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

Both endothelial cell function and autonomic function are influenced by age. However, the interrelationships between the 2 have not been carefully examined.

Thirty nondiabetic control subjects (C) and 25 subjects with type 2 diabetes (D) participated. Endothelial cell function was assessed by 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 up position. A laser Doppler flow imager was used to assess skin flows during the tilting phase.

For endothelial function, the average BF of C increased 2.24+/-0.64 cc/100 gm tissue/minute at rest to 26.8+/-4.9 cc/100 gm tissue per minute post occlusion. D subjects had resting BF of 0.8 cc/100 gm tissue per minute with an increase to an average of 8.1+/-3.64 cc/100 gm 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.

The data suggests that diabetes alters both the endothelial and autonomic function.