Noninvasive Assessment of Exercise-Related Intramyocellular Acetylcarnitine in Euglycemia and Hyperglycemia in Patients With Type 1 Diabetes Using (1)H Magnetic Resonance Spectroscopy: A randomized single-blind crossover study

OBJECTIVE: Intramyocellular acetylcarnitine (IMAC) is involved in exercise-related fuel metabolism. It is not known whether levels of systemic glucose influence IMAC levels in type 1 diabetes. RESEARCH DESIGN AND METHODS: Seven male individuals with type 1 diabetes performed 120 min of aerobic exercise at 55–60% of Vo(2max) randomly on two occasions (glucose clamped to 5 or 11 mmol/l, identical insulinemia). Before and after exercise, IMAC was detected by (1)H magnetic resonance spectroscopy in musculus vastus intermedius. RESULTS: Postexercise levels of IMAC were significantly higher than pre-exercise values in euglycemia (4.30 ± 0.54 arbitrary units [a.u.], P < 0.001) and in hyperglycemia (2.44 ± 0.53 a.u., P = 0.01) and differed significantly according to glycemia (P < 0.01). The increase in exercise-related levels of IMAC was significantly higher in euglycemia (3.97 ± 0.45 a.u.) than in hyperglycemia (1.71 ± 0.50 a.u.; P < 0.01). CONCLUSIONS: The increase in IMAC associated with moderate aerobic exercise in individuals with type 1 diabetes was significantly higher in euglycemia than in hyperglycemia.