GSTM1 and type 2 diabetes mellitus: RCS analysis demonstrated a nonlinear, inverted L-shaped association between Hb and DR in men (P for nonlinearity = 0.041), whereas a linear inverse relationship was observed in women (P for nonlinearity = 0.977).<h4>Conclusions</h4>Hb levels are negatively associated with the presence of DR in Chinese patients with T2DM, suggesting that Hb may serve as a useful clinical indicator for DR risk stratification.