
Cindy Onufer, RN, MA, CDE
Question About Treatment of Neuropathy of Feet and Legs
Q: A response by Aaron Vinik, MD, to a reader's question in the November 2001 "Ask the Expert" section ("What Medications Can I Take for Neuropathy of the Feet and Legs?" p. 52) raised a question in my mind. Dr. Vinik states, "If the pain is between the first and second toe and there is tenderness in that space, then it is due to Morton's neuroma, which is best relieved by excision."
I am not a surgeon, but it is my understanding that pain between the metatarsals is often caused by a neuroma, which is the result of pressure on an interdigital nerve or nerves. Neuromas are common in dancers, runners, basketball players and other active people. Relief is often made possible by reducing this pressure. A person might be able to achieve relief nonsurgically by wearing shoes with ample space in the forefoot, using a metatarsal pad behind the heads of the affected metatarsals, or taping felt pads between the affected toes.
Correct me if I am wrong, but perhaps this information should be known to people with diabetes who might otherwise assume that all foot pain is neuropathy and that the only means of treatment is surgery.
Kris Berg, EdD
Diabetes Health Exercise Adviser
A: Kris Berg is right when he suggests that dancers and exercisers who repeatedly land on their feet get neuromas from repeated minor trauma to the interdigital nerves. He is also right to suggest that the best treatment at an early stage is alleviating the repeated trauma by metatarsal bars, shoes that are wide in the forefront and interdigital pads.
I find this extremely interesting because I exercise religiously and began to experience considerable, almost incapacitating, pain in the dorsum of the foot. I consulted rheumatologists, orthopedic surgeons and podiatrists, who made all sorts of suggestions. I finally bought a larger pair of shoes from a person who is an orthotist as well as a shoe retailer. As one grows older and exercises, one's feet grow, and all I needed were new shoes 1 1/2 sizes bigger!
As for Morton's neuromas, if the pain persists in the interspace and there is a clear neuroma on MRI, excision becomes the only choice. No doubt prevention is better than cure, and, as Kris knows, people with diabetes often have neuropathy that does not allow them to perceive the pain which would alert them to the fact that they are generating a neuroma.
Many of the articles I have written on pain in people with diabetes indicate that it may result from a variety of causes such as arthritis, gout, fasciitis or claudication, to name a few, and each person needs to be treated according to the cause of pain. Kris clearly misunderstood me when he says that I suggest that the treatment of "neuropathy" is surgical.
Aaron Vinik, MD
Eastern Virginia Medical School
Treatment for Frozen Shoulder
Q: Regarding Tom Gorecki's question about frozen shoulder in the "Ask the Expert" section in the November 2001 issue (p. 45), I have been taking insulin for 50 years and was not always in good control. I am now on the pump and my control is quite good. About 20 years ago, I was in great pain with frozen shoulders on both sides. I was not able to reach either arm over my head. My orthopedic surgeon treated them both by manipulating them while I was anesthetized (forcing them to move past what I was able to manage while awake). This treatment was followed by several weeks of physical therapy and exercises on my own.
The first time my shoulders were treated, the pain recurred in both of them in about a year, and the treatment was repeated. Since that time, I have had full motion in both shoulders with no further pain.
Since this was not mentioned in Dr. Bernstein's reply, I am wondering if this treatment is no longer used. I was told there was the possibility that my shoulder could be broken if the manipulation was not carefully administered. Maybe that is the reason it is no longer done, but I consider myself very lucky to have experienced such relief from this problem.
A: I have seen many people with diabetes with frozen shoulders who had been treated by orthopedic surgeons. All of these surgeons injected cortisone into the affected sites—with only temporary effectiveness. The skill of your orthopedist was so remarkable that I suspect he or she was trained in the United Kingdom, where—prior to the institution of socialized medicine—true hands-on care was practiced. You were most fortunate to have been successfully treated in this fashion. Because of the potential for injury, I would be reluctant to recommend that a physician trained in the United States attempt such treatment. Please send me a note in care of Diabetes Health to let me know whether I guessed correctly about your surgeon's training.
Richard K. Bernstein, MD, FACE, FACN, CWS
Mamaroneck, New York
How Can I Treat a Burning Sensation in Both Feet?
Q: I am a 71-year-old male living at South Lake Tahoe, and I have had type 2 diabetes for a little more than five years. I have very severe pain and a burning sensation in both feet, especially in the ball of my foot; it is also very intense in all my toes. My doctor has suggested that I ride my stationary bike for 15 minutes three times a day. I have been doing it for some time, but with no results so far. Can you give me any advice to alleviate the pain, either medication or something else? I would be most grateful.
South Lake Tahoe,
A: You are not alone. It sounds like you may have diabetic peripheral neuropathy (DPN). Diabetes can affect the nerves, creating pain in some people and numbness in others. You seem to have the painful type.
There are many treatments for DPN. Most important of all, good glucose control is essential. As for specific treatments, if one doesn't work, we try the next. Try capsaicin cream 0.075 percent, which is made from hot peppers, first. You can get it over the counter. Rub it on three to four times a day using a small plastic baggie or glove to cover your hand during the application. Be very careful not to get any of the capsaicin in your eyes or mouth, as it will burn. Frequently, the pain goes away in three to six weeks. Alpha lipoic acid, also available over the counter, helps some people. And the compression of support stockings makes some folks more comfortable.
If these approaches don't work, your podiatrist or diabetes doctor may want to give you a prescription medication. I usually start with amitriptyline (Elavil) or gabapentin (Neurontin). I start with small doses and work up to larger amounts until the pain is controlled.
Neil Scheffler, DPM
Do Protein and Fat Add Glucose to the Blood?
Q: I have a question regarding the article "Are There Good and Bad Carbohydrates?" in the March 2002 issue (p. 64) by Marion J. Franz, MS, RD, CDE. In the third paragraph, it says that protein and fat do not add glucose to the blood.
Other medical books I have say different things. They say that both protein and fat do add a minor amount of glucose to blood levels. Carbohydrates are the primary source, but not the only source. Which is correct?
Alex van Luik
A: Indirectly, protein may contribute some glucose to the blood, but when and how much are uncertain. The nonessential amino acids are changed into glucose in the liver, but this glucose does not enter the blood. People with diabetes were often told that about 50 percent of protein eaten would change into glucose and enter the blood three to four hours later. Recent research has shown this is not the case. Although some protein does change into glucose in the liver, the fate of this glucose is not known for certain at this time. It is speculated that this glucose is stored in the liver as glycogen, as is some carbohydrate; when needed, glycogen releases glucose into the blood. At this point, we would not know whether the glucose came originally from protein or from carbohydrate. However, to be metabolized, protein does require as much insulin as does carbohydrate. In fact, in some people with type 2 diabetes, protein may require more insulin than carbohydrate. So if the amount of insulin available is inadequate, it may be possible that blood-glucose levels would increase. This last possibility, unfortunately, has not been well researched.
Fat does not contribute glucose to the blood, either. The fatty acids from food fat are primarily stored in fat cells to be used when needed for energy. However, some research has reported that large amounts of food fat can cause insulin resistance. This also might have the effect of raising blood-glucose levels. Again, this is not very well studied.
As you can tell, factors that affect blood-glucose levels are not as simple as the information often presented to people with diabetes. The main point to remember, from the standpoint of what is important clinically, is that the total amount of available carbohydrate eaten will be the primary determinant of what happens to blood-glucose levels after eating. This does not mean people with diabetes should avoid carbohydrates. Foods that contain carbohydrates, such as grains, fruits, vegetables and milk, are important for a healthful diet. But it does mean your body must have enough insulin to metabolize the carbohydrates, just as it must have enough insulin to metabolize protein and fat.
Marion J. Franz, MS, RD, CDE
Nutrition Concepts by Franz, Inc.