Diabetes mellitus is the collective name for a group of diseases associated with hyperglycemia (high levels of blood glucose) caused by defects in insulin p- duction, insulin action, or both. About 6. 2% of the US population (17 million people) have diabetes mellitus. It is the leading cause of kidney failure, bli- ness, and amputations. It is also a major risk factor for heart diseases, stroke, and birth defects. Diabetes Mellitus: Methods and Protocols provides a state-of-the-art account of the experimental methodology for studying the molecular defects leading to diabetes mellitus, both at the molecular and biochemical levels. The chapters cover a wide range of topics written by experts in their respective fields and are organized in two sections: Insulin Production and Insulin Action. The detailed experimental protocols presented, including the notes of interest, provide a very useful tool for basic researchers and clinicians for investigating and treating this disease. Each chapter starts with an introduction to a specific technique and explains its application in the field of diabetes research. Following the list of materials, a detailed description of the technique is presented in the methods section in a way that enables the successful execution of the protocol. The Notes section at the end discusses the pitfalls of the technique and alternative approaches. I am grateful to the numerous scientists who have contributed to this volume by writing both highly detailed and understandable chapters.