Plasma Renin Activity in Diabetic Autonomic Neuropathy

Abstract

Postural changes in plasma renin activity were studied in 3 groups of age and duration-matched male diabetics (potent, impotent and with postural hypotension) and in non-diabetic control subjects. Those diabetic subjects with postural hypotension due to automatic neuropathy had no increase in plasma renin activity to the erect posture, whereas both the potent and impotent groups had similar plasma renin activity responses to the control subjects. There was a significant inverse correlation between the rise in plasma renin activity on standing and the postural drop in blood pressure (r = 0.476, P < 0.01) but no correlation with other tests of autonomic reflex function such as the Valsalva maneuver and blood pressure response to sustained handgrip. The lesion responsible for the postural hypotension is probably in the efferent sympathetic pathway. Neuropathy per se did not wholly explain the decreased postural plasma renin activity response. Diabetic nephropathy, with involvement of cells of juxtaglomerular apparatus, may also be implicated.