Xiaoke
tea is consumed as a traditional herbal treatment for
diabetes mellitus in China. An aqueous extract of Xiaoke (1 g of dried
plant preparation in 64 ml of water), supplied ad lib in place of
drinking water during the induction and development of
streptozotocin diabetes in mice, reduced (about 30%) plasma
glucose concentrations by 25 days. The
polydipsia and
hyperphagia of the
streptozotocin diabetic mice were also reduced by Xiaoke, and the effects lapsed
after treatment was withdrawn. Xiaoke did not significantly alter plasma
insulin concentrations. Consumption of the Xiaoke extract by
insulin-treated diabetic BB/E Wistar rats did not affect glycaemic control or body wt. When
insulin treatment was reduced and discontinued, Xiaoke failed to prevent the progression of severe hyperglycaemia and
weight loss. The results suggest that the slowly generated antihyperglycaemic effect of Xiaoke in
streptozotocin diabetic mice may involve an extrapancreatic effect on food intake,
glucose production or
glucose clearance. However, as evidenced in BB/E rats, Xiaoke does not substitute for
insulin in the absence of endogenous insulin secretion.