Urinary sulfosalicylic acid-soluble mucoprotein (U-SSMP) concentrations were measured in 67 diabetic patients with or without clinical diabetic nephropathy and their correlation with urinary N-acetyl-beta-D-glucosaminidase (NAG) activities, serum creatinine and HbA1c levels, was studied.
The diabetic group showed a significant increase in U-SSMP levels compared to non-diabetic controls (17.27 ± 1.34 vs 6.51 ± 0.62 mg/dl, p< 0.001) The U-SSMP concentrations in diabetics without proteinuria, with intermittent proteinuria and with persistent proteinuria were 15.24 ± 1.38 (n=48), 24.20 ± 5.85 (n=10) and 20.40 ± 3.08 mg/dl (n=9), respectively. All these values were significantly higher than those in non-diabetics. In addition, diabetics with intermittent proteinuria showed significantly higher levels of U-SSMP than those without proteinuria (p< 0.05).
A significantly positive correlation was observed between U-SSMP concentrations and urinary NAG activities (r=0.80, n=67, p< 0.001). A positive correlaion was also found between U-SSMP concentrations and HbA1c levels.
U-SSMP concentrations were abnormally high in 20 %(10/48) of the diabetics without proteinuria whose urinary NAG activities were normal. In contrast, only 6 %(3/48) of the diabetics without proteinuria demonstrated elevated urinary NAG activities despite normal U-SSMP levels.
These results suggest that the increased U-SSMP levels seen in diabetics might be associated with early diabetic renal involvement, although many additional studies will be needed to confirm this.
