Urinary transferrin excretion in type 1 (insulin-dependent) diabetes mellitus

Urinary excretion of transferrin and albumin was studied by radioimmunoassay in 47 adult patients with Type 1 diabetes and 28 control subjects. Median (range) urinary transferrin excretion rate was significantly elevated in the diabetic group 0.58 (0.02–2663.3) μg min−1 compared with the control group 0.04 (0.01-0.28) μg min−1, p<0.001. Urinary transferrin:creatinine ratios (x 102) were different in diabetic 47 (0.6–958.0) μg mmol−1 and control groups 0.7 (0.06-2.3) μg mmol−1, p<0.001. There were correlations between urinary transferrin and albumin excretion rates in diabetic (r=0.78, p<0.001) and control groups (r=0.81, p<0.05). Forty (85%) diabetic patients had elevated transferrin excretion rates, 18 (38.3%) had elevated albumin excretion rates. All diabetic patients with elevated albumin excretion rates had elevated transferrin excretion rates. Twenty-one (77.8%) of the patients with normal albumin excretion rates had elevated transferrin excretion rates. Urinary excretion of N-acetyl-β-d-glucosaminidase was greater in diabetic patients than control subjects (142 vs 58 μmol h−1 I−1, p<0.001). There were correlations between transferrin and N-acetyl-β-d-glucosaminidase excretion (r=0.67, p<0.01) and albumin and N-acetyl-β-d-glucosaminidase excretion (r=0.63, p<0.01) in the diabetic group. Elevated urinary transferrin excretion rate may be a marker for renal dysfunction in diabetes mellitus.