Impaired Glucose Tolerance in the Squirrel Monkey (Saimiri sciureus) ∗

Abstract

Abnormalities of carbohydrate metabolism in a number of animal species have been reported (1,2). The prevalence of a naturally occurring glucose tolerance “impairment” in the squirrel monkey (Saimiri sciureus) is reported here.

Method. The 200 monkeys used in this study were supplied by the Tarpon Zoo, Tarpon Springs, Fla., from their supply source at Leticia, Colombia, So. America. In this group, 65 were juveniles and 135 were adults. The monkeys were held at the Tarpon Zoo for periods varying from 3 weeks to 4 months during which time they were fed Pablum† mixed with diluted condensed milk, Purina Monkey Chow, fresh fruit, and one-half egg per monkey per week. This group included only monkeys free of apparent disease.

Blood samples were obtained after an 18-hour fast and immediately afterwards, glucose (4 g kg of body weight) (3) was administered to the monkeys through a stomach tube.‡ Blood samples were obtained at 1 hour and at 4 hours following administration of glucose. Blood glucose values were determined using an Auto-Analyzer§ procedure.

One of the difficulties in the statistical evaluation of glucose tolerance data has been the inability to express the glucose tolerance curve with a single numerical description. However, to examine the distribution of these data it was necessary that a single value be used that was descriptive of each animal's glucose tolerance curve. In order to arrive at such a single value the difference between the 1-hour blood glucose level and the fasting blood glucose level was added to the difference multiplied by 3 between the 4-hour blood glucose level and the fasting blood glucose level and this sum was divided by 4 to give a mean difference value. The glucose tolerance data were weighted in this way because the 4-hour sample most nearly reflected the animals' tolerance for carbohydrate.