CA13 and type 2 diabetes mellitus: Interestingly, an increase in IBD/IBS was also observed for CA13 (carbonic anhydrase XIII), protein associated with colorectal cancer (CRC) [23], as well as SNAP23 (synaptosomal-associated protein 23) and NADK (NAD kinase) which are linked to insulin signalling and type 2 diabetes mellitus (T2DM) [24, 25].