The protective effect of glucose, but not 3-O-methyl glucose, against alloxan-induced diabetes depends upon the route of hexose administration.

It is well established that pretreatment with glucose prevents the development of alloxan-induced diabetes in rodents. This was confirmed in the present study, and a protective effect against the development of hyperglycemia, after alloxan administration (75 mg/kg body weight), in male NMRI mice was observed when glucose was injected i.v. 10 or 20 min before alloxan injection. However, when glucose was administered i.p., a protective effect was only observed when glucose was given 20 min before alloxan, despite the fact that the serum glucose concentrations at the time of the alloxan injection were similar in the i.v.- and i.p.-injected animals. Administration of 3-O-methyl glucose by i.v. and i.p. routes protected against the effects of alloxan to the same extent. When alloxan was administered at a lower dose (65 mg/kg body weight) both i.v. and i.p. administration of glucose 10 min before alloxan, protected against the development of hyperglycemia. It is concluded that the route of administration of glucose, but not of 3-O-methyl glucose, affects its protective action against alloxan-induced diabetes. The present findings suggest that an important feature of the glucose mediated protection against alloxan-induced diabetes is the metabolism of glucose within the B-cells, rather than via extracellular effects on the B-cell plasma membrane.