The premotor phase of Parkinson’s disease (PD) precedes the appearance of motor symptoms by years. Many non-motor diseases have been associated with an increased risk of developing PD, but results of these studies are conflicting. The aim of this study was to investigate the occurrence of certain internal diseases (metabolic, circulatory, gastrointestinal) based on diagnosis codes, before the diagnosis of PD. There were 5209 patients included in the study who received diagnosis of PD at least in 2 years and we analyzed data retrospectively between 2004 and 2016. Out of metabolic diseases dyslipidemia (41%) and diabetes mellitus (32%), out of circulatory diseases hypertension (89%) and ischemic heart disease (51%) and out of gastrointestinal diseases gastroesophageal reflux disease (51%) and gallstones (25%) were the first two most common disorders in the examined PD patients. This is the first study in Hungary which analyzed PD in a large database in the context of internal diseases, and raised the possibility of a link between dyslipidemias, diabetes mellitus, hypertension, ischemic heart disease, gastooesophagial reflux, gallstones and PD.