Significance of genetic factors for the plasma insulin response to glucose in healthy subjects.

The intravenous glucose tolerance and plasma insulin response to glucose infusion were analysed in a twin and family material, comprising 279 healthy subjects. The relation between the blood glucose and plasma insulin values was studied by an analysis of the principal eigenvalues. The variables obtained were corrected for sex, age and weight, and standardized with regard to mean and variance. The results showed that at least four of the variables have appreciable familial correlations, corresponding to a heritability (h2) varying between 0.38 and 0.72. These correlations could not be accounted for by common environment alone. Thus, the beta cell function in normal man, as measured by a glucose challenge test, appears to be genetically regulated.