Ultrastructural morphometric analysis of insulin secretory granules in human type 2 diabetes.

We performed an ultrastructural morphometric analysis of insulin secretory granules in pancreatic beta cells from control and type 2 diabetic multiorgan donors. The volume density of insulin granules significantly (p < 0.05) reduced in beta cells from type 2 diabetic patients with respect to non-diabetic subjects, and this reduction was mainly attributable to a decrease in mature granules. On the contrary, no significant difference was observed in the volume density of docked granules between controls and type 2 diabetic patients. In addition, there was a significant positive correlation between the density volume of total insulin granules and stimulated insulin secretion in non-diabetic islets. In conclusion, we detected significant changes in the intracellular distribution of insulin secretory granules within the beta cell that might be related with the alterations in insulin secretion observed in type 2 diabetes patients.