The protein intake-increasing allele C of FTO was significant associated with higher risk of T2DM (Beta ± SE = 0.104 ± 0.014, P = 4.40 × 10− 11), higher level of HOMA-IR (Beta ± SE = 0.016 ± 0.004, P = 9.55 × 10− 5), HOMA-B (Beta ± SE = 0.008 ± 0.003, P = 0.020), Hba1c (Beta ± SE = 0.008 ± 0.004, P = 0.028), whereas lower level of fasting insulin (Beta ± SE = − 0.015 ± 0.004, P = 7.48 × 10− 5). The gene discussed is INS; the disease is type 2 diabetes mellitus.