Blood Glucose Control Determines the Renal Haemodynamic Response to Angiotensin Converting Enzyme Inhibition in Type 1 Diabetes

Elevation of glomerular filtration rate (GFR) is a feature of diabetes mellitus in humans and in animal models. Angiotensin II has been implicated as a mediator of GFR in diabetes. The acute effect of inhibition of angiotensin converting enzyme with captopril on renal haemodynamic and endocrine parameters was therefore studied in 14 normotensive male Type 1 diabetic patients, and the responses compared with those in five normal male control subjects. Following captopril 12.5 mg orally the diabetic patients exhibited an acute fall in GFR from 122 ± 3.8 to 113 ± 4.5 ml min−1 1.73‐m−2 (p < 0.02) and a rise in renal plasma flow (RPF) from 670 ± 57 to 797 ± 46 ml min−1 1.73‐m−2 (p < 0.01) which resulted in a fall in filtration fraction. This did not occur in normal control subjects. Natriuresis occurred only in normal control subjects. There was no change in urinary excretion of PGE2 or kallikrein in either group but excretion of 6‐keto‐PGF1α fell in the diabetic patients. There was a significant correlation between glycosylated haemoglobin and baseline RPF (rs = −0.79, p < 0.001) and filtration fraction (rs = 0.83, p < 0.001) that persisted when the change in these variables following captopril was analysed. Our results are compatible with the response to ACE inhibition in diabetic patients being secondary to inhibition of angiotensin II and suggest that this response may be related to blood glucose control. 1990 Diabetes UK