In the model matching for gender and age, the optimal cutoff value for serum IGF-I levels as an indicator of an auxiliary diagnosis of AIS was projected to be 135 ng/mL, which yielded a sensitivity of 77.8% and a specificity of 72.4%, with the area under the curve at 0.787 (95% CI: 0.694–0.848). This evidence concerns the gene IGF1 and androgen insensitivity syndrome.