Characterization of diabetes in the Chinese hamster.

Abstract

Diabetes in Chinese hamster was initially detected by qualitative tests for urine glucose. The disease was characterized by quantitating urine glucose, glucose tolerance tests and measurement of fasting and nonfasting blood sugar, blood ketones, plasma free fatty acids (FFA), plasma insulin, pancreatic insulin and fasting levels of liver glycogen. In addition, basal levels of glucose utilization by diaphragms and epididymal adipose tissue and the response of these tissues to insulin was measured. Those animals requiring insulin received their last injection 24 hours prior to study. Glucosuria varied from 51 to 1600 mg/24 hours. Diabetics had significantly decreased tolerance to a 250 mg/kg glucose load. The response varied considerably in diabetics but was uniform in the nondiabetics. Diabetics had mean fasting liver glycogen levels of 3.1±1.0 compared with 0.4± 0.7 percent of fresh liver weight for nondiabetics. Severely ketotic, diabetic Chinese hamsters had significantly elevated FFA and ketone levels and significantly lower plasma and pancreatic insulin levels but mild diabetics did not differ from controls with respect to these parameters. All Chinese hamsters had high plasma FFA levels (nondiabetics 1800μE/l, severe diabetics 2800μE/l. Fasting and nonfasting FFA levels did not differ in mild diabetic and nondiabetic animals. Muscle and adipose tissues from diabetic hamsters had basal rates similar to nondiabetics and had similar responses to insulin. Hamsters maintained on insulin had greatly elevated immunoreactive insulin levels in their plasma, which persisted for 26 days. — The data suggest that severely diabetic hamsters may have a decreased ability of the pancreas to secrete insulin in response to a glucose stimulus. The observations that plasma insulin levels are normal in mild diabetics but that these animals have glucosuria, hyperglycemia and abnormal glucose tolerance suggest that mild diabetes in the Chinese hamster may involve interference with insulin action and/or increased hepatic glucose output.