Twelve mature pedigree-clean cows, 11 mature cows and 1 bull known to be carriers of the " snorter " dwarf gene, and 12 " snorter " dwarfs were used in the investigation. The dwarf cattle proved to be much more sensitive to insulin than were the normal animals or the known carriers, as judged by changes in the blood glucose level after insulin treatment. It is suggested that the gene responsible for " snorter" dwarfism in some way upsets carbohydrate metabolism. Possibly the pituitary gland may not be functioning properly. Blood sugar determinations were of little value in distinguishing carriers of the dwarf gene from pedigree-clean animals because of the overlap between the 2 groups, although there was a significant difference between the 2 genotypes in mean glucose values.