Abstract
Long recognized as a cause of cardiovascular and gastrointestinal and genitourinary tract dysfunctions in patients with diabetes mellitus, there is substantial evidence that diabetic autonomic neuropathy plays a fundamental role in the pathogenesis of two clinical metabolic syndromes in patients with diabetes mellitus: hypoglycemia unawareness and defective glucose counterregulation.1-3 Hypoglycemia unawareness is clearly a neurologic syndrome. It is characterized by the absence of warning symptoms such as sweating, palpitations, and arousal with a decline in the plasma glucose concentration, resulting in neuroglycopenia as the initial and only manifestation of hypoglycemia. Its prototype occurs during experimental hypoglycemia in patients who have suffered cervical spinal cord transections. In patients with diabetes mellitus, hypoglycemia unawareness is associated with, and probably results from, a deficient sympathochromaffin response to plasma glucose decrements.4 It is generally thought that the absence of warning symptoms increases the frequency of severe iatrogenic hypoglycemia in patients with hypoglycemia