July 12, 2006

Study: Exercise decreases Insulin Resistance but does not improve blood sugar control

The "study of the day" reported by Diabtes in Control involved two groups of people with "mild" type 2 diabetes. One group exercised, the other exercised and took a drug, Acarbose, which is sold in the U.S. as Precose.

What it found was this: while exercise reduced insulin resistance in the group using exercise alone, as measured by various laboratory techniques, it made no difference in blood sugar control as measured by the A1c. Adding Acarbose improved both IR and blood sugar control.

Lost in the way the article is presented is the more important message here: that the usual advice to exercise your way out of diabetes is not going to do much for you unless you cut way down on your carb intake. I took Acarbose for years and as long as I had some second phase insulin response left, it pretty much acted like cutting 15 grams of carb out of a meal. Unfortunately, as my second phase weakened, Acarbose started to simply postpone the blood sugar spike, not eliminate it. This sounds great, but it's main side effect which is socially catastrophic gas for anyone who eats anything near a "normal" amount of carbs, make it unlikely to ever gain much public acceptance.

But getting back to the study: Since 99.5% of doctors will tell anyone with diabetes that if they only exercised more they'd get better control, this is an extremely important finding. Reducing your Insulin Resistance in a way that makes lab instruments happy but doesn't lower A1c is not going to do much for your health.

My feeling has long been that exercise is oversold as a diabetes remedy. My blood sugar deteriorated significantly during the year when I went to the gym almost every day. I ended up with pretty muscles, lousy blood sugar and repetitive stress injury in my feet from the treadmill which eventually made it harder to do any exercise at all.

There certainly are reasons to do exercise--improving strength, endurance, and cardiac capacity--but exercise is not the miracle cure for diabetes people think it is. Studies also show it doesn't do much for obesity unless it accompanies a rigid, long-term diet.

Try telling that to the people selling gym memberships!


Anonymous said...

It's possibly I'm about to just agree with you in other words, in which case, fine.

It seems to me that exercise does have value in improving blood sugar control. However, in some people, it very likely does not have DIRECT value in improving blood sugar control. Reducing insulin resistance is good, but if your beta cells are toast, obviously you still need insulin. But you might well be able to reduce dosage somewhat. An indirect value.

On the other hand, there are type 2 diabetics, at least, who do see substantial effects from _carefully controlled_ exercise. The logical followup to "eat to the meter" is "exercise to the meter, too." Personal observation suggests that there is a relatively narrow band of heart rate cardio that lowers my blood sugar. Less does nothing; more may in fact make it leap. (A friend who is a thin type 2, or perhaps a type 1.5, as they now sometimes say, finds this even more true in her case.) Weight training doesn't do a darn thing directly, but building muscle mass assists in fat reduction, etc, etc.

So I'm kind of agreeing and kind of not, I suppose. I think exercise is by and large a good thing, but as with every other element of good control, it should never be done blindly and very few sweeping generalizations about it are valid. Testing before and after just makes good sense. (But try telling some doctors that.)