THE EFFECT OF AN ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR ON SKIN MICROVASCULAR HYPEREMIA IN MICROALBUMINURIC INSULIN-DEPENDENT DIABETES-MELLITUS

Patients with longstanding insulin-dependent (Type 1) diabetes mellitu s (IDDM) are reported to have microvascular complications in most capi llary beds. The microvascular hyperaemia of the skin in normoalbuminur ic and microalbuminuric IDDM patients and healthy volunteers was measu red with laser Doppler flowmetry. The effect of 3 and 9 months of trea tment with captopril, an angiotensin converting enzyme inhibitor, on h yperaemia in the microalbuminuric patients was studied. Mean (+/-SD) p retreatment duration of skin postocclusive reactive hyperaemia was lon ger in microalbuminuric than in both normoalbuminuric patients and hea lthy volunteers (118.2 +/- 34.4 vs 57.8 +/- 16.0 vs 63.3 +/- 18.3 sec, respectively, p < 0.00001). After 3 and 9 months of captopril treatme nt the prolonged hyperaemia was shortened to 78.6 +/- 45.6 s (p < 0.01 ) and 62.3 +/- 55.6 s (p < 0.03), respectively. Urinary albumin excret ion decreased from 63.9 +/- 43.5 to 33.4 +/- 28.1 mg 24 h(-1) at 3 mon ths treatment (p < 0.002) and 43.1 +/- 38.5 mg 24 h(-1) at the end of the study period (p < 0.02). A positive correlation between changes in urinary albumin excretion and the shortening of the skin postocculsiv e reactive hyperaemia was found. Blood pressure remained in the same r ange throughout. These results show that captopril affects skin blood flow, independent of its hypotensive effect. This action may reflect t he influence of angiotensin converting enzyme inhibitor on vascular be ds other than those of the kidneys.