The pancreatic islet organ in diabetes of late onset was found to be characterized by a striking regularity, except when the islets were hyalinized (Hellman 1961 a). The volumetric islet distribution in these cases showed the same mathematical relationship to the islet diameters as previously had been found to be valid for non-diabetics (Hellman 1959 a, b).

Patients developing diabetes during the growing period have low total weight of B cells, whereas those developing diabetes after maturation have higher volumes (Maclean & Ogiluie 1955). Besides diabetes of early onset, insuloma and acromegaly are examples of endocrine disorders in which morphological islet changes are reported to occur (Hultquist 1946; Ferner 1951: Simpson 1959). Hence it seems useful to have knowledge of the size frequency distribution of the islets also in these cases and compare the findings with those in diabetes of late onset and in non-diabetics. The results of such an analysis is presented in this paper.