A look at supplements and alternative-medicine products.(Knight Ridder Newspapers)

_The product: Nature's Herbs Gymnesyl.

_The claim: The product carries no claims but is often touted as a natural treatment for diabetes.

_Key ingredient: Gymnema sylvestre, a large woody vine found in tropical forests of central and southern India.

_Price: $15.89 for 50 tablets.

_Other sources: A handful of other companies also offer versions of this product, which is generally available in major health food stores.

_How it works: Stemming from the tenets of Ayurvedic medicine _ a system of knowledge codified in ancient Hindu texts _ gymnema is thought to increase urine output as well as the number of cells that secrete insulin in the pancreas. Others suggest the plant may interfere with glucose absorption and thus have an effect on blood sugar.

_Scientific evidence: A few small-scale studies have been done on the efficacy of this herb, many of them in India by the same team of researchers. One very limited study looked at gymnema in addition to Western medications and found that some patients could decrease their drug dosage once they started on the herbal alternative. Another study, done in rats, found that gymnema was not as effective as another plant, Azadirachta indica, when it came to lowering blood sugar levels.