Imaging myocellular lipid droplet dynamics in relation to insulin sensitivity: Analysis in human intervention studies

Fat (or lipids) are not only stored in the adipose tissue (body fat), but also in the muscle in the form of small lipid droplets. People who have type 2 diabetes have high levels of muscle fat, which is often associated with the development of insulin resistance (less responsiveness to the hormone insulin, which can ultimately lead to type 2 diabetes). However, endurance trained athletes also store high amount of fat, while remaining highly insulin sensitive. This indicates that the relation between muscle fat and the development of insulin resistance is more complex. Indeed, lipid storage is not an inert source of fuel, but highly dynamic and dependent on many factors such as internal storage, substrate availability and energy demand. Preservation of the dynamic nature of LDs is essential to maintain metabolic health and disturbances can affect insulin sensitivity (and possible lead to type 2 diabetes). The main aim of this thesis was to study LD dynamics in the muscle in relation to insulin sensitivity. Microscopy techniques have been used to study many features of LD dynamics in human intervention that affected either lipid metabolism or insulin sensitivity.