London ? A pill that blocks the digestion of starch could prevent or delay the development of diabetes in those with slightly high blood sugar, a new study indicates.

Experts say more than 200 million people, including nearly 16 million Americans, are pre-diabetic and half will develop diabetes within 10 years. They predict a worldwide explosion by 2025 and say diabetes is likely to become the biggest epidemic ever.

Although exercise and healthier eating can delay or prevent diabetes for most people, some experts believe that because many people won’t heed advice about healthier lifestyles, drugs will be necessary.

A study published this week in The Lancet medical journal found that pre-diabetics who took starch-blocker pills cut by 25 percent their chances of progressing to diabetes, which is a leading cause of blindness, kidney failure, amputations and heart disease. It is the fourth-leading cause of death in the industrialized world.

Some people are born with diabetes, but the vast majority have Type 2 diabetes, which is acquired later in life. Diabetes is a disease in which the body does not produce or properly use insulin, a hormone that converts sugar, starches and other food into energy.

The drug tested in the study, acarbose, prevents the breakdown of sugar, so it is expelled from the body undigested and does not reach the bloodstream.

Acarbose, made by Bayer and sold as Precose in the United States and as Glucobay in Europe, has been approved for the treatment of diabetes for nearly 10 years. However, it is not widely used because of unwelcome side-effects diarrhea and flatulence.

The study, funded by Bayer, involved 1,400 people from nine countries who had pre-diabetes, known scientifically as impaired glucose tolerance.