Protective role of calcium ion against stress-induced osmotic fragility of red blood cells in patients with type 2 diabetes mellitus.

Type 2 diabetes mellitus can increase osmotic fragility of red blood cells. Osmotic fragility test is an index of the function of cytoskeletal proteins and of the calcium pump activity in RBC membrane. The aim of this study is to determine the effect of physiological calcium supplement on red blood cell osmotic fragility of patients with type 2 diabetes mellitus. Osmotic fragility of red cells was determined for 30 healthy subjects and 30 patients in a NaCl gradient medium. 5 mg/dl of calcium was added to media and the osmotic fragility were evaluated for RBCs of patients and healthy subjects. Comparison of patients and control group showed higher sensitivity of red cells of patients to osmotic fragility upon exposure to higher sodium chloride concentrations. Comparison of initial, fifty percent and total hemolysis showed significant difference on initial and fifty percent hemolysis between two groups (P < 0.001). In healthy subjects, Fifty percent hemolysis index showed a smaller change after addition of calcium, from 4.1 ± 0.22 to 3.9 ± 0.2 (P < 0.05). Fifty percent hemolysis index for patients significantly decreased from 4.45 ± 0.17 to 4 ± 0.17 after addition of calcium (P < 0.001). Osmotic fragility increases in patients with diabetes. The role of calcium in cell membrane integrity was more prominent in the patients with diabetes than the healthy subjects, emphasizing the role of calcium on the membrane stability. We showed for the first time that controlling calcium ion concentration in patients with diabetes could exert a protective and beneficial role against membrane-affecting conditions.