DETECTION OF EARLY SYMPATHETIC CARDIOVASCULAR NEUROPATHY BY SQUATTINGTEST IN NIDDM

OBJECTIVE - To determine the role of the squatting test in the detecti on of early sympathetic neuropathy in patients with non-insulin-depend ent diabetes mellitus (NIDDM). RESEARCH DESIGN AND METHODS - Three gro ups of nonsmoking, nonobese subjects were studied: 10 healthy subjects , 10 NIDDM patients without autonomic neuropathy (AN), and 10 NIDDM pa tients with AN defined by the presence of a pathological deep-breathin g value. All subjects were given three postural tests: lying-to-standi ng, sitting-to-standing, and squatting test. Heart rate (HR) and finge r arterial pressure were recorded with a noninvasive technique. RESULT S - Blood pressure (BP) fall (expressed as decremental area) was not s ignificantly different among the groups at standing up after sitting o r lying. By contrast, a significantly greater BP drop occurred in NIDD M patients with AN (1,123 +/- 245 mm2) compared with NIDDM patients wi thout AN (460 +/- 232 mm2) or normal subjects (429 +/- 138 mm2, P < 0. 001). The HR increase after all the orthostatic maneuvers was smaller in diabetic patients with AN (P < 0.01) compared with that recorded in other groups. Significant correlations were observed between BP fall after squatting and either the expiration:inspiration ratio at deep br eathing (r = -0.77, P < 0.001) or the duration of diabetes (r = 0.76, P < 0.001). CONCLUSIONS - The intrinsic orthostatic load of the squatt ing test, which is greater than conventional postural maneuvers, makes the squatting test an easy and useful test to detect early orthostati c dysregulation in NIDDM.