This invention relates to plant extracts containing nutritionally beneficial or medicinally active compounds. Some of these extracts, or the purified compounds contained therein, may be used for the nutritional support, prevention, treatment, or possible cure of various metabolic and other diseases and disorders in human beings and animals, including type 1 and type 2 diabetes, by regulating insulin signaling. This regulatory effect may include modulations of the levels and/or activity of the Insulin Receptor (IR), the Insulin-like Growth Factor (IGF) Receptor, and/or the Insulin Receptor Substrate (IRS) proteins in cells and tissues in the body.