LOS ANGELES -- Insulin grown in plants has been shown to relieve diabetes in mice, according to a new study.

Diabetic mice showed signs of recovery after they were treated with insulin grown in plants, showed the study, conducted by a research team at the University of Central Florida.

By the end of the study, the diabetic mice had normal blood and urine sugar levels, and their cells were producing normal levels of insulin.

These results and prior research indicate that insulin capsules could someday be used to prevent diabetes before symptoms appear and treat the disease in its later stages, said biochemist Henry Daniell, who led the study.

Daniell has since proposed using lettuce instead of tobacco to produce the insulin because the crop can be produced cheaply and avoids the negative stigma associated with tobacco.

Capsules of insulin produced in genetically modified lettuce could hold the key to restoring the body's ability to produce insulin and help millions of Americans who suffer from insulin-dependent diabetes, said the study.

Insulin-dependent, or Type 1, diabetes is an autoimmune disease in which the body's immune system attacks and destroys insulin and insulin-producing beta cells in the pancreas. Insulin is a hormone that is needed to convert sugar, starches and other food into energy.

Insulin typically is given through shots and not pills so the hormone can go straight into the bloodstream.

In Daniell's method, plant cell walls made of cellulose initially prevent insulin from degrading. When the plant cells containing insulin reach the intestine, bacteria living there begin to slowly break down the cell walls and gradually release insulin into the bloodstream.

Though produced in lettuce, the insulin would be delivered to human patients as a powder in capsules because the dosage would need to be controlled carefully.

The National Institutes of Health provided 2 million U.S. dollars to fund the study. The findings are reported in the latest issue of Plant Biotechnology Journal.

If human trials are successful, the impact of the research could affect millions of diabetics worldwide and dramatically reduce the costs of fighting a disease that can lead to heart and kidney diseases and blindness.

About 20.8 million children and adults in the United States, or about 7 percent of the population, have Type 1 or 2 diabetes, according to the American Diabetes Association.