Abstract
To clarify the significance of the parameters for detecting early diabetic nephropathy, urinary (u)-N-acetyl-β-D-glucosaminidase (NAG), u-total protein (TP), u-β2-microglobulin (β2MG) and serum (s)-NAG levels were determined in 61 type 1 diabetics who attended a summer camp and had no retinopathy or proteinuria, and in 19 age-, and sex-matched non-diabetic subjects.
1) U-NAG, u-TP and s-NAG levels were significantly higher in diabetics than in non-diabetic subjects, even though the duration of their diabeties was less than 2.5 years. No relation of any parameter with duration of diabetes was found. The incidence of patients having abnormal values was 42% for u-NAG, 27% for u-TP, 14% for u-β2MG, and 8% for s-NAG.
2) The relationship of each parameter level to five glycemic indices at different periods was investigated. U-NAG was most significantly correlated with the antecedent mean blood sugar level over the previous 7 days (r=0.47), whereas both u-TP and u-β2MG were most significantly correlated with urinary glucose level at the time of urine collection (r=0.77 for u-TP, r=0.37 for u-β2MG). No correlation was found between any parameter level and stable HbAi. Multiple variant analysis showed that 32% of u-NAG, 61% of u-TP, 19% of u-132MG and 20% of s-NAG were explained by the five glycemic indices. No relation was observed between any parameter and insulin dose, urinary C-peptide excretion rate, lipid level and so on.
These data suggest that functional alterations in renal tubulus and glomerulus may already occur in diabetics before the development of structural alterations in the kidney, and these alterations appear to be affected by the more recent glycemic levels in different manners.
