Sympathetic nervous system activation and lipid metabolism: the NEO study

The main objective of this thesis was to study the role of autonomic nervous system (ANS) function in the development of diabetes and cardiovascular disease using an epidemiological approach. Based on earlier studies it has remained unclear whether impaired ANS function is a risk factor for the development of diabetes and cardiovascular disease, or merely a consequence of pre-existing disease. The main conclusions of this thesis are that excess body fat, in particular visceral fat, is associated with activation of the sympathetic nervous system in individuals without diabetes and cardiovascular disease. Furthermore, this thesis showed that impaired ANS function is not a risk factor for the development of diabetes mellitus. The presented studies suggest that insulin resistance precedes the impairment of the ANS. The results from this thesis also show that impaired ANS function is a risk factor for the development of cardiovascular disease in populations without pre-existing cardiovascular disease. Furthermore, individuals with a higher heart rate have higher concentrations of cholesterol and triglycerides in the circulation and a higher intrahepatic triglyceride content, suggesting that an altered lipid metabolism may be a mechanism underlying the association between ANS function and cardiovascular disease