Methodological and physiological test–retest reliability of 13C‐MRS glycogen measurements in liver and in skeletal muscle of patients with type 1 diabetes and matched healthy controls

Glycogen is a major substrate in energy metabolism and particularly important to prevent hypoglycemia in pathologies of glucose homeostasis such as type 1 diabetes mellitus (T1DM). 13C‐MRS is increasingly used to determine glycogen in skeletal muscle and liver non‐invasively; however, the low signal‐to‐noise ratio leads to long acquisition times, particularly when glycogen levels are determined before and after interventions. In order to ease the requirements for the subjects and to avoid systematic effects of the lengthy examination, we evaluated if a standardized preparation period would allow us to shift the baseline (pre‐intervention) experiments to a preceding day.