The steady increase of diabetes mellitus among civilized nations and the extensive search for a prolonged acting insulin brought forth protamine zinc insulin for the treatment of the diabetic patient. In this book the existing literature on insulin and its longer acting substitutes is thoroughly reviewed. Any one acquainted with the subject knows how difficult this task is. This monograph, which appeared in the Swiss medical year book, can be highly recommended to research workers and clinicians who wish to be informed on the various aspects of insulin therapy. Its special usefulness lies in the extensive bibliography.