altered metabolic incorporation of fucose and leucine into pns myelin of 25weekold diabetic c57blks dbdb mice effects of untreated diabetes on nerve metabolism sciatic nerves of 25weekold genetically diabetic c57blks dbdb mice and their littermate controls were removed and their metabolic incorporation of 3hfucose and 14cleucine into myelin was studied in vitro untreated diabetic animals showed significant increases p less than 005 in the fucoseleucine incorporation into myelin when compared to values found for their littermates these results correlated well with previous experiments performed on alloxan or streptozotocindiabetic rats and thus show the in vitro incubation procedure to be a good indicator of altered metabolic conditions in peripheral nerves due to diabetes mellitus the resulting ratio increases seen in diabetic animals is at variance with the decrease in ratios found in animals undergoing typical wallerian degeneration these results suggest that different metabolic processes operate in untreated diabetics than in normals or in those undergoing other degenerative nerve processes