Urinary angiotensin-converting enzyme activity in type 2 diabetes mellitus: its relationship to diabetic nephropathy.

Urinary angiotensin-converting enzyme (ACE) and urinary N-acetyl-beta-D-glucosaminidase (NAG) were measured after a 5-year interval in 38 non-azotemic type 2 diabetic patients. Of these patients at baseline, 16 had nil nephropathy, 15 had incipient nephropathy, and 7 had overt nephropathy. During the follow-up, 6 and 1 of the 16 patients with nil nephropathy developed incipient and overt nephropathy, respectively. Four of the 15 patients with incipient nephropathy progressed to overt nephropathy. The 7 patients with overt nephropathy continued to have overt nephropathy, with slight azotemia in one. Urinary ACE and NAG levels were normal at baseline and showed no significant elevations at follow-up in the patients with nil nephropathy, no significant changes in baseline and modest elevations at follow-up in the patients with incipient nephropathy, and high at baseline and marked elevations at follow-up in the patients with overt nephropathy. In all patients, urinary ACE during the follow-up was positively correlated with urinary albumin or NAG, but not with glomerular filtration rate. Urinary ACE may be of poor prognostic value for the follow-up of diabetic patients, which is at variance with urinary albumin.