The most prevalent endocrine condition, diabetes mellitus (DM), is characterized by underutilization of glucose, elevated blood sugar levels, and an ineffective or insufficient insulin secretory mechanism. DM is a severe health issue that affects 3% of the global population and 5% of the people in the US. Each year, it accounts for around 5% of all fatalities worldwide. Type 2 diabetes affects more than 90% of diabetic patients, whereas type 1 affects the remaining 10%. Today the management of diabetes without any side effects is still a challenge. Herbal drugs are prescribed widely because of their effectiveness, fewer side effects and relatively low cost. Numerous active principles produced from plants have proven to have anti-diabetic properties. Herbal treatments for diabetes have been used in patients with insulin-dependent and non-insulin-dependent diabetes, diabetic retinopathy, diabetic peripheral neuropathy, etc. Various plants can lower glucose production, promote glucose utilization, and combat secondary complications. This book will provide an updated, comprehensive resource of information on diabetes mellitus and its treatment by natural products. We believe this book will be of value to clinicians, biochemists, public health authorities, medical laboratory sciences technologists, biotechnologists, pharmaceutical and medical students, and fellows in training.