Antidiabetic effects of white skinned sweet potato (Ipomoea batatas L.) (WSSP) and
troglitazone, an
insulin sensitizer, were investigated.
Hyperinsulinemia in Zucker fatty rats was reduced by 23%, 26%, 60% and 50%, respectively, 3, 4, 6 and 8 weeks after starting the
oral administration of WSSP. Similar results were obtained with
troglitazone. In the
glucose tolerance test after 7 weeks of treatment, increases in
blood glucose levels after
glucose loading were inhibited by the administration of WSSP.
Glucose tolerance was also improved. Blood triacylglyceride (TG) and
free fatty acid (FFA)
lactate levels were lowered by the
oral administration of WSSP. Similar effects on blood
insulin,
lipid and
lactate levels were observed after the administration of
troglitazone.
Body weight gain increased in the
troglitazone group, but not in the WSSP group, compared to the control group. In histological examinations of the pancreas of Zucker fatty rats, remarkable regranulation of pancreatic islet B-cells was observed in the WSSP and
troglitazone groups after 8 weeks of treatment. These results suggest that WSSP shows remarkable
antidiabetic activity and improves the abnormality of
glucose and lipid metabolism by reducing
insulin resistance.