To determine tissue-specific glucose uptake during insulin stimulation from PET data, time-activity-curves of tissue activity and activity measured from plasma during the scanning are analysed graphically to define tracer's fractional uptake (Ki). To calculate glucose uptake rate (reported as µmol/kg/min), Ki is multiplied with plasma glucose level, divided with a constant that accounts for the differences in transport and dephosphorylation rates between D-glucose and FDG (lumped constant, LC) and divided with tissue specific gravity. Based on previous studies the LC is 1,2 for skeletal muscle; 1,0 for heart and liver; 1,14 for adipose tissue; 1,1 for intestines and 0,8 for brain. After the PET/CT an urine sample will be collected to quantify endogenous glucose production (EGP). This will be determined by subtracting urine loss and glucose infusion rate from rate of glucose disappearance.