Micro assays for glucose and insulin

Micro assay techniques for the estimation of blood glucose and plasma insulin in rats and humans are fully described. Only 50 p.L of rat blood is needed (5 μL of hole blood for the glucose assay and 10- 15 μL of plasma for the insulin assay which can be done in duplicate or triplicate). This method has allowed the measurement of glucose and insulin in small animals without the need to sacrifice them. Both assays are sensitive and reproducible. The sensitivity of the rat insulin assay (0,5 ng/ml) was adequate for the measurement of rat plasma insulin, and the interassay coefficient of variation of 10,5% compared favourably with 8,60/0 found in the conventional assay. In order to increase the sensitivity of the assay for human plasma insulin, the sample volume is increased to 10 μL and more dilute first antibody is used. Values of plasma insulin from 0,15 to 2 ng/ml (4 - 50 μU/ml) can be determined using heparinised capillary blood from a heel tab, and thus avoiding repeated venepunctures in infants and neonates.S. Afr. Med. J., 48, 365 (1974)