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Summary. Intraeellular glycogen deposits were consistently found in the retina, kidney and pancreatic islets of diabetie-ketonurie Chinese hamsters. Accumulation of glycogen in the outer nuclear layer of the retina was mostly associated with severity of the disease, but was not related to age or sex. The type of retinal cell involved in the accumulation of glycogen was not clearly established. Itowever, the position of the affected cell, side by side with retinal neurons, suggests that the glycogen deposits were within Miiller cells. These giant glias normally synthesize and store glycogen. All ketonuric Chinese hamsters examined showed some accumulation of glycogen in distal tubules of the kidney. This abnormal glycogen was not found in glueosurie non-ketonurie or in nondiabetic Chinese hamsters. Variable amounts of glycogen were found in fl cells of pancreatic islets of diabetic hamsters, as reported by others. I-iowever, accumulation of glycogen was also found in ~ and D islet cells from 2 middle aged Chinese hamsters with long term glueosuria and recent ketonuria. Abnormal glucose and glycogen metabolism seem to play an important role in the pathogenesis of diabetes in the Chinese hamster.

Two populations of Chinese hamsters have been produced. The nondiabetic population was from nondiabetic parents and the diabetic-producing population was from diabetic parents. Both populations had fixed reproducible genetic background since dams and sires were from inbred sublines. Sixty percent of males, but only 37~o of females, born to diabetic parents developed diabetes.-Life span for males was nondiabeties > mild diabetics > ketonurie diabetics. ]~esults for females were equivocal. Mortality of severe ketonuric diabetics appears to be related to urinary tract involvement. Survival appears to be rela~ed to abnormal metabolism, not genotype. On the basis of available data males appear more suitable for epidemiological studies on the incidence, onset, and severity of diabetes, on the evaluation of treatment of the disease, and on the longevity of diabetics.-Data on crossing diabetics from different sublines suggest that diabetic Chinese hamsters can have different genotypes.

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