The goal of this clinical trial is to investigate the sensitivity to glucagon in patients with type 2 diabetes mellitus (T2DM), with and without metabolic associated fatty liver disease (MASLD). The main questions it aims to answer are: 1. Is the sensitivity to glucagon with respect to hepatic FA oxidation and suppression of VLDL-TG secretion impaired in humans with T2DM and MASLD? 2. Is glucagon resistance and MASLD reflected in an aberrated lipidomic/metabolomic profile in blood and adipose tissue? Researchers will compare patients with T2DM with and without MASLD to see if the response to basal and high levels of glucagon differs between the groups. Participants will attend 2 short visits and 1 full-day visit, including: * Body scan (DXA) to check fat and bone composition * MRI to measure liver fat. * Blood tests. * Ultrasound to check liver stiffness and scarring. * Fat biopsies * 8-hour hormone (including glucagon) and tracer infusion * PET-CT scans