OBJECTIVE: To explore the contribution of genetic and environmental effects to insulin sensitivity.METHODS: The insulin sensitivity of 249 pairs of twins was estimated by use of logarithm transformed homeostasis model assessment (HOMA), of whom 169 pairs were monozygous and 80 pairs dizygous. To formulate a univariate genetic model for the variation of insulin sensitivity, the relative influences of gene and environment on the insulin sensitivity were divided into four contributing components as A (additive effects of alleles),D (dominance effects)  C (common environmental effects) and E (specific environmental effects). Heritability of insulin sensitivity was estimated by maximum  likelihood method, which included the influences of age and sex on model.RESULTS: The influence of age on insulin sensitivity was not significant  chi(2)=1.851  P=0.604  . The AE-model fitted the data best. The heritability of insulin sensitivity was 0.35 in males and 0.46 in females, respectively.CONCLUSION: 35% of the variance in insulin sensitivity was due to additive effects in males and 46% due to additive effects in females in this twin study.
Adult Age Factors