Inner ear damage secondary to diabetes mellitus. I. Changes in adolescent SHR/N-cp rats.

The association between diabetes mellitus and hearing impairment has been debated in many previous studies. The spontaneous hypertensive/NIH-corpulent (SHR/N-cp) rat has been shown to be a unique genetic model for non-insulin-dependent diabetes mellitus. Seventeen diabetic and 17 control young male rats were divided into groups according to diet and phenotype. The rats were fed either 54% of sucrose or 54% starch diets for 3.5 months and killed at 5 months. The cochleas were fixed, decalcified, dissected, and stained for hair cell counting. A significant loss of outer hair cells was noted in the diabetic obese (SHR/N-cp) animals when compared with the control obese (LA/N-cp) animals in every group. Although no significant difference was noted between the diabetic obese (SHR/N-cp) animals receiving the starch and sugar diets, the diabetic obese (SHR/N-cp) animals were more severely affected than the nondiabetic lean (SHR/N-cp) rats.