Delayed Effects of Proton Irradiation in Macaca mulatta. III. Glucose Intolerance.

Abstract : A group of rhesus monkeys is being studied in a lifetime survey of the delayed effects of proton irradiation. The animals were exposed during the period 1964 - 1969 to single total-body doses of protons covering the spectrum of energies and total doses that might be expected to occur in space during a major solar flare event. This report describes the results of intravenous glucose tolerance test and the insulin response to glucose challenge in 106 irradiated animals, their control group of 42, and 10 younger control animals. The results indicate that the clearance rate of blood glucose is influenced by the age of the animal and by the type and energy of the radiation. Animals receiving greater than 360 rads of proton irradiation of energies above 138 MeV had significantly slower glucose clearance than nonirradiated controls. Seventeen-twenty-year-old controls were less glucose tolerant than 9-11-year-old controls. Animals with normal glucose tolerance showed considerable individual variation in insulin response, while in animals with marked glucose intolerance (clearance rate 1.0 %/min), low insulin response was a consistent finding.