The influence of amyloid deposits on the islet volume in maturity onset diabetes mellitus.

Pancreatic islet volumes of patients with and without maturity onset diabetes mellitus were estimated. The islet volume of the diabetic patients was 1.01 +/- 0.12 cm3 (SEM) and that of the non-diabetic patients 1.60 +/- 0.16 cm3 with considerable overlap between the two groups. Islet amyloidosis was found in all the diabetic and in 9 of the 15 non-diabetic patients. When the amyloid deposits were excluded, the islet volume of the diabetic patients was 0.89 +/- 0.10 cm3, while that of the non-diabetic patients was unchanged, 1.60 +/- 0.16 cm3. There was still some overlapping. Since amyloid deposits seem to destroy the B cell membranes, it was postulated that a comparison of the volumes of islets completely free of amyloid might give a more true picture of the quantitative islet alterations in maturity onset diabetes. It was found that this islet volume of the diabetics was only 0.41 +/- 0.05 cm3 and that of the non-diabetic patients 1.58 +/- 0.16 cm3. These values correspond better to the altered insulin secretion in maturity-onset diabetes mellitus.