Book excerpt: Medicinal plants are a source of potential therapeutic compounds. Phytotherapy can give patients long term benefits with less or no side effects. Phytotherapy in the Management of Diabetes and Hypertension is a book series which emphasizes the biochemistry behind diabetes mellitus and hypertension, along with the control or remediation of these conditions through cost effective, safe and easily-adaptable methods validated by scientific research. This is the fourth volume of the series which features reviews on selected natural products used to treat diabetes and hypertension. This volume brings 6 chapters contributed by 14 researchers that cover general updates on diabetic phytotherapy, circumin, and the medicinal use of olive leaves, passion fruit and spiral gingers in the treatment of diabetes and hypertension. Each review covers different plant species or medicinal agents where applicable, providing readers essential information about their role in the treatment of diabetes and hypertension. Both academic and professional pharmacologists as well as clinicians will find comprehensive information on a variety of therapeutic agents in this volume.