Re: Do diabetics have irregular blood pressure?

May we quickly review the factors leading to the blood pressure regulation?
Basically, blood pressure results from the interaction of two parameters. 
the first one is the volume of blood in the vessels (it is called 
volhemia), the second is the vascular tone (when increased, the arteries 
are narrowed, and the pressure inside increases).
Regarding diabetes, you are right in stating that an elevation of sugar 
level in the blood increases the osmolarity. But this leads to the 
opposite. When osmolarity increases, the kidney lets more fluid escape 
(urine output is greater), and this leads to dehydratation and eventually 
shock with a drop in the blood pressure. This is a basic regulation of 
volhemia, and kidney regulation is a very strong one (try drinking one 
liter of water, you will not undergo headhache, a symptom of high blood 
pressure, I guess you will quickly need a quiet place...).
But diabetic people have an impairement on their blood pressure, and 
especially what we call orthostatic hypotension, i.e. a marked drop in 
arterial blood pressure when you sit up. This impairement is due to a 
nervous disease (we call it diabetic neuropathia) generated by a chronic 
elevated arterial sugar level.

Hope this helps


Luc A. Ronchi, MD
Ped Anesthesia
Hopital de Saint Nazaire, France