Pathology and time relationship of peripheral nerve changes in experimental diabetes

Structural changes have been studied in peripheral nerves in streptozotocin-induced diabetic monkeys. Teased single nerve fibre preparations were most informative. Abnormalities were present in 32 of 58 nerves examined from 15 diabetic monkeys with varying degree of hyperglycaemia. The earliest change was an increase in the gap at nodes of Ranvier, seen 12 weeks after the diabetic state had been established. Well marked segmental demyelination was seen in distal nerves at 14-16 weeks. Later similar changes were seen in proximal, larger nerves. Evidence of remyelination was present at a later date. Wallerian degneration was seen in only 4 nerves. Changes in the myelin sheath were more prominant than axonal abnormalities at all times. There was no abnormality in the vasa nervorum and only a mild increase in endoneurial and perineurial fibrous tissue. A direct correlation was present between the extent and degree of pathology and both severity as well as duration of hyperglycaemia.