Strikingly, the median proinsulin:C-peptide ratio was significantly increased in those diagnosed at <7 years compared with individuals diagnosed at ≥13 years (Fig. 6) (0.18, IQR 0.10–0.31 vs 0.01, IQR 0.01–0.10; p < 0.0001) and control individuals without diabetes (0.003, IQR 0.002–0.005; p < 0.0001). Here, INS is linked to diabetes mellitus.