Résumé : D-Glucose metabolism was examined in the lymphocytes of six subjects with the mitochondrial tRNALeu(UUR) gene mutation responsible for the maternally inherited diabetes and deafness MIDD syndrome and compared with control subjects. No significant difference in D-[1-14C]glucose, D-[2-14C]glucose, or D-[6-14C]glucose oxidation, as well as D-[5-3H]glucose utilization, was observed between the two groups of subjects. These negative findings stress the view that impaired D-glucose metabolism, such as presumably is occurring in the β-cells of patients with the MIDD syndrome, does not represent a universal feature found in all cell types of these patients. © 1995 Academic Press. All rights reserved.