It is known that small dense LDL particles are associated with an increased cardiovascular risk. LDL particles can be separated by gradient gel electrophoresis (GGE) according to their size. The risk to suffer from coronary heart disease is 3-7 fold elevated in subjects with small dense LDL particles compared to subjects with large LDL particles. This study aims at evaluating the predictive value of small dense LDL particles in patients with prediabetes and type 2 diabetes mellitus concerning future changes in intima media thickness, flow-mediated dilation and other risk factors of atherosclerosis (e.g. insulin resistance). 60 patients with prediabetes or type 2 diabetes will be recruited for the study. Assessment will include medical history (risk factors), physical examination (blood pressure, BMI, waist-to-hip ratio), collection of serum, oral glucose tolerance test, measurement of intima media thickness and endothelial dysfunction by ultrasound. All measurements will be repeated after 2 years. Data will be analysed to assess whether the amount of small dense LDL particles can predict further structural and functional changes of the cardiovascular system or changes in the severity of the disease (insulin resistance).