Type 2 diabetes mellitus and survival in pancreatic adenocarcinoma

BACKGROUND: Recent evidence has identified pre-existing type 2 diabetes mellitus (T2DM) as a risk factor for the development of PAC, but relatively little is known about its effects on survival. Our aim was to determine the effect of varying durations of pre-existing T2DM on survival in patients with PAC. METHODS: We conducted a retrospective cohort study using The Health Improvement Network (THIN), a primary care electronic medical record database from the UK (2003-2010). The study cohort included all subjects with a diagnostic code for PAC. Subjects with a diagnostic code for T2DM before their PAC diagnosis were classified as exposed; otherwise, subjects were classified as unexposed. The primary outcome was overall survival. The analysis was performed using univariate and multivariable Cox proportional-hazards models. Additional analysis was performed to assess the effect of increasing duration of pre-existing T2DM [i.e., <90 days, 90 days to <1 year, 1 to <3 years, 3 to 5 years, >5 years] on survival. RESULTS: The study included 3,147 patients with PAC, with 745 patients having pre-existing T2DM and 2,402 patients without pre-existing T2DM. In the primary multivariate analysis, there was no difference in survival between those exposed and those unexposed to pre-existing T2DM (HR 1.02 [0.93, 1.12], p = 0.620). In the secondary analysis, only those patients with T2DM > 5 years duration had a significantly increased mortality (HR 1.16 [1.00, 1.33], p < 0.05). CONCLUSIONS: Long-term pre-existing T2DM is associated with increased mortality in patients diagnosed with PAC.