PTPN22 and type 2 diabetes mellitus: Investigating the possible association of the PTPN22 C1858T polymorphism with more severe clinical manifestation at diagnosis, assessed by the presence or absence of ketoacidosis, patients with C1858T and T1858T genotypes were diagnosed with ketoacidosis more often (11.5% versus 7.7%) but not in a statistically significant higher rate.