In the T2DM and Diabetes subgroups (patients with diabetes of which type was not clear in the extracted study), insulin treatment significantly increased in-hospital admission for COVID-19 (T2DM, OR=1.31; 95% CI, 1.06-1.61; Diabetes, OR=2.86; 95% CI, 1.62-5.05), which was the opposite of the results in the T1DM subgroup (OR=0.14; 95% CI, 0.05-0.35). Here, INS is linked to type 2 diabetes mellitus.