Diabetes mellitus represents one of the most frequent and serious clinical syn dromes in contemporary medicine. Since the end of the nineteenth century, the endocrine pancreas has been implicated in the pathogenesis of this disease. Several pathologists of the twentieth century detected various lesions and mor phologic alterations in the pancreatic islets of diabetic patients, but the patho physiologic basis of their findings remained long obscure. The systematic mi croscopic work of WILLY GEPTS clarified the views and related the variety in histopathology to differences in origin, duration...