Ultrastructural analysis of mitochondria-associated membranes in lymphocytes of newly diagnosed type 2 diabetes mellitus

There is a growing number of evidence that mitochondrial dysfunction plays an important role in pathogenesis of diabetes mellitus. At near-contact sites between mitochondria and the ER, membranes of these organelles are juxtaposed within distance of 50 nm, referred to as mitochondria-associated membranes (MAMs). The aim of this study was to carry out an ultrastructural analysis of mitochondria-associated membranes in peripheral blood lymphocytes of patients with newly discovered type 2 diabetes mellitus and compare them with the same structures in lymphocytes of healthy persons. Transmission electron microscopy was employed to study peripheral blood lymphocytes from newly diagnosed patients not undergoing any metabolic therapy or antidiabetic medications, as well as from healthy persons. Lymphocytes of diabetic patients had more mitochondria, albeit with unchanged mitochondrial fractional volume, and more MAMs compared to lymphocytes from healthy individuals. An increase in the number of mitochondria and MAMs in peripheral blood lymphocytes could reflect disturbed mitochondrial dynamics and immunological changes that are present in patients with type 2 diabetes mellitus. In conclusion, the results obtained in our study emphasize the possible role of mitochondria and mitochondria-associated membranes in the metabolic changes of type 2 diabetes mellitus.