Forearm hemodynamics and responses to exercise in middle-aged adult-onset diabetic patients

Much of the difficulty in assessing the progress of diabetic angiopathy and effects of experimental modes of therapy arises from the lack of quick, simple, inexpensive, and noninvasive tests to perform on the circulatory system of human subjects. We report here on values obtained by the use of mercury-in-rubber strain gauge plethysmography on 15 middle-aged, adult-onset diabetics who had minimal clinical evidence of microangiopathy. Standard tests are described for assessing forearm vascular function at rest, during tonic exercise of the fingers, and after interrupted repetitive exercise of the fingers. When matched against a similar aged nondiabetic group, the diabetics had slightly higher forearm vascular resistance at each level of exercise, a marked reduction (approximately 50 per cent) in capillary filtration coefficient, which is believed to be related to vascular filtering surface area, and a slight reduction in venous capacitance at all levels of exercise. The method of mercury-in-rubber strain gauge venous occlusion plethysmography provides the clinician with a sensitive and inexpensive tool with which to follow the evolution of angiopathy in diabetic patients.