Prospective evaluation of urinary N-acetyl-beta-D-glucosaminidase with respect to macrovascular disease in elderly type 2 diabetic patients.
OBJECTIVE: To analyze prospectively the importance of urinary N-acetyl-beta-D-glucosaminidase (NAG), a marker for renal tubular function, in comparison with urinary albumin excretion (UAE), a marker for glomerular renal function, with respect to macrovascular disease in elderly patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: We followed 124 patients over a mean period of 7.0 +/- 0.5 years. At baseline, urinary NAG, UAE, age, diabetes duration, sex, blood pressure, lipids, and serum creatinine were determined. Also, history of myocardial infarction (MI), stroke, severe peripheral vascular disease (PVD), antidiabetic and concomitant medication, and smoking habits were recorded. After 7 years, patients were reevaluated, and a multivariate logistic regression analysis was used to test risk factors for significance in order to predict macrovascular disease. Subgroups of patients were analyzed with respect to severe macrovascular disease, with a separate analysis for surviving patients. RESULTS: Compared with known cardiovascular risk factors such as microalbuminuria and total cholesterol, urinary NAG was similarly associated with cardiovascular disease for the total cohort (P < 0.05). Analyzing the subgroup of 65 patients still alive after follow-up care, urinary NAG and UAE were significantly elevated at baseline and at the time of follow-up care in patients with MI and PVD, but not in those with stroke (P < 0.01). There was a positive predictive trend of NAG excretion for the development of MI and PVD in our patients (P = 0.07). CONCLUSIONS: Urinary NAG proved comparable to UAE when analyzed with respect to preexistence and development of severe macrovascular disease. It needs to be determined by further studies if urinary NAG will be of value to serve as an adjunct marker to UAE in type 2 diabetic patients.