RELATIONSHIP BETWEEN AUTONOMIC FUNCTION AND PROGRESSION OF RENAL-DISEASE IN DIABETIC PROTEINURIA - CLINICAL CORRELATIONS AND IMPLICATIONS FOR BLOOD-PRESSURE CONTROL

The objective of this study was to test the relationship between neuro logic and microvascular complications of type 1 diabetes mellitus. It was hypothesized that the mechanisms operative in autonomic dysfunctio n seen in diabetic patients with microangiopathy play a role in the ra pidity of progression to renal failure. Twenty-six type 1 diabetic pat ients with proteinuria were studied with computerized monitoring of he art rate variation during timed ventilation, assumption of upright pos ture, and Valsalva maneuver and with 24-h ambulatory blood pressure mo nitoring at baseline. Renal function was evaluated over the ensuing 12 months of intensive insulin therapy Blood pressure was treated so as to achieve consistent 24-h readings <140/90 mm Hg. Angiotensin convert ing enzyme inhibitors were the preferred antihypertensive agents. Seri al serum creatinine concentrations were compared using repeated measur es analysis of variance. Over 12 months there were no significant seru m creatinine changes for any autonomic test group with normal results at baseline. Groups with abnormal autonomic results at baseline demons trated statistically significant increases in serum creatinine over 12 months compared to their baseline. Of the tests, Valsalva separated g roups of patients with similar degrees of baseline renal impairment Ea ch of the sympathetic plus Valsalva combinations demonstrated a signif icant difference in progression of serum creatinine increase over 12 m onths. In each instance, if both sympathetic and Valsalva results were abnormal, there was a statistically significant increase in serum cre atinine over 12 months when compared to groups in which one or both te st results were normal. There is a relationship between autonomic func tion and the progression of renal dysfunction. The inability to vary t he heart rate to a Valsalva maneuver identifies a degree of parasympat hetic dysfunction that permits unopposed sympathetic tone, heralding m ore rapid renal destruction. A simple inexpensive bedside laboratory t est discerned a relatively low-risk group of diabetic patients with pr oteinuria that demonstrated no deterioration in renal function over 12 months. When the Valsalva maneuver was markedly abnormal the presence of a mean arterial pressure >100 mm Hg was associated with a greater likelihood of rapid renal deterioration. This group at higher risk of renal deterioration should undergo aggressive lowering of mean arteria l blood pressure to <95 mm Hg. (C) 1998 American Journal of Hypertensi on, Ltd.