Résumé : In 6 insulin deprived adolescent diabetics, the influence of muscular effort equal to 50% of the VO 2 max on the coefficient of glucose assimilation was evaluated. During an IVTT the coefficient of glucose assimilation at rest was (0.59) x 10 -2 ± 0.14 and it did not increase during physical activity. A minimal concentration of insulin is apparently indispensable to increase glucose utilization during muscular effort. At higher concentrations other factors probably intervene to enhance glucose assimilation.