This volume contains the edited proceedings of the Totts Gap Colloquium on Diabetes Mellitus, DILEMMAS IN DIABETES. The Collo­ quium, lasting two and a half days, was organized mainly as a dia­ logue among experts in the field with different disciplinary back­ grounds and, to some extent, differing points of view. The effort was to synthesize existing knowledge, reconciling disparate data and interpretation, and pointing up important areas of ignorance. Thus, the book should serve not only as a summary of recent information on diabetes, but as a reliable guide to the practicing physician as he wades through often conflicting etiologic dogmas and therapeutic practices. The Colloquium was made possible through the generous support of the Geigy Pharmaceutical Company and the conscientious and expert coordination of Mr. Oscar Swarth. The participants were: Dr. George F. Cahill, Boston, Massachusetts Dr. Harvey C. Knowles, Cincinnati, Ohio Dr. Rachmiel Levine, Duarte, California Dr. Lelio Orci, Geneva, Switzerland Dr. Norton Spritz, New York, New York Dr. Roger Unger, Dallas, Texas Dr. Robert Williams, Seattle, Washington Dr. Stewart Wolf, Galveston, Texas Dr. Arnold Lazarow and Dr. I. Arthur Mirsky were to have partici­ pated, but unfortunately were ill at the time of the meeting. Others in attendance included five medical students, especially selected from medical schools in the Philadelphia/New York area.