Meta-regression indicated a negative association between age of onset and body fat % (unstandardized β = −2.3, 95%CI −3.5– −1.0; p < 0.001, n = 12) (Figure 3, Supplementary Table 6), and a positive association between insulin dosage (U/kg/day) and body fat % mean difference between children with T1D and TDC (unstandardized β = 18.1, 95%CI 3.5–32.6; p = 0.015, n = 13) (Figure 4, Supplementary Table 6). The gene discussed is INS; the disease is type 1 diabetes mellitus.