The effects of type 2 diabetes and aging on vascular endothelial and autonomic function

Background: Both endothelial cell function and autonomic function are influenced by age. However, the interrelationships between the 2 have riot been carefully examined. Material and Methods: Thirty nondiabetic control subjects (C) and 25 subjects with type 2 diabetes (D) participated. Endothelial cell function was assessed 4 minutes of occlusion of the brachial artery followed by measurement of blood flow (BF) immediately post. occlusion. To assess autonomic reactivity, subjects were exposed to a 32 degrees C room for 30 minutes and a tilt. table elevated subjects from the horizontal to the 45 degree head lip position. A laser Doppler flow imager was used to assess skin flows during the tilting phase. Results: For endothelial function, the average BF of C increased 2.21 +/- 0.64 cc/100 gm tissue/minute at rest to 26.8 +/- 4.9 cc/100gm tissue per minute post occlusion. D subjects had resting BF of 0.8 cc/100gm tissue per minute with an increase to an average of 8.1 +/- 3.64 cc/100gm tissue per minute post occlusion. In both, aging was associated with lower resting and post occlusion BF. However, D had lower BF than the controls. For D, both the resting flows and reduction in flows during tilting were less than the controls. Both groups followed a parallel decrease in flow with aging. Autonomic reactivity (ratio of BF to the skin in the vertical to horizontal posture) was 0.4 +/- 0.27 for the controls and 0.72 +/- 0.09 for the subjects with diabetes. Conclusions: The data suggests that diabetes alters both the endothelial and autonomic function.