In the MVMR analysis controlling for glycated hemoglobin, robust evidence was demonstrated for a direct causal effect of ALT (IVW OR = 1.672, 95% CI = 1.434–1.910, p < 0.001, per SD increase of ALT) and AST (IVW OR = 1.592, 95% CI = 1.247–1.936, p = 0.008, per SD increase of AST) on the risk of T2DM with DR (Fig 3A and 3B). Here, GPT is linked to type 2 diabetes mellitus.