We evaluated baroreflexes in 58 diabetic and 15 control subjects by determining the latency of response between the end of a Valsalva maneuver (VM) and points on the resultant blood pressure and heart rate (HR) response curves. Prolonged latencies indicative of sympathetic dysfunction were demonstrated in 44% to 88% of diabetic subjects. The results challenge the view that sympathetic dysfunction cannot be detected before parasympathetic abnormalities are manifest. Baroreflex latencies reflected sympathetic dysfunction early in the course of diabetes, sometimes in patients with normal HR responses to deep breathing and to a VM.

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