Urinary Insulin Excretion Rate: An Index of Free Insulinaemia in Insulin‐dependent Diabetics

In 25 insulin-dependent diabetics, 14 managed by conventional insulin injection treatment (CIT) and 11 treated by continuous subcutaneous insulin infusion (CSII), there was a highly significant correlation between urinary insulin excretion rate (IER) per 1.73 m2 and mean serum free insulin concentration (r = 0.73, p less than 0.001), measured over a 24 h period. Urinary IER and mean daily serum free insulin levels were significantly higher in diabetics than in non-diabetics. CSII-treated patients had significantly lower mean 24 h plasma glucose levels than CIT-treated patients despite similar values of urinary IER and mean daily serum free insulin in the two groups. Urinary IER may be a useful indicator of average insulinaemia in large scale studies, avoiding the problems of multiple blood sampling and immunoassay in the presence of anti-insulin antibodies.