The metabolic syndrome in twins: a consequence of low birth weight or of being a twin?

Background: to evaluate if being a twin is a condition at risk of developing metabolic abnormalities in the adult life 'per se' or as a consequence of the lower birth weight. Methods: 48 monozygotic twins and 50 non-twin controls, both with parental diabetes, were compared; the two groups were comparable for age, sex and body mass index. Results: twins showed higher values of blood pressure, triglycerides, insulin resistance, fasting insulin, insulin AUCs and higher prevalence of the metabolic syndrome, and, inversely, lower birth weight. After adjustment for birth weight, no significant association was evident with the twin status. Birth weight was inversely associated with the presence of the metabolic syndrome or of at least one or more of its components, while the positive association with the twin status was not significant. Conclusions: Our data suggest that low birth weight is more relevant than the twin status as a risk factor for the metabolic syndrome and its components.