In the last decade, it has become increasingly evident that the clini- cal and morphologic changes underlying many of the complications of diabetes, including cataract formation, retipathy, nephropathy, neuropathy, and macrovascular disease, are preceded by a variety of disturbances of biochemical and physiologic origin. Dr. Cohen has recently written a superb mograph, entitled Diabetes and Protein Glycosylation: Measurement and Biologic Relevance, in which she thoroughly explores how enhanced nenzymatic glycosylation in uncontrolled diabetes underscores the pressing need for main- tenance of long-term euglycemia. In the present volume, The Polyol Paradigm and Complications of Diabetes, she reviews, in a most succinct and thorough manner, how ather biochemical mechan- ism, involving the polyol pathway, is involved in the pathogenesis of such diabetes complications as retipathy, neuropathy, nephropa- thy, and cataract formation. Dr. Cohen gives us a clearly written and comprehensive mo- graph, reviewing the chemistry of the polyol pathway and of the aldose reductase inhibitors, and the pathophysiologic significance of increased polyol pathway activity in a variety of tissues affected by Vlll Foreword diabetes mellitus. She insightfully describes the relationship of increased polyol pathway activity to altered metabolism of isitol- containing phospholipids and to changes in various tissue concentra- tions of myo-isitol. Finally, she provides us with a careful review of the existing experimental and clinical studies with a variety of different aldose reductase inhibitors that have been and are being performed in the hope of preventing or reversing long-term compli- cations of diabetes.