ARAP1 and type 2 diabetes mellitus: By contrast, the T2D-risk alleles at a locus adjacent to ARAP1 (MIM: 606646) (formerly called CENTD2) and STARD10 on chromosome 11q1320, 21 are robustly associated with a marked reduction in proinsulin:insulin ratios.19, 22 This unusual pattern implies preserved or improved proinsulin processing despite increased T2D risk.