Obesity and diabetes have reached epidemic proportions and have emerged as massive public health problems globally. The etiology of both obesity and diabetes are related, multifactorial, highly complex, and involves interplay of genetic, environmental, socio-economic and physiological factors, which calls for a more extensive research in understanding the risk factors and biological pathways. Hence, this dissertation contributed in part to understanding the role of iron markers in the development of type 2 diabetes mellitus and the role of intrauterine hyperglycemia in influencing the risk of offspring obesity along with investigating potential pathways. In the first part of my dissertation, the associations of iron markers (ferritin and transferrin) with type 2 diabetes mellitus and metabolic syndrome were investigated using the population-based Study of Health in Pomerania. The present analyses were based on 3,232 participants aged 20-81 years with a follow-up time of nearly 11 years. The results suggest that serum ferritin concentrations were associated with a higher prevalence of type 2 diabetes mellitus and metabolic syndrome in the total population as well as in men. However, the effects of serum ferritin on incident type 2 diabetes mellitus were observed only in women, while the effects on incident metabolic syndrome were seen in the total population. Serum ferritin is also known to reflect systemic inflammation or hepatic dysfunction in addition to increased iron ...