PDC and diabetes mellitus: Frequency of cases positive for CDKN2A promoter methylation in the PDC tissue was increased in long-DM at 30% (10/33 subjects) compared to 10% (6/59 subjects) in non-DM and 6% (1/17 subjects) in short-DM (p < 0.05 vs non-DM and short-DM) (Table 2).