INS and type 1 diabetes mellitus: The impact of fasting insulin differs across various models: in the T1D analysis, certain methods indicated a possible protective effect (MVMR-Median: OR = 0.79, 95% CI 0.65 to 0.97, p = 0.024; MVMR-Lasso: OR = 0.78, 95% CI 0.68 to 0.90, p < 0.001); conversely, the primary MVMR-IVW analysis in conjunction with T2D revealed no significant association (OR = 0.97, 95% CI 0.88 to 1.08, p = 0.586), while the MVMR-Lasso method suggested a moderate protective effect (OR = 0.91, 95% CI 0.833 to 0.99, p = 0.025) (Figure 4 and Figure 5).