'Starvation in the Midst of Plenty' 

Diabetics have all the glucose they could ever use, but it can't get into the cells to go to work.

By Capt. Robert Sancetta (Gemini), M.D.
Air Line Pilot, February 2005, p.21

This article is adapted with permission from the Gemini MEC newsletter Jet-Tribune, December 2004.

In my medical practice, diabetes mellitus is second only to heart disease as the most common diagnosis that requires a formal "special issuance" for a pilot to keep flying. Diabetes is 1 of the 15 formally "grounding" medical problems as defined in the federal aviation regulations (although, as many of you know, an almost unlimited number of problems requires some documentation to be reported to the FAA Aeromedical Certification Division in Kansas City for a pilot to remain on flight status). 

Diabetes, defined as simply as possible, is abnormally high blood glucose (sugar). This high glucose level in the blood is caused by a number of factors. The high blood glucose is a result of something that prevented the glucose from getting into the various cells of the body, where it's needed to provide the nutrient that the cells require. This is why it's called "starvation in the midst of plenty." You have all the glucose you could ever use, but it can't get into the cells to go to work. The cells don't like that very much, and the body goes into a process called "ketosis" to keep the body's basal metabolism rate going, often sacrificing muscle tissue-breaking it down into required nutrient components. (I know, all you Atkin's junkies are jealous that some folks are already in the coveted ketotic state that you seek, but it's not nearly that much fun, as I'll describe later.)

How the body processes glucose 

The cells and tissues of the body all require glucose for energy demands. Although other nutrients are important, the brain uses glucose exclusively as its sole energy source. The pancreas (an organ near the stomach and liver in the abdomen) is involved in several aspects of digestion. It has groups of "beta cells" that produce insulin, which facilitates the entry of glucose into the cells as needed. The pancreas, therefore, initially determines the balance of blood glucose and the entry of glucose into the cells. That's not the whole story, however, as you'll see.

Different kinds of diabetes 

The basic subtypes of diabetes include Type I (insulin-dependent or juvenile diabetes) and Type II (noninsulin-dependent or adult-onset diabetes). 

Type I diabetes is the worst of the two. It is typically identified in early childhood, thereby giving the disease many years to cause its varied problems. In juvenile diabetes, the beta cells of the pancreas basically stop producing insulin. There are many theories as to why this happens, and this may be another of the many annoying things that an autoimmune reaction might cause. Patients with Type I diabetes spend their entire lives taking insulin. Historically, this has been by self-injection two to four times per day, a process that dominates virtually the entire day for the patient. Fortunately, the newer version of insulin pumps has streamlined the labor-intensive process of taking finger-stick glucose readings and mixing up individual shots of insulin several times daily. It remains labor-intensive to a degree, but this technology has greatly liberated the Type I diabetic from some of the ongoing drudgery of the disease. 

In Type II diabetes, the pancreas typically continues to produce insulin, albeit usually at a lower rate than it had previously. In spite of some residual insulin production, the blood glucose has trouble getting into the cells, because for some reason the cells have become resistant to absorbing the glucose. In mild cases, this might be treatable with diet and exercise. In moderate cases, some oral medications work pretty well. In severe cases, even Type II diabetics might wind up taking insulin. Type II diabetes often appears later in life, giving the disease less time to do its dirty work.

Complications 

Eventually, the high blood glucose wreaks havoc on the walls of the blood vessels themselves. This greatly increases the risks for both cardiovascular and cerebrovascular disease. In other words, diabetics have a much higher risk of heart attack and/or stroke than non-diabetics. As a matter of fact, by the time diabetes is diagnosed, close to 50 percent of patients already have some early manifestations of heart disease. Small- and medium-sized blood vessels anywhere in the body are also at risk. Other organs commonly affected are the eyes and kidneys. Diabetes is the most common cause of blindness in the United States. Kidney failure is a possibility. Neuropathy (injury to nerves that can cause pain and numbness) and foot ulcers, which are difficult to treat, are prevalent if the disease isn't aggressively controlled. The complications of diabetes are significant and cause a tremendous amount of inconvenience, expense, and disability. 

In addition to these long-term complications, diabetes can be pretty miserable to deal with in the short run. In exacerbations, the excessively high blood sugar can cause the brain to malfunction, leading to symptoms that range from confusion to coma and even death. The amount of acid in the bloodstream can elevate, causing the kidneys and lungs to go into overdrive to try to correct things. Everything about diabetes is stressful to a multitude of metabolic processes.

Diabetes prevention 

At the present, not too much can be done to prevent juvenile-onset diabetes. A tremendous amount of research is going on at institutions such as the Barbara Davis Center for Diabetes, located in Denver. A cure for this disease may not quite have the news media appeal as a cure for cancer or AIDS, but it is every bit as significant and needed. 

To prevent adult-onset diabetes, controlling risk factors to the best of our abilities is essential. Risks include, of course, genetics. Choose your parents wisely. A family history of diabetes must be taken very seriously. In someone with that family history, a sedentary lifestyle and obesity greatly increase the likelihood of developing the disease. Trust me, I don't bug my obese pilot patients about their weight just for the fun of it. From hypertension to heart disease to diabetes, obesity increases all kinds of risks. 

Exercise has an important role in both the prevention and management of diabetes, among other illnesses. Exercise improves the ability of body tissues to process glucose. Additionally, it tends to help people keep their weight in check, reducing another risk factor. As long as I'm on a roll here, allow me to add that exercise also improves blood pressure and outlook on life, helps a person control addictions such as smoking, and reduces the risk for heart disease and stroke. Take-home message: aerobic exercise is pretty good for you. Augment this with some moderate resistance training, and you'll be in great shape for your senior years.

Pilots who have diabetes 

If a pilot requires insulin, the only class of medical certificate available at this time is a third-class. This has been permitted only since 1996, and it has allowed well-controlled insulin-dependent diabetics access to the cockpit, finally. This permits a pilot to fly privately, and even to flight instruct. Canada has begun certifying some pilots on insulin to fly commercially--so far with success. I am hopeful that one day the FAA might permit this, too, if it can be done safely (I am beginning to believe that this is indeed possible, and I support a protocol to research this further). 

If a pilot has Type II diabetes and does not require insulin, then first- and second-class FAA medical certification is available. I have in my practice numerous pilots with Type II diabetes who are flying as captain in FAR Part 121 operations. 

As diabetes is a formally disqualifying diagnosis, a pilot with diabetes requires a "special issuance" to obtain a medical certificate. This is, fortunately, about the simplest of the formal special issuances to achieve. 

Studies have shown that the better and more carefully a person controls diabetes, the better off the person is in the long run. Complications can be delayed and/or prevented if that person is dedicated to risk modification and control of the disease. Take it seriously, in other words.

Diagnosing diabetes 

In a child, the early symptoms might include weight loss, difficulty in school with memory and mental status problems, excessive thirst, and frequent and excessive urination. Measurements might show blood glucose readings in excess of about 140 mg per deciliter. Sometimes a glucose tolerance test is prescribed as confirmation. In this test, the person drinks a glass of really concentrated sugar solution, and then blood glucose measurements are taken for a few hours to see how well the body metabolizes the sugar load (most people find this stuff pretty awful, but I am convinced that if my 13-year-old stepdaughter discovered it she'd become instantly addicted and would probably start selling it to her classmates in kind of an obscene 7th grade black market). 

In an adult, symptoms also include excessive thirst and frequent and excessive urination. Of course, I always worry about the "obese sloth" factor, and it is not uncommon for me to see this scenario: a pilot who I've bugged about losing weight for years, and who typically has come in 3-5 pounds heavier each and every exam, suddenly shows up having lost 8-12 pounds since the last time I saw him. If the pilot says he doesn't know why he lost weight, red flags go up immediately. I will on the sly, without worrying him if I can avoid it, try to research if other symptoms might have been in play. Although the FAA exam does not require blood work, the proof is often in the required urinalysis. If this pilot has now "spilled" some glucose into his urine, almost certainly he has adult-onset diabetes. In this case, I send the pilot for screening blood work, which usually confirms the diagnosis.

Treatment and FAA recertification 

Once a pilot has been diagnosed, he is grounded until it can be shown that he is stable and until the FAA reviews the case and issues the special-issuance authorization (note: I don't mean to exclude our female colleagues by resorting to the masculine reference, but when we're discussing heart disease and diabetes in pilots, almost all are male, although women get plenty of medical problems, too, unfortunately). If the pilot doesn't murder me after I inform him that he is grounded, the good news is that if the disease is mild, the pilot may be back in the cockpit in as little as 60 days. For most pilots, once they get through the initial denial and anger stages, recertification comes pretty quickly. Basically, this is a mandatory 2-month vacation while they learn how to control the illness. Enjoy the time off, I tell them, and use the time to learn everything they can about the disease. Plus, this is a good time to start walking when playing golf (other than if a person is disabled, I think golf carts should be outlawed), getting on the ball with other forms of exercise, adapting to a "diabetic diet," and starting to lose weight (some lean folks just get "lucky" and develop the disease purely on a genetic basis, but the vast majority of adults who develop diabetes are the typical overweight and sedentary types). 

Once diagnosed, the pilot will receive education on diet, exercise, medications, and all aspects of daily care of the disease. This is typically done by an endocrinologist (a specialist in the treatment of disorders of glands, hormones, etc.), but any internist or family physician who is motivated can treat this disease effectively. The pilot will learn how to take blood glucose readings, and will, unfortunately and laboriously, do so several times a day until he has a good understanding about the control of his disease. Typically, oral medications are prescribed. These have several mechanisms of action, and they lower the blood glucose to levels that hopefully prevent some of the blood vessel and organ damage described earlier. It's up to the pancreas to continue to make at least some insulin and for the pilot to exercise and hopefully lose some weight, thereby helping facilitate the body tissues to process the glucose. Many oral hypoglycemic medications are available for a pilot to fly on, once he is approved for the special issuance. 

In addition to home glucose readings, a pilot is required to obtain formal blood work from the lab occasionally, typically including at minimum a fasting glucose and hemoglobin A1C (HbA1C, or glyco-sylated hemoglobin). This is a great test. It measures how much glucose has affected the red blood cells. Because a red blood cell typically lives about 90-120 days, this test gives us a 3-month picture of the overall control of the disease. Some routine additional blood work should also be included in the initial application to the FAA. 

On the pilot's initial certification after the diagnosis, some added criteria have to be met. Since diabetes can cause damage to the eyes (diabetic retinopathy), a full eye exam is required, and the eye specialist will have to confirm that the pilot's eyes are without significant disease (this is reported most commonly on FAA Form 8500-7, which I supply to my pilots to bring to their eye doctors). If any concern for heart disease exists, the pilot may be required to undergo a formal cardiac evaluation, which will most likely include a treadmill test and anything else the cardiologist feels is required. 

Follow-up documentation is very simple. For a first- or second-class medical, this is required only once every 6-12 months. Typically all that is required is a current HbA1C and short update statement from the treating physician that the disease remains under good control (including medications used and that there are no side effects of concern), that other organ systems (eyes, kidney, neurologic, etc.) are not compromised, and that the pilot has had no "hypoglycemic" reactions. This means that the pilot has had no instances in which overmedication might have caused the blood sugar to actually drop too low, which might cause a blackout (this is very unlikely in Type II diabetics, but it is something that all insulin-dependent diabetics have to be very careful with). 

The FAA has finally started allowing aeromedical examiners who are interested in special-issuance certification to actually perform the follow-up recertifications for diabetics on the spot (as long as the data look good), including first- and second-class medical certificates. This is an excellent improvement to the recertification process. Not all AMEs are interested in taking on this additional responsibility, so the pilot will have to seek out an AME who is motivated toward helping pilots who require a special-issuance authorization.

Conclusion 

Diabetes is a disease of glucose metabolism that can cause widespread tissue and organ damage. The goal is to control the disease as best as possible once the diagnosis is made. Preventing complications through careful control of blood glucose decreases the risks for heart disease, cerebrovascular disease, blindness, kidney failure, etc. Oh, did I forget to mention that impotence is a complication of poorly controlled diabetes? Got your attention now, didn't I? 

While diabetes is a formally disqualifying diagnosis, FAA medical certification can be regained via the special-issuance process. If the pilot requires insulin, then at best he can get a third-class medical certificate. If the pilot can control his diabetes with diet and exercise, or with oral medications, then any class of medical certificate may be obtainable. Typically, it takes only about 60 days to demonstrate control and to reapply for FAA medical recertification. 

Controlling diabetes as best as possible can delay the onset of complications. That is most important, as it helps ensure a long and functional lifestyle. Additionally, good control facilitates expedited FAA medical recertification.