title: Genetic and environmental effects on fasting and postchallenge plasma glucose and serum insulin values in Finnish twins.
abstract: The aim of this study was to evaluate genetic and environmental effects on plasma glucose, insulin secretion, and resistance in Finnish twins. Altogether 151 randomly selected twin pairs were examined by the oral glucose tolerance test; 66 twin pairs were monozygotic and 85 like-sexed dizygotic. We estimated the intraclass correlation coefficients and variance components of genetic and environmental effects on waist circumference, plasma glucose, and serum insulin. For fasting insulin, the proportion of total variation accounted for by additive genetic effects (A) and nonshared environmental effects (E) were 43 and 57%, respectively. As to postchallenge insulin and waist circumference, A effects were stronger in female twins (51 and 70%, respectively) than male twins in whom no significant evidence for genetic variance was found. Of the variation in fasting glucose, A and E effects accounted for 45 and 55%, respectively. Of the variation in postchallenge glucose, E effects had a greater role (65%), compared with A effects (35%); A effects on pre- and postchallenge insulin levels were highly correlated (genetic correlation coefficient = 0.81). In conclusion, additive genetic effects are important for the insulin secretion, whereas nonshared environmental effects contribute strongly to peripheral insulin resistance.
authors.affiliation: Diabetes and Genetic Epidemiology Unit, National Public Health Institute, Helsinki, Finland.
authors.forename: Shuichi
authors.initials: S
authors.lastname: Katoh
authors.forename: Mikko
authors.initials: M
authors.lastname: Lehtovirta
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.forename: Valma
authors.initials: V
authors.lastname: Harjutsalo
authors.forename: Markku
authors.initials: M
authors.lastname: Koskenvuo
authors.forename: Johan
authors.initials: J
authors.lastname: Eriksson
authors.forename: Naoko
authors.initials: N
authors.lastname: Tajima
authors.forename: Jaakko
authors.initials: J
authors.lastname: Tuomilehto
mesh_terms: D001786:Blood Glucose / Q000032:analysis*; D004777:Environment; D005215:Fasting / Q000097:blood*; D005260:Female; D006801:Humans; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012737:Sex Factors; D014427:Twins
chemical_list: D001786:Blood Glucose; D007328:Insulin