Both type 1 diabetics and type 2 diabetics can experience a phenomenon known as insulin resistance. This metabolic defect is the underlying cause of type 2 diabetes, but it can also occur in type 1 diabetics, giving them in effect both type 1 and type 2 diabetes.
There are two kinds of exercise that usually help control diabetes:
- Aerobic exercise to the point of exhaustion, or
- Resistance exercise to the point of exhaustion.
There is a great deal of truth to the adage "no pain, no gain" for diabetics, but you don't have to work out so hard that you put your health at risk.
The kind of "aerobic" exercise (power walking, running, swimming, or using an elliptical trainer, for instance) that helps get blood sugar levels down involves at least short period of exercising so fast that one is out of breath. During that brief period that the muscles operate with minimal oxygen, they burn about 34 times as much sugar to make the same amount of energy they can make with oxygen. A short burst of exercise that leaves you out of breath will lower your blood sugar levels quickly.
Basically, if you do aerobic exercise hard enough that it becomes temporarily anaerobic, it will lower your blood sugar levels. But if you want just to walk around the block, and around the block, and around the block some more, about 1-1/2 hours of gentle exercise will at least burn fat.
Your muscle will sequester the nutrients it needs to reshape and rebuild itself by temporarily becoming about 50 times more sensitive than usual to insulin. The muscle absorbs glucose and water from the bloodstream to build its energy fuel glycogen, which also causes the muscle to "pump up." At the same time, it absorbs amino acids to remodel the muscle fibers that give it strength.
The combination of effects can dramatically lower blood sugar levels, but an individual muscle cannot go through this process more often that about every 48 hours—or even just every 72 hours if you are age 60 or older. If you work out every day, you need to work different muscle groups to get maximum benefit from the time you spend in the gym.
And as little as 5 minutes a day working out really hard may be all you need to keep diabetes under control. It's great to exercise more than that, but exercise for fun.