The effect of exercise on urinary excretion of different size proteins in patients with insulin-dependent diabetes mellitus.

To examine whether exercise-induced proteinuria in diabetes is dependent upon the size of the excreted protein, we measured urinary excretion of beta 2-microglobulin, kappa light chains, albumin and IgG before and after 20 min of moderate ergometer exercise in 34 patients with insulin dependent diabetes mellitus (IDDM) and in eight healthy control subjects. Seventeen patients with newly diagnosed IDDM and 17 patients (seven of which had elevated albumin excretion rate) with longstanding IDDM were studied. Exercise did not significantly influence protein excretion in control and newly diagnosed IDDM subjects. In contrast, exercise enhanced excretion of beta 2-microglobulin (p less than 0.05-0.01), kappa light chains (p less than 0.001), albumin (p less than 0.005-0.001) and IgG (p less than 0.01-0.001) in patients with long-standing IDDM independently of whether the patient had proteinuria in the resting state or not. In conclusion, proteinuria induced by moderate exercise is not observed in the early stages of IDDM, and is independent of the size of the excreted protein. Therefore, moderate exercise does not appear to influence the size selectivity of the glomerular capillary wall in patients with longstanding IDDM.