Red cell membrane (Na+ +K+)-ATPase in diabetes mellitus.

The red cell membrane (Na+ +K+)-ATPase activity is significantly elevated in diabetes mellitus. The osmotic fragility of diabetic red cells is also increased. In vivo insulin treatment restores the enzyme activity and the osmotic fragility to the normal level. In vitro insulin treatment of diabetic red cells was found to inhibit the further increase in its activity, but it failed to restore the activity to the normal level as in vivo. In diabetes increased Km of (Na+ +K+) ATPase for ATP was observed but Vmax remained the same. Arrhenius plot of this enzyme was also altered in diabetes.