The authors of a report published in the journal Diabetes Care explain that Caiapo is commercialized in Japan as a dietary supplement used to help prevent and control type 2 diabetes. It is derived from a variety of sweet white potato that grows in mountainous regions.

Dr. Bernhard Ludvik, of the University of Vienna Medical School, in Austria, and colleagues examined the tolerability, effectiveness and mode of action of Caiapo on metabolic control in 61 patients with type 2 diabetes. The subjects were randomly assigned to receive 4 grams of Caiapo or a placebo, each given once daily for 12 weeks.

The researchers report that levels of hemoglobin A-1c (HbA1c), used to measure excess blood sugar, decreased significantly from 7.21 percent to 6.68 percent after treatment with Caiapo. In the placebo-treated patients, HbA1c remained unchanged.

Decreases in fasting blood sugar levels (from 143.7 to 128.5 milligram per deciliter) were observed in Caiapo-treated patients, while no significant change was observed in those who received placebo.

On glucose tolerance testing, patients in the Caiapo group also had significantly decreased 2-hour glucose levels compared with the placebo patients.

"At the end of the treatment period, cholesterol levels in the Caiapo group were lower than those in the placebo group," Ludvik and colleagues report.

No significant adverse events were observed with Caiapo.

"Thus," they conclude, "the nutriceutical Caiapo seems to be a useful agent in the management of type 2 diabetes."