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The Relationship of Vitamin B12to Carbohydrate Metabolism and Diabetes Mellitus

1957; Elsevier BV; Volume: 5; Issue: 4 Linguagem: Inglês

10.1093/ajcn/5.4.431

1938-3207

Bacon F. Chow, Howard H. Stone,

Growth Hormone and Insulin-like Growth Factors

This report consists of a brief summary of experimental studies which emphasize (a) the dominant role played by vitamin B12in the utilization of carbohydrates, (b) interrelationships between vitamin B12absorption and endocrine function, and (c) some relationships of vitamin B12to diabetes mellitus. (1) Weanling rats fed a diet, rich in carbohydrate and low in fat require more vitamin B12for growth. (2) The fat content of the carcass of vitamin B12-deficient rats is abnormally low but can be elevated by injection of this vitamin. (3) The administration of glucose to rats results in a decrease in the vitamin B12levels of plasma or liver. (4) Deficiency of vitamin B12causes hyperglycemia correctable with vitamin B12.In vitroexperiments indicate that the red cells of vitamin B12-deficient animals are low in glutathione content as well as enzyme activity essential for the degradation of glucose. Other enzyme systems involved in carbohydrate metabolism such as coenzyme A in liver or DPN in liver are also deranged due to this deficiency. (5) The effect of cortisone and thyroid on absorption of orally administered vitamin B12and retention of injected vitamin B12was re-emphasized. It was found that corticotropin (ACTH) or cortisone causes hyperglycemia, destruction of vitamin B12-binding substances in muscles as well as an elevation of the vitamin B12serum level. Thyroidectomy decreases absorption of vitamin B12. (6) Some evidence of adrenal hyperactivity in diabetic patients with diabetic retinopathy, (as gathered by other investigators), has been reviewed. We caution against a premature interpretation that adrenal hyperactivity is causally or pathogenetically related to diabetic retinopathy; it may turn out to be a mere associated phenomenon. (7) Diabetic patients without retinopathy excrete in their urines a significantly smaller amount of an orally administered radioactive vitamin B12-test dose than do non-diabetic subjects or diabetic patients with retinopathy. Fecal excretion tests confirm the above findings.