In conclusion, healthy SGA children that experience a compensatory catch-up growth, leading to the restoration of their body composition at the age of four without relative fat mass excess, show mild disturbances of glucose tolerance associated to a lower glucose stimulated insulin secretion at 4-yrs of age suggesting impairment of β-cell function in line with the already described predisposition to type 2 diabetes later in life. This evidence concerns the gene INS and type 2 diabetes mellitus.