We performed colocalization analysis and identified colocalizations for 15 proinsulin signals with signals for T2D (N = 12) or glycemic traits (N = 9): six previously known proinsulin signals near STARD10, MADD, TCF7L2, SGSM2, SLC30A8, and C2CD4A/B and nine additional proinsulin signals near SIX3, TLE1, RNF6, PAM, NKX6-3, FAM185A, BCL11A, GIPR, and FAM46C. We also identified colocalizations between an additional ten T2D or glycemic trait loci that were associated with proinsulin at a less stringent significance threshold (5 × 10−8 < p value < 1 × 10−4) (Table S8). This evidence concerns the gene MADD and type 2 diabetes mellitus.