POSTURAL hypotension is considered the most dramatic clinical manifestation and hallmark of diabetic autonomic neuropathy.
1,2 In patients with diabetes, autonomic neuropathy with abnormal cardiovascular reflex tests has been associated with increased mortality from unexpected sudden death and renal failure.
3,4 However, there is no uniform criterion for postural hypotension that may be symptomatic or asymptomatic.
5 Although postural hypotension is most commonly defined as a drop of 20 mm Hg or more in systolic blood pressure from the lying posture to the upright posture,
6-11 the lack of symptoms associated with postural hypotension raises a question about the clinical value of this definition. It is reasonable to define postural hypotension as a particular decline in blood pressure that can predict a poor outcome.
10 A study of the Hypertension Detection and Follow-up Program
6 revealed that a decline of 20 mm Hg or more in systolic blood pressure after standing was associated with a high 5-year mortality rate, which indicated a poor prognosis for patients with diabetes complicated with hypertension. Epidemiological evidence also suggested that postural change with a decrease of 20 mm Hg or more in systolic blood pressure was a significant risk factor for fall and syncope.
7,8 Furthermore, a drop of more than 20 mm Hg in postural systolic blood pressure was a risk factor for symptomatic occlusive cerebrovascular disease.
9 Therefore, Lipsitz
10 thought that postural hypotension with a decline of 20 mm Hg or more in systolic blood pressure on standing should be used to define a potentially dangerous hypotensive response.