Diabetes mellitus (DM) is a metabolic disorder caused by insufficient or inefficient
insulin secretary response and it is characterized by increased
blood glucose levels (
hyperglycemia). DM is a heterogonous group of syndromes.
Glucose is the main energy source for the body, and in the case of DM, management of
glucose becomes irregular. There are three key defects in the onset of
hyperglycemia in DM, namely increased hepatic
glucose production, diminished insulin secretion, and impaired
insulin action. Conventional drugs treat diabetes by improving
insulin sensitivity, increasing
insulin production and/or decreasing the amount of
glucose in blood. This article provides a comprehensive review of the mode of action of most popular
hypoglycemic herbs, such as ginseng, bitter melon, fenugreek, banaba, Gymnema sylvestre and Coptis chinensis. The herbs act by increasing insulin secretion, enhancing
glucose uptake by adipose and skeletal muscle tissues, inhibiting intestinal
glucose absorption and inhibiting hepatic
glucose production. Although evidence from animals and humans consistently supports the
therapeutic effect of these phytomedicines, multicenter large-scale clinical trials have not been conducted to evaluate the safety and efficacy of these
herbal medicines and their interaction with conventional drugs when administered simultaneously.