AIMS: (i) To examine the incidence of new onset treated diabetes in patients 
treated with different types of statins and (ii) the relationship between the 
duration and dose of statins and the subsequent development of new onset treated 
diabetes.
METHODS: A retrospective cohort study was performed using the Irish Health 
Services Executive Primary Care Reimbursement Services national pharmacy claims 
database. Individuals who received any medicines were identified from January 
2001 to January 2009 (n = 1 235 671). Patients newly treated with statins from 1 
January 2002 to 31 December 2007 were identified (n = 239 628). Cases were 
identified as individuals newly treated with antidiabetic medication (n = 
38 503). Adjusted hazards ratios (HR) with 95% confidence intervals (CI) were 
calculated to examine the association between statins (any vs. none) and time to 
new onset treated diabetes using Cox proportional hazard regression. The dose 
and duration response relationship between statins and new onset treated 
diabetes was examined using restricted spline functions to assess the linearity 
of the relationship.
RESULTS: Statin use was associated with an increased risk of new onset treated 
diabetes (HR = 1.18, 95% CI 1.15, 1.22). Increased risk of new onset treated 
diabetes was found with rosuvastatin (HR = 1.41, 95% CI 1.31, 1.52), 
atorvastatin (HR = 1.23, 95% CI 1.19, 1.27) and simvastatin (HR = 1.15, 95% CI 
1.05, 1.25). There were statistically significant overall dose and duration 
effects for all statins, excepting fluvastatin, which only demonstrated a 
duration effect.
CONCLUSION: An increased risk of new onset treated diabetes was found in those 
treated with statins showing significant duration and dose effect. Further study 
is required to confirm this association.