Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic disorder that causes red blood cells become damaged or destroyed if stimulated by certain medications or foods, some viral infections, or acidosis caused by diabetes. The G6PD enzyme is an important part of the metabolism of glucose into glutathione, which protects the red blood cells from being destroyed by free radicals. G6PD deficiency occurs more often in men than in women as it is an X-linked recessive hereditary disease.