Healthy Pilot #9: Diabetes And Your License to Fly
The diabetes epidemic in this country, brought on by environmental factors and lifestyle choices, can follow you right into the cockpit.
The whole-body impact of type 1 or type 2 diabetes can affect eyesight, heart function and kidney output. It can lead to fatty liver disease, skin infections, osteoporosis and even dementia. No other disease--except perhaps an autoimmune disorder--carries this kind of whole-body risk. Clearly, losing any of these capacities risks your pilot privileges, let alone several at once. Diabetes is items 18K on the FAA's Basic Med Checklist.
For this article, AVweb consulted sister website University Health News to get a broad overview of diabetes symptoms, diagnosis and treatment. UHN offers a wealth of content on the subject, but these two articles, How to Avoid Diabetes, and What You Should and Shouldn’t Eat If You Have Diabetes, are particularly useful.
We also consulted the FAA circular on the subject of diabetes mellitus, and circled back to AOPA’s pilot resource area on the topic. Bottom line: A diagnosis of diabetes mellitus is a disqualifying condition, but pilots can retain their privileges with a special issuance. Jumping through those hoops will be a challenge but well worth it for qualifying pilots who want to continue to fly.
Clearly, checking "yes" on item 18K should prompt a discussion with your examining physician and lead to an opportunity to solicit comments or explanations. If diabetes management has become a part of your life--and it's well controlled with medications--you and your doctor may decide it's OK to fly. But if you want to stay legal, you need to fess up. If you sign your Basic Med documents and you know you may have a medically disqualifying condition, you've broken the law.
What is diabetes exactly?
Diabetes, also known as diabetes mellitus, is the name of a group of diseases in which the body is unable to properly utilize blood sugar (glucose) for energy. There are three primary forms of diabetes—type 1, type 2, and gestational diabetes— and, in each case, the body is unable to effectively move the glucose that results from the metabolism of the sugar and starches into the cells of our muscles, brain and other vital tissues. The net result is that the body’s cells are deprived of their energy source and the blood sugar or glucose builds up in the blood.
We'll confine this discussion to type 2 diabetes, as that form of the disease impacts 90 to 95 percent of diabetes cases and typically has a later onset. The cells of the body, particularly those of the fat, liver and muscle tissue, have some degree of resistance to the effects of insulin in type 2 diabetes. Insulin is the hormone that moves blood glucose to the cells where it can be utilized. As a result, blood glucose increases, and the pancreas tries to keep up with production of more insulin, soon becoming dysfunctional.
The insulin resistance that characterizes type 2 diabetes is thought, like type 1 diabetes, to be caused by a combination of genetic and environmental issues. Here is a list of risk factors:
- Family History: Having a parent or sibling with type 2 diabetes increases your risk of developing the disease.
- Obesity: Obesity or increased weight is one of the best risk factors for development of type 2 diabetes. Having higher quantities of fatty tissue increases the resistance of the body’s cells to insulin.
- Sedentary lifestyle: Exercise helps the body use glucose and increases cells’ sensitivity to insulin. Additionally, exercise helps control weight. Lack of exercise or physical activity therefore increases your risk of weight gain, higher glucose levels, and insulin resistance.
- Ethnic background: Type 2 diabetes is more common in African-Americans, Hispanics, Native Americans, Alaskan natives, Asian Americans and Pacific Islanders. The reasons for this increased risk are not yet understood.
- Age: The risk of developing type 2 diabetes increases as you age, particularly after the age of 45. This may be due to the tendency to have a less active lifestyle as you age and the weight gain that subsequently occurs.
- Diet: Research has suggested that a diet high in saturated fats might be a risk factor for type 2 diabetes.
- Lipid levels: Having low high density lipoprotein cholesterol (HDL) levels (usually below 35 mg/dl) and/or high triglyceride levels (usually above 250 mg/dl) has been associated with an increased risk of type 2 diabetes.
Symptoms and Signs of Diabetes
One of the first signs of diabetes may be numbness or tingling in hands or feet, part of the neuropathy that people with diabetes often suffer. Diabetes symptoms also include frequent urination, increased thirst, increased hunger, fatigue and blurry vision. Also be on the lookout for slow-healing cuts or bruises, increased infections of the skin or gums, or dry skin.
Be aware that some don't experience symptoms initially, according to the American Diabetes Association. Therefore having your blood glucose level checked every three years if you're older than 45 is a good practice. The ADA also recommends that any person who has a body mass index (BMI) of 25 and at least one additional risk factor.
Diabetes tests that healthcare providers use include:
- A1C Test: When glucose is in the blood it attaches to the oxygen-carrying substance, hemoglobin, forming what scientists call “glycated hemoglobin.” The percentage of glycated hemoglobin or percentage of hemoglobin with blood glucose attached can be measure by the A1C test and that amount reflects your average blood glucose over the past two to three months. The higher your blood glucose levels have been, the higher your A1C will be.
- Random Plasma Glucose Test: This is a blood/plasma test administered any time of the day, regardless of when you last ate, measuring your level of glucose
- Fasting Plasma Glucose Test (FPGT): Just as the name applies, this is a blood/plasma test administered when you have been fasting (for at least 8 hours), measuring your level of glucose.
- Oral Glucose Tolerance Test (OGTT): This test involves fasting for eight hours after which your blood glucose level is measured. You then drink a special solution containing 75 grams of glucose and your blood glucose level is measured again two hours later. This test can be used for all forms of diabetes and has been shown to be more sensitive than the FPGT; however, it is more time consuming and, thus, less convenient. This is the primary test that obstetricians use for testing pregnant women for gestational diabetes and is typically administered between the 24th and 28th week of pregnancy. In some cases, an obstetrician will first administer a glucose challenge test where the mother will drink a glucose solution and have her glucose level checked one-hour level. If it is abnormal, she will then be scheduled for an OGTT.
A more recently recognized condition, which is on the rise, is called prediabetes. People with prediabetes have blood glucose levels that are higher than normal but not high enough to be classified as diabetes. These elevated blood glucose levels, as in type 2 diabetes, are the result of insulin resistance. These individuals have an increased risk of developing type 2 diabetes; in fact, many go on to develop type 2 diabetes within 10 years of being diagnosed with prediabetes.
Insulin is the mainstay of treatment for all type 1 diabetics; some, but not all type 2 diabetics will require insulin therapy as well. Insulin is produced by the beta cells found within groups called islets in the pancreas. It facilitates the uptake of glucose from the blood into cells so that the glucose can be used for energy.
In type 1 diabetes, the beta cells stop producing insulin. In type 2 diabetes, the cells stop responding to the effect of insulin and the beta cells often cannot produce enough to overcome this resistance. Some people with type 2 diabetes require insulin and some do not, but all people with type 1 diabetes must have insulin treatment. Because enzymes in our GI tract break insulin down and render it ineffective, insulin must be injected into the fatty tissue under the skin in order to get it into the blood stream.
If you are a type 2 diabetic, there are a variety of other medications your healthcare provider may prescribe for you, either as single therapy, in combination with insulin, or in combination with another oral medication. Each group of drugs has a unique mode of action, but the net effect of each is to lower blood glucose levels.
- Biguanides: Biguanides are a group of drugs that decrease the amount of glucose released from the liver. The most commonly prescribed oral medication for type 2 diabetes, metformin, is a biguanide.
- Thiazolidinediones: Thiazolidinediones, like biguanides, help reduce glucose release from the liver but also enhance insulin’s effect in fat and muscle tissue. The two thiazolidinediones on the market as of October 2015 are pioglitazone (ACTOS) and rosiglitazone (Avandia). Rosiglitazone has been linked in some studies to an increased risk of heart attacks and heart failure and is under review by the FDA but has not yet been pulled off the market.
- Sulfonylureas: Sulfonylureas work by stimulating the beta cells of the pancreas to secrete more insulin. There are first and second generation sulfonylureas. The only first generation sulfonylurea still prescribed is Chlorpropamide (Diabinese). The second generation sulfonylureas are glipizide (Glucotrol and and Glucotrol XL), glyburide (Diabeta, Micronase), and glimepride (Amaryl).
- Meglinitides: Meglinitides also stimulate the pancreas to secrete more insulin. Repaglinide (Prandin) and nateglinide (Starlix) are the meglinitides available today.
- DPP-4 inhibitors: Our intestinal cells produce a hormone called glucagon-like peptide-1 or GLP-1. GLP-1 promotes insulin secretion from the beta cells and also lowers the amount of glucose produced by the body. Some evidence suggests that it might also promote beta cell proliferation. GLP-1, however, is quickly broken down in our bodies by an enzyme called DDP-4. DDP-4 inhibitors, like sitagliptin (Januvia), saxagliptin (Onglyza), linagliptin (Tradjenta), and alogliptin (Nesina), block the action of this enzyme, thereby allowing GLP-1 to remain active longer, and ultimately aid in lowering blood sugar levels.
- SGLT-2 inhibitors: As blood is filtered through our kidneys, a molecule called sodium-glucose transporter 2 (SGLT-2) promotes reabsorption of glucose back into the blood. SGLT-2 inhibitors like canagliflozin (Invokana) and dapagliflozin (Farxiga) block the action of SGLT-2, thereby allowing the elimination of excess glucose into the urine and the lowering of blood glucose levels.
- Alpha-glucosidase inhibitors: Alpha-glucosidase inhibitors like acarbose (Precose) and miglitol (Glyset) work by slowing the breakdown of some carbohydrates (a source of glucose) in our intestines.
- Bile acid sequestrants: These drugs were initially used just to lower cholesterol levels, particularly LDL levels. Although it is not clearly understood why, researchers have found that they also lower glucose levels.
- Bromocryptine mesylate: This drug helps to increase the levels of the neurotransmitter dopamine. Although the mechanism is poorly understood, dopamine appears to have a positive effect on glycemic control.
The benefits of a healthy diet are many-fold. Most experts agree that a diet rich in fruits, vegetables, lean proteins, and whole grains (and therefore fiber, minerals, and vitamins) is better than one high in fat and sugars. A healthy diet can help with weight loss, improved glucose levels, improved cholesterol levels, and reduced stroke and cardiac disease risk.
There is no one perfect diabetic diet. Often your healthcare provider will refer you to a registered dietician who can help determine the best eating plan for you. Since certain foods, particularly carbohydrates, can raise your blood glucose levels more than others, dietitians may have you employ a plan that allows you to keep track of how many of those foods you consume.
- Carbohydrate counting: Carbohydrates, particularly simple carbohydrates like sugar or syrup, are foods that influence your blood glucose levels. The amount of carbohydrate a person with diabetes should eat varies by individual. It depends on how severe their diabetes is, what types of diabetes medications they are taking, and how active or inactive they are. With carbohydrate counting, a dietician will help you determine how many grams of carbohydrate you should have with each meal (an example, for some people with diabetes, 45- to 60-grams per meal is optimal). Packaged foods have labels indicating the amount of carbohydrate in each serving. The amount of carbohydrate in unpackaged foods can be determined with your dietician or estimated based on serving size using nutrition guides.
- Glycemic Index (GI): Some carbohydrates raise blood glucose levels more than others. The glycemic index is a way to compare how much a food will raise your blood glucose compared with the standard of how pure glucose or white bread raises your blood glucose. The higher the glycemic index of a food, the more likely it is to raise your blood glucose level. A high GI is considered to be 70 or above (examples are pasta and crackers), a medium GI is 56-69 (examples are brown rice and quick oats), and a low GI is 55 or less (examples are non-starchy vegetables and legumes). Click here to see University Health News’ Glycemic Index Chart.
Exercise has several beneficial effects in diabetes management. Exercise can both increase your body’s sensitivity to insulin and increase your cells’ ability to allow glucose in and to use it for energy whether insulin is present or not.
You should, however, consult your doctor before beginning a new exercise regimen to determine what is safe for you. Additionally, frequent glucose monitoring may be necessary to determine how different forms of exercise affect your blood glucose levels so that you can maintain safe blood glucose levels.