by Christopher D. Saudek, M.D.,
Professor of Medicine, Johns Hopkins University School of Medicine,
President, American Diabetes Association (July 2001).
Steroids are commonly used in medicine, and their effects on blood sugar are often seriously underestimated. To give the bottom line first, steroids seriously increase the blood sugar level of people who have diabetes, and they cause or uncover diabetes in many people who don’t yet have it.
While there are several kinds of steroids, such as the ones used in muscle building (“anabolic or androgenic steroids”), in this discussion we are talking about the group called corticosteroids or glucocorticoids, exemplified by the medications hydrocortisone, prednisone or dexamethasone.
For people who don’t think every day about steroids, blood sugar, insulin, diabetes or steroids, a few basic comments may help:
Corticosteroids are essential hormones, made in the adrenal glands, and part of the “fight or flight” response that also includes adrenalin. Like many hormones, they must be present in the right amount: lack of corticosteroids (“Addisons disease”) and excessive corticosteroids (“Cushings disease”) are each fatal if left untreated.
Corticosteroids are also used quite often medically, not only as a replacement drug in the setting of Addisons disease but to take advantage of their strong effect in suppressing inflammation and suppressing various immune problems. So they are taken to treat many illnesses, from poison ivy to severe asthma to pemphigus. Doctors always want to use them in the lowest dose possible and for the shortest time possible, because the corticosteroids have significant side effects, collectively known as “Cushings syndrome.”
One strong effect of corticosteroids is that they counteract insulin. So let’s talk about insulin, since it, too, may be beyond your everyday experience: Insulin is another hormone we all have, unless we have type 1 diabetes. Made in the pancreas, insulin helps the body burn sugar for energy. Without enough insulin, the sugar accumulates in the blood, the blood sugar goes too high, and that is called diabetes.
So when corticosteriods counteract the effect of insulin, this means that whatever amount of insulin your pancreas makes normally, when you take steroids, it has to make a lot more to hold the blood sugar normal. If your pancreas is strong and able, it rises to the occasion and makes more insulin when your doctor prescribes steroids. Your blood sugar stays normal. But if your pancreas is not so strong (call it “insulin challenged”), it can’t put out enough insulin to overcome the resistance caused by the steroids, not enough to do the job of keeping blood sugar normal. That’s when the blood sugar goes up, and you have steroid-induced diabetes.
If you have ever had a cardiac stress test, you know that they look at your cardiogram when you are at rest and it may be fine. But then they want to know whether it stays normal when your heart is stressed by heavy exercise. In the same way, your pancreas may be fine normally, but not up to the stress of steroid treatment. Other such “stress tests” of the pancreas include pregnancy and, the most common, obesity. In each of these situations, the person may have diabetes caused by the stress (diabetes during pregnancy), that is removed by getting out from that stress (diabetes being cured by delivery of the baby).
Steroid-induced diabetes, then, is a sign that your pancreas is not entirely normal, that it may be fine when not challenged by steroids, but is limited when you do have to take the steroids. Steroids are a “stress test” for the pancreas.
The symptoms of steroid-induced diabetes are the same as when diabetes is caused by any other problem: thirst, frequent urination, and unintentional weight loss. Or, the doctor may pick it up by doing a blood glucose test (over 125 mg /dl when you have fasted over eight hours being diabetic.)
Also, the management of steroid-induced diabetes may be similar to the management of other causes of diabetes: a more healthy diet, pills or even insulin. But the good news is that when the dose of steroids is reduced or they are stopped altogether, the diabetes may well go away. Having had diabetes once during steroid treatment, though, your pancreas has declared itself borderline. You are at much higher risk of getting it again later, especially if you start steroids again.