Augmentation of Insulin Activity: Physiological Implications of a Property of Human Serum Revealed by Dilution

Dilution of human serum does not lead to the expected reduction of its insulin-like activity (ILA) as measured by the epididymal fat pad. Dilution of a solution of Crystalline Insulin does, however, reduce activity arithmetically. Because the addition of Crystalline Insulin to diluted serum results in levels of ILA greater than expected (augmentation), the failure of ILA to fall arithmetically with dilution may reflect this augmentation effect on endogenous ILA.

The augmentation effect, as revealed by dilution and the addition of Crystalline Insulin, has been shown to increase in the serum of normal subjects after glucose loading, and to be deficient in fasting serum from the untreated diabetic patient.