INS and metabolic syndrome: Furthermore, low levels of serum IGF-I were significantly related with the metabolic syndrome according to the World Health Organization.[19] However, our findings are consistent with the animal studies demonstrating low insulin sensitivity in mice with liver specific deletion of the IGF-I gene that is reversed by treatment with recombinant human IGF-I.[3, 4] Raised blood pressure and slightly enhanced plasma insulin concentrations have been reported in mice with a mutant IGF-I allele causing a marked decrease in circulating IGF-I levels.[20]