The manifestations of diabetic autonomic neuropathy (DAN) are manifold affecting all systems and organs innervated from autonomic system, but cardiovascular, urogenital, gastrointestinal, pupillomotor
, thermoregulatory, and sudomotor systems are the most important.
Autonomic symptoms involve the cardiovascular, urogenital, gastrointestinal, sudomotor, and pupillomotor
Damage to any part of the parasympathetic (afferent) visual pathway interferes with the input of light to the pupillomotor
(30) The reason for this is that the pupillomotor
fibres lie along the outer layer of the third nerve, but an ischaemic lesion affects the centre of the fascicle, sparing the pupillomotor
fibres and leaving the pupil unaffected.