Figure 1. Covariate Balance Plots.

A, Two overlaid balance plots (one for each outcome) for the type 2 diabetes cohort, each depicting both the unadjusted covariate balance and the balance achieved after adjustment using inverse propensity weighting (IPW). Negative values indicate that the metformin group has lower means and prevalence for the indicated covariates (in the case of sex, a higher percentage of males). The unadjusted balance markers indicate that the metformin users have spent less time in the hospital, have fewer or less severe comorbidities (lower Elixhauser Comorbidity Index in-hospital mortality scores), and appear healthier than insulin users across all Diabetes Complications Severity Index (DCSI) components. Across both outcomes, the IPW approach achieved satisfactory balance after adjusting for every observed covariate of interest. B, Two overlaid balance plots (one for each primary outcome) for the prediabetes cohort. Across both outcomes, the IPW approach achieved satisfactory balance after adjusting for every observed covariate of interest. The observed bias related to overall health and disease severity in the unadjusted analysis is mostly nullified in comparison with the type 2 diabetes cohort depicted in panel A.