December 1, 2010
By Jonathan Sackier
A patient presented to Aretaeus the Cappadocian, “Doc, I’m passing lots of urine!” “Aha!” said Aretaeus.“You have polyuria.” The unfortunate fellow asked, “What does that mean?” Aretaeus’ response? “It means you pass lots of urine!” Later named diabetes (“to pass through”) and divided into two types— insipidus, where the urine is tasteless (whoever heard of tasty urine?) and mellitus, meaning sweet, like honey. Why ancient doctors sipped urine is beyond me, but it created an industry—as L Lawliet of Japanese anime fame said: “Diabetes is a myth. It is nothing but a lie made up by doctors and dentists who want all the sugar to themselves.” If only that were true.
Have you ever eaten sweetbreads? If so, you have enjoyed the culinary pleasures of thymus and pancreas. Diabetes occurs when the pancreas, or “belly sweetbread”—which lies in front of the spine, behind and below the stomach—fails to make enough insulin, or when cells throughout the body are resistant to its effects. Insulin derives from insula, named for the pancreatic Islets of Langerhans that manufacture the hormone controlling glucose levels.
When I was at medical school (“Yes, son, we had electricity back then”) diabetes was classified as Type 1, occuring mostly in juveniles (juvenile onset diabetes) requiring insulin, and Type 2, in older obese folk, usually controlled with diet, exercise, oral drugs, and sometimes insulin (maturity onset diabetes). Genetics and other factors contribute, but with the obesity epidemic we are seeing more diabetics and many require insulin. In fact, about 24 million Americans have the disease, 57 million are prediabetic (see below) and 2 million join the ranks annually. Type 1 occurs at any age and Type 2 is being diagnosed ever younger—about 90 percent of diabetics are of this type.
Diabetic symptoms make sense when one understands what’s happening “under the hood.” As sugars are not processed properly they are expelled by the kidneys, osmotically dragging water along; this explains polyuria and why urine might taste sweet. With more urination, thirst increases and failure to properly metabolize causes fatigue, general ill health, blurred vision (glucose and water enter the lens, causing swelling), weight loss, and predisposition to bladder, skin, and other infections.
Such symptoms in the presence of obesity usually prompt the doctor to test the urine. Fasting blood glucose is another key test—between 70 and 99 mg sugar/100 ml of blood is considered normal, 100 to 125 mg suggests “pre-diabetes” or impaired glucose tolerance, and above that one has diabetes. A glucose tolerance test involves giving a sugar drink after the initial blood test, then drawing another sample two hours later. Below 140 mg you are in the clear, from 140 to 200 impaired tolerance, and above 200 mg the “D” word is heard. Sometimes diabetes manifests during pregnancy and on occasion this “gestational diabetes” clears up after giving birth.
Therapy is aimed at reducing obesity, simultaneously initiating a cautious exercise program, special diets, and monitoring portion sizes. In some patients oral medications are used, which increase insulin production, the body’s sensitivity to insulin, reduce the liver’s production of glucose, or interfere with carbohydrate absorption. Others need to use insulin, available in various strengths, durations of action, and modes of administration. All diabetics should monitor blood sugar frequently to prevent dangerous highs (hyperglycemia) and lows (hypoglycemia). While finger-prick testing is widely used, Hemoglobin A1C is also helpful; sugar adheres to red blood cell protein, allowing physicians to evaluate blood sugar level behavior over the past three months (4 to 6 percent is normal)
Especially when not tightly controlled, diabetes causes problems with eyes, skin, nerves, the heart, and other organs. Keeping healthy and regular check-ups are called for.
Gary Crump, AOPA director of medical certification, advised me about the FAA medical regulations regarding diabetes. When adequately controlled with diet and exercise, certification under Part 67 medical standards is possible, but if insulin or oral medications are utilized, flying privileges are suspended and a special issuance authorization is required.
Certain diabetic medications can lower blood sugar too much, or cause adverse side effects, so the FAA has dictated which meds can be used together. Treating diabetes with a single medication, such as one of the sulfonylureas (e.g., Glucatrol or Glynase) or metformin, requires a detailed status report from your treating physician, including hemoglobin A1C. Combination therapies exist, but check out AOPA’s online information to see if the medications your doctor wants to use are allowed.
Once issued a medical certificate, you must provide annual followup to the FAA and in cases involving oral agents only, your aviation medical examiner can reissue your new certificate if the updates on your condition and your A1C remain stable.
The mythic joke states that a diabetic walks into a bakery and asks: “What do you have that’s safe for diabetics?” The baker says, “Everything. As long as you don’t put it in your mouth.” Not true, but preventing obesity—one of the big risk factors—can stop you from having tasty urine.
Thank you to Dr. Martin J. Abrahamson, chief medical officer and senior vice president, Joslin Diabetes Center, Harvard Medical School, for his insights.
Jonathan M. Sackier has practiced medicine in the United States for the past 20 years.
Aviation Medical Examiner,
Pilot Health and Medical,
Special Issuance Medical
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