Urinary excretion of angiotensin-converting enzyme in NIDDM patients with nephropathy

Twenty-four-hour urinary excretion of angiotensin-converting enzyme (ACE) was investigated in relation to that of albumin and beta 2-microglobulin (beta 2M) in 25 non-insulin-dependent diabetes mellitus (NIDDM) patients without nephropathy, 13 NIDDM patients with incipient nephropathy, 18 NIDDM patients with overt nephropathy, and 14 nondiabetic subjects. NIDDM patients without nephropathy and nondiabetic subjects were similar in albumin, beta 2M, and ACE excretion. NIDDM patients with incipient nephropathy had elevated albumin excretion (P less than .01) and similar beta 2M and ACE excretion compared with nondiabetic subjects. On the other hand, NIDDM patients with overt nephropathy had elevated albumin, beta 2M, and ACE excretion compared with nondiabetic subjects (P less than .01). In all NIDDM patients studied, a positive correlation was found between ACE excretion and albumin excretion (r = 0.76, P less than .001) or beta 2M excretion (r = 0.52, P less than .01). These data suggest that elevated ACE excretion in NIDDM patients with overt nephropathy may be reflective of renal tubular damage.