The measurement of urinary N-acetyl-β-D-glucosaminidase (NAG) activity has been thought to be useful for the early detection of diabetic nephropathy. On the other hand, urinary NAG has been reported to be positively correlated with blood sugar or glycosylated hemoglobin.
In order to assess the rapid change of urinary NAG activity in patients with glucose intolerance, its value was measured at vaious times during a 75-g oral glucose toleance test. The ratios of urinary NAG activity to urinary creatinine concentration, that is, NAG index, before and after glucose load, were compared. The mean value before glucose load in the 7 patients tested was 6.8±0.7 U/g·Cr (mean±SE), while the values at 2 and 3 hours after glucose load were 3.2±0.4 and 4.0±0.5 U/g·Cr, respectively. These two values were significantly lower than that before glucose load.
The estimation of urinary NAG activity for the early detection of diabetic nephropathy, should be done under some constant condition, for example, the measurement of the daily total amount or at the time or fasting.
