A new diabetic mouse model derived from the ddY strain.

Selective breeding was used to isolate hyperglycemic (ddY-H) or normoglycemic (ddY-L) mice that had been induced by fasting and refeeding. Serum glucose levels 12 h after 48 h-fasting were high in male ddY-H mice, but relatively low in male ddY-L mice compared with control ddY mice. Glucose tolerance was impaired in ddY-H mice maintained with standard chow pellets ad libitum at 12 weeks of age, and serum glucose and insulin levels were significantly increased after overnight fasting at 15 weeks of age. ddY-L mice indices did not differ from ddY mice indices, suggesting that insulin resistance is spontaneously induced in ddY-H mice. Increases in urinary excretion and urinary sugar accompanied by increased body mass were observed in all ddY-H mice, but not in ddY or ddY-L mice, at 27 weeks of age, indicating the induction of diabetic symptoms. Cross-mating between ddY-H and ddY-L mice was used to certify the genetic involvement in impaired glucose tolerance. This was not induced in mice born from male ddY-H and female ddY-L mice, or from female ddY-H and male ddY-L mice. In conclusion, ddY-H mice are a useful diabetic mouse model that show spontaneously induced insulin resistance followed by diabetic symptoms that are maintained by standard chow pellets. Their characteristics are recessively inherited, and ddY-L mice are an appropriate choice as control mice.