Ultrastructure of muscle biopsies in recent, short-term and long-term juvenile diabetes.

Muscle biopsies from juvenile diabetics were studied by electron microscopy and the results correlated to earlier published light microscopical abnormalities of the same biopsies. A total of 32 striated muscle biopsies from 29 juvenile recent, short-term and long-term diabetes were examined. The ages ranged from 16 to 43 years with a diabetes duration from 1 week to 32 years. The material was compared with biopsies from healthy persons of the same ages. The electron microscopy revealed degenerative changes of the striated muscle fibres which signify a neurogenic atrophy. No myopathic alterations were found. The capillaries in both the recent and long-term diabetics showed an extremely pronounced pinocytosis indicating an increased metabolic activity. In the long-term group the intramuscular capillaries both from upper and lower extremities displayed a definitely thickened basement membrane. In the recent and short-term group the capillary wall alterations were debatable. The motor end plate in the recent diabetics revealed minimal alterations. Contrary to this the long-term group showed severe alterations with occasional disappearance of the nerve fibres.