The purpose of this population-based, observational study is to evaluate the combined risk of serious ventricular arrhythmia (irregular heart rhythm) and sudden cardiac death in users of domperidone (a medication used to treat certain gastrointestinal disorders) compared with users of proton pump inhibitors (another group of medications used to reduce gastric or stomach acid production. The study will be conducted using patient information from Saskatchewan Health (SH) who had recorded dispensings of domperidone or a PPI from 1990 through 2005. The first objective of the study is to estimate the combined relative risk of the occurrence of a particular type of irregular heart rhythm known as serious ventricular arrhythmia (SVA) and sudden cardiac death SCD (defined as a natural death from an unexpected circulatory arrest) during current use of domperidone or current use of proton pump inhibitors (PPIs) as compared with nonuse in a diabetic population. The second objective is to estimate the combined relative risk of SVA and SCD during current use of domperidone or current use of PPIs as compared with nonuse in a non-diabetic population. Study drug dosing information not required for Observational Study