One of the most widely-used models to study IGF-1 deficiency in aging is an adult-onset circulating IGF-1 knockdown model in which liver-specific IGF-1 knockdown is induced post-development (~3-6 months of age) via injection of AAV-TBG-Cre. This evidence concerns the gene IGF1 and hyperinsulinemic hypoglycemia, familial, 4.