Hepatic and intramyocellular glycogen stores in adults with type 1 diabetes and healthy controls

Methodological and physiological test-retest reliability of13C-MRS glycogen measurements in liver and in skeletal muscle of patients with type 1 diabetes and matched healthy controls

“…It is also noteworthy that no significant differences were found for hepatic or myocellular glycogen levels between patients and matched controls, which is in agreement with our earlier study (7).…”

“…Based on observation of the C1‐carbon of glycogen , natural abundance 13 C‐MR spectroscopy offers a very attractive, non‐invasive determination of glycogen levels in skeletal muscle (including studies assessing methodological and longitudinal intra‐subject variability) and liver (including studies assessing methodological and longitudinal intra‐subject variability). However, a major drawback of 13 C‐MRS is its inherently low sensitivity, resulting in rather long acquisition times, in particular if both hepatic and myocellular glycogen depots are to be evaluated . As long as 13 C‐MRS examinations in liver and muscle are performed once with a total measurement time of roughly an hour, this might be acceptable; however, since 13 C‐MRS examinations are usually longer than an hour and are often applied before and after interventions to observe the increase or decrease of glycogen levels, the required time multiplies and thus leads to an inacceptable duration of the whole examination (preparation period–pre‐intervention MRS–intervention–post‐intervention MRS).…”

“…Based on observation of the C1-carbon of glycogen (1,2), natural abundance 13 C-MR spectroscopy offers a very attractive, non-invasive determination of glycogen levels in skeletal muscle (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16) (including studies assessing methodological (2)(3)(4)(5)(6)13,14) and longitudinal (3,5) intra-subject variability) and liver C glycogen C-1 resonance in the phantom; A phantom-ref , fitted peak area of the acetone reference in a phantom measurement; A ref , fitted peak area of the acetone reference in a subject measurement; B 1 , field produced by the RF coil; BMI, body mass index; BMR, basal metabolic rate; c and c phantom , 13 C glycogen concentrations in vivo and in phantom, respectively; CHO, carbohydrate; CV, coefficient of variation; CW, continuous wave; f T1 , correction factor for the T 1 relaxation time; f NOE , correction factor for the NOE; HbA 1c , glycated hemoglobin (form of hemoglobin that is measured to identify the average plasma glucose concentration over prolonged periods of time); ISIS, image-selected in vivo spectroscopy; NOE, nuclear Overhauser enhancement; NOE Glyc , nuclear Overhauser enhancement of glycogen; NOE Crea , nuclear Overhauser enhancement of creatine; r, correlation coefficient; R1, time point of measurement, i.e. at time 0; R2, time point of measurement, i.e.…”

“…after a short break of a couple of minutes; SD, standard deviation; SNR, signal-to-noise ratio; T 1Glyc , longitudinal relaxation time of glycogen; T 1Crea , longitudinal relaxation time of creatine; T1DM, type 1 diabetes mellitus; T2DM, type 2 diabetes mellitus; T R , repetition time. (5,7,15,(17)(18)(19)(20)(21)(22)(23)(24) (including studies assessing methodological and longitudinal (5,19) intra-subject variability). However, a major drawback of 13 C-MRS is its inherently low sensitivity, resulting in rather long acquisition times, in particular if both hepatic and myocellular glycogen depots are to be evaluated (5,7).…”

Priming Effect of a Morning Meal on Hepatic Glucose Disposition Later in the Day

“…Individuals with diabetes have had lower postprandial levels of hepatic glycogen than normal controls in some (12,49,50), but not all (51–54), investigations. The degree of diabetes control seems to be a key determinant of postprandial hepatic glycogen content (54).…”