This study was performed to test whether children born small for gestational age (SGA) with catch-up growth (CUG) could be associated with the early development of insulin resistance and the β-cell dysfunction and to explore the impacts of height CUG and weight CUG on the insulin resistance in a Chinese population. A total of 30 children born SGA with CUG, 37 non-CUG (NCUG), and 42 born appropriate for gestational age (AGA) with normal height were recruited. Their fasting serum insulin, fasting glucose, insulin-like growth factor-1 (IGF-1) concentrations, and the homeostasis assessment model for insulin resistance (HOMA-IR) and β-cell function (HOMA%) were evaluated. The values of HOMA-IR in CUG SGA were significantly higher than that in NCUG SGA (P = 0.002) and AGA children (P = 0.036), respectively. Correlation analysis revealed that the concentrations of fasting serum insulin were positively correlated with IGF-1 (r = 0.443, P = 0.001) and Δheight standard deviation score (SDS; r = 0.500, P = 0.002) in ≤ 6-year-old SGA children, but only with Δweight SDS (r = 0.496, P = 0.030) in >6-year-old children. In conclusion, SGA children with CUG in height and a higher body mass index are prone to the development of insulin resistance. Higher levels of insulin were closely correlated with the postnatal height CUG in young SGA children and with the weight CUG in old children.