Dysfunction of autonomic nervous system is an important non motor feature of Parkinson' disease (PD). Lewy body formation is widely distributed in hypothalamus and in sympathetic and parasympathetic systems. Animal studies suggest a link between hypothalamus sensing of substrates and glucose metabolism. Thus, hypothalamus lesions could lead to change in glucose metabolism. Recently, we showed that fasting blood glucose level was significantly higher in PD patients than in control group suggesting that glucose tolerance may be impaired in PD. Some studies provided evidence for higher diabetes prevalence in PD patients whereas others showed no difference or a reduced risk of diabetes prevalence in PD patients compared to healthy subjects.