by Peter J. Nebergall, PhD


One of the most prominent features of diabetes is its uniqueness. No two diabetics respond in exactly the same way to their food, insulin, or exercise, and no two individuals, even if they show the same glucose test results, will experience precisely the same complications. The disease is, by definition, unpredictable. Still, making allowance for surprises, we know the effects of more insulin, less insulin, more exercise, less exercise, more food, etc.

For most diabetics, most of the time, the "rules" work. "If I do this, or do not do that, I can expect this result." But there is a body of individuals for whom the rules do not appear to apply, and to them is often applied the adjective "brittle."

The problem becomes separating the truly "brittle" diabetics from the non-compliant, the poorly-controlled, or those whose unstable sugars have other explanations. Some have insisted that if all diabetics diligently practiced "tight control" (as described by the DCCT), none would be "brittle." They're partially right; the numbers would go down, but some diabetics can do everything right and still remain "brittle."

These are the diabetics, even practicing tight control, whose blood glucose level "over-reacts" to minute changes in diet, exercise, and/or insulin. These individuals experience unpredictable rises and swoops in blood glucose, within very short periods, as the result of very small departures from schedule. Small changes "break" their control, and they are thus said to be "brittle."

If you are practicing tight control, are in good compliance with your schedule, and are still experiencing rapid, out-of-proportion blood glucose changes, talk to your doctor. You (or more correctly your diabetes) may be "brittle," but your instabilities may well be a sign of some other problem.

Maybe You're Not Brittle

Many diabetics whose sugars seem to run unpredictably, "all over the map," have heard their diabetes described as "brittle." Sometimes it is; but there are other possible explanations, such as the dawn phenomenon, and the Somogyi Effect. If your sugars are unexpectedly high in the morning, one of these may be the explanation.

We all have our normal "sleep cycles." When the human body becomes used to a schedule, it releases hormones, including glucagon, into the blood on schedule, to help you wake up. Your sugars rise, in the expectation of activity. How many times have you opened your eyes, looked at the alarm clock, and found it was one minute short of going off? That hormone and blood sugar rise is the dawn phenomenon. It is very normal, and perhaps your morning glucose monitor test is catching it.

Problems come either when this response, the dawn phenomenon, fools you into thinking you need more insulin, when you don't, or when it gets out of hand, excessive, requiring you to readjust your diet/medication balance.

There is also the Somogyi Effect (named for the researcher who first described it in the 1930s). Your body naturally seeks balance, what the doctors call homeostasis, in all things, including blood glucose. After you eat, a healthy, non-diabetic pancreas will secrete more insulin, to bring the numbers back down. If you have a "low," your liver will release stored glucose, to bring you back up. But this "rebound" is imprecise; and when you have a low, and your body rebounds, it'll often take you way up into the high range. Then, if you happen to test your blood sugars, you'll see you're high, get worried, and perhaps add more insulin to bring your numbers back down. BUT--you're only high because you're having a rebound from a low, so that extra insulin just points you back into another low, which will likely trigger another rebound, making you think you're high again... You're not brittle; you're in the midst of the Somogyi Effect!

So what should you do about this vicious cycle? Slow down, and do some tests. Are you having unrecorded night-time "hypos?" If your early morning high is regularly preceded by a night-time low, treat the cause of that low; perhaps you need to lower your afternoon insulin dose, and/or add a bedtime snack. If you can eliminate the "low," you'll eliminate the body's rebound. You may need less insulin.

If your sugars are not running low at night (and a week's late-night tests should let you know), but you're too high in the morning, it could be the dawn phenomenon, and if it is, you may need more insulin. You can see how important it is to tell which phenomenon you're dealing with.

Real "brittle diabetes" doesn't follow patterns. Individuals who'se diabetes is "brittle" experience unpredictable, out-of-proportion rises and swoops in blood glucose, within short periods of time, as a result of very small deviations from schedule. Talk to your doctor, and to your health care team. They should help you set up an individualized testing program that will reveal what's going on--and then give you the tools to deal with it. Good luck!