Narrator: This is Science Today. Dr. Ira Goldfine of the University of California, San Francisco is an expert in Type II diabetes, which occurs when the body becomes resistant to insulin -- leading to fatigue, nerve damage, hypertension and other medical problems. He says Type II is all too common, occurring in around three of every 100 people.

Goldfine: If you go into certain ethnic groups, particularly Native Americans, you may find 20 percent prevalence.

Narrator: The main cause of insulin resistance is obesity, which is on the rise.

Goldfine: Another form of resistance would be lack of exercise, sedentary behavior. Another cause would be hormonal excess such as steroid drugs, corticoid drugs used to treat allergies, growth hormone, adrenaline kinds of drugs.

Narrator: The good news is that all of these causes are reversible.

Goldfine: So if you reduce the obesity or increase exercise tolerance or remove the hormones that are in excess or the pregnancy terminates, then the resistance decreases and many individuals can compensate.

Narrator: For Science Today, I'm Steve Tokar.