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What is diabetes, and how does it affect your medical?

What is diabetes, and how does it affect your medical?

Life is sweet, especially when one lives in Alaska and has an opportunity to fly wonderful airplanes to incredible places. However, when sweetness affects your body, not only is your health in jeopardy, but so is your Medical Certificate. As an Aviation Medical Examiner, I have encountered many diabetic pilots in my 20 plus years of performing flight physicals, and it is always disconcerting (mostly to the pilot, of course) when this diagnosis is made during a flight physical examination. As with other medical problems, there are 2 sides to this coin…that of one’s health, and that of one’s Medical Certificate. I would like to take this opportunity to describe briefly what diabetes is, why it is becoming an increasingly frequent problem, and what can be done about it….for one’s health, and one’s Medical.

There are basically 2 types of diabetes, insulin-dependent (Type I) and non-insulin dependent (Type II.) In order to understand the difference, bear with me a short review of the biology involved. This will help you understand how these diseases operate, how treatment works, and then how the FAA deals with it.

It is important to understand a couple basic premises. First, every cell in your body needs fuel, and that fuel is glucose and glucose only. Glucose is like avgas for your plane….without it, no work can be performed. It is the basic building block of all forms of carbohydrates, which are eventually broken down into glucose for each of your body’s cells to use. However, the cell cannot recognize glucose floating in the bloodstream by itself. It must be informed that it is available for use, and this signal is insulin. Each cell of our bodies has insulin receptors attached to it, and when insulin comes into contact with these receptors it activates them and signals to the cell that glucose is available. This action opens up the cell to glucose and brings it in, so that it can now be used by the cell for fuel. Without either insulin or these receptors, cells could literally be swimming in a sea of glucose and not know it!

Secondly, there are potential problems with insulin production, and there are potential problems with insulin receptors. This is where Type I and Type II diabetes differ. In insulin-dependent diabetics, the body (for whatever reason) has quit making sufficient amounts of insulin. Such a person can eat carbohydrates, break them down into glucose units, and yet the cells can starve because there isn’t enough insulin to tell them that glucose is right outside waiting to come in. Insulin is produced by the pancreas, and under normal circumstances the amount of insulin secreted exactly matches the amount of glucose rising in the blood stream. This occurs rapidly and from moment to moment.

Type I diabetics need to receive insulin in the form of injections (science has not yet perfected a form of insulin that one can swallow) and of course it is important to match the amount of insulin as closely as possible to the amount of carbohydrates ingested. Because it is difficult, if not impossible, to duplicate this exact and rapid matching of insulin to glucose levels in the blood with injections, insulin-dependent diabetics can have high and low swings of blood sugar. If too high too often, critical cells in blood vessels are injured and the long-lasting complications of diabetes will ensue: infections, loss of circulation, kidney disease, blindness, and early death. If too low, the brain can’t get the food it needs to remain conscious, and disorientation or fainting can result. If not quickly resuscitated with supplemental glucose, the hypoglycemia brain can have permanent damage, and the person can die.

Non-insulin dependant diabetes, on the other hand, results from receptor failure. If the cell’s insulin receptors do not work properly, more and more insulin is produced by the pancreas in response to rising blood sugars. Although these people can have very high levels of insulin in their bodies, their cells cannot recognize it, and therefore don’t respond by taking the glucose in. These people need to be treated with methods that increase the receptors’ sensitivity to insulin, so that they can “wake up” to the fact that there is sugar out there to be taken in. Here is where it gets interesting, just bear with me!

There are people who have a genetic predisposition to insulin receptor dysfunction or, in more common terms, insulin resistance. They need to be treated with careful attention to proper diet (limiting caloric intake) and perhaps medications that increase their receptors’ sensitivity to insulin. Once these receptors “wake up” they can again recognize the naturally secreted insulin and take in the glucose. Please understand that this is not a cure, but a treatment that will probably be lifelong.

On the other hand there are people who develop insulin receptor resistance because of obesity and sedentary lifestyle. It is a known fact that being overweight somehow interferes with the sensitivity of the insulin receptors, and that the fatter one gets, the more resistant these receptors become. These people can frequently get rid of their diabetes by losing weight and exercising, and getting down to a normal body mass index (between 18-25 % body fat.) So, knowing that obesity can directly cause diabetes, it is not surprising that this disease has become an epidemic in this country, as 60 % of Americans are now overweight. The treatment is simple….eat less and exercise more!

Note that nowhere in this article have I stated that sugar causes diabetes. It definitely does not. What causes diabetes is a complex interplay between one’s genetics and one’s lifestyle. The more genetic predisposition one has for developing diabetes the easier it is for an individual to develop it if he or she is overweight. Eventually it seems that most people who are obese develop problems with the internal signals for proper glucose metabolism. It should be noted that being obese shorten one’s lifespan in other ways such as increasing one’s risk of high blood pressure, cancer, physical injuries, and psychological problems such as depression.

There seem to be very few people who develop diabetes purely from genetic reasons or purely from bad lifestyle choices, as in most cases there is an interplay between both causes. Whatever mechanisms are involved in producing an individual’s diabetes, one can still improve one’s life and lifespan by getting regular exercise and keeping weight to normal, as this reduces the risk of all those other nasty problems mentioned in the previous paragraph.

So, how does an airman first get identified as having a problem with sugar metabolism on his or her flight physical? By having glucose in their urine on examination. Granted, even “normal” people can, under extreme circumstances, have glucose in their urine if they had ingested a HUGE amount of sugar just prior to their examination. But the emphasis is on HUGE. Under normal circumstances, there should not be any sugar in the urine, because the kidneys are able to handle normal sugar loads and prevent it from spilling over into the urine from the bloodstream. If an individual exceeds his or her kidney’s ability to handle this load by ingesting a very large amount of glucose, some glucose might end up in the urine. The question of whether or not such a person has diabetes can then be answered by a couple simple blood tests, such as measuring their blood sugar and their “glycosylated” hemoglobin. The blood sugar can determine the amount of glucose in the blood at the time it was drawn (but not where it has been or where it goes in relationship to a meal) and the glycosylated hemoglobin (also known as a hemoglobin A1C) can determine how high it has been in the past 2 months or so. The FAA of course has its limits of what it will accept, but for the purpose of this article I won’t go into that kind of detail.

OK, so what about your Medical Certificate? Basically, diabetes is one of the 15 disqualifying medical conditions that have been identified by the FAA. That doesn’t mean that one cannot fly! The FAA has several categories of Special Issuance for diabetics who are well-controlled, and here are the rules:

1.) For insulin dependent diabetics, only Class III Special Issuance is allowed. Because it is so difficult even with today’s technology for these diabetics to perfectly regulate their blood sugars, especially to avoid hypoglycemia, the FAA only allows certification for Class III. However, not every insulin dependant diabetic will get a favorable review by the FAA, only what I call the “cream of the crop” diabetics. These are people who have demonstrated excellent control of their diabetes, are meticulous in their insulin and dietary management, have no episodes of hypoglycemia, and have no other significant medical problems that would interfere with their disease management. The FAA also has rules about checking blood sugars prior and during flight, and prior to landing. It gets complicated, but seems to work OK. Currently there are about 300 or so such insulin-dependent diabetics flying in the USA…and nowhere else in the world are they granted this privilege!

2.) For non-insulin dependent diabetics who are able to control their blood sugar by diet and exercise without medications, they are considered eligible for all classes of medical certificates, provided they have no evidence of associated disqualifying heart, circulatory, kidney, neurological, or eye diseases or complications. They do not need any additional specific testing unless it is indicated by their history or examination. No Special Issuance is required as long as they remain purely diet and exercise controlled.

3.) Airman with a diagnosis of diabetes controlled by use of an oral medication may be considered for Special Issuance for all three classes of Medical Certification. Per the FAA protocol, “following initiation of such oral medication, a minimum 60-day period must elapse prior to certification to assure stabilization, adequate control, and the absence of side effects or complications from the medication.” It is important to note that the FAA has to make the initial certification decision, not the AME. Recertification decisions will be made on the basis of reports from the treating physician, and these reports basically have to have the same information as the initial report. Usually for airman under good control, the FAA will issue a 6 -year Special Issuance Authorization, with each Medical Certificate being valid for only one year at a time. As long as the Special Issuance Authorization is in effect and the annual reports from the treating physician are favorable, the AME may issue a time-limited certificate of one year (for all Classes), while future medicals must be based on continuation of good control. This information is forwarded to the FAA and reviewed for correct handling by the AME. Recertification by the FAA occurs when the Special Issuance Authorization has expired, or the airman’s diabetes management has changed.

To learn more about Special Issuance processes, even for other disqualifying conditions other than diabetes, there are a variety of good web sites available to you:

FAA: www.FAA.gov and go to Aerospace Medicine under Quickfind, and poke around. It’s a little cumbersome, but you can find the information.

AOPA: www.aopa.org, and click on “medical”

ALPA Aeromedical (this is the web site for the doctors for the Airline Pilot Association, who call themselves the Virtual Flight Surgeons here…and I believe this is the best web site for all aeromedical problems) at www.aviationmedicine.com

Or you are welcome to contact me directly if you prefer. I can be reached at:

Aviation Medicine Services of Alaska
5011 Spenard Rd. #102
Anchorage, AK 9957
(907) 245-4359
email: This email address is being protected from spambots. You need JavaScript enabled to view it.
web site: www.AirSpaceDoc.com

So, it is obvious that most cases of diabetes are eligible to fly under Special Issuance, but also clear that it requires commitment by the airman to manage this very serious health problem. Remember, the priority is to your health, and your Medical Certificate will follow you wherever you go!