Impact of fasting and postprandial state on plasma carnitine concentrations during aerobic exercise in type 2 diabetes

Abstract

The effects of metabolic states of fasting and post-absorption on plasma concentrations of free carnitine (FC), acylcarnitine (AC) and total carnitine (TC) were compared during submaximal exercise in subjects with type 2 diabetes mellitus. Ten sedentary men (54+/-5 years) treated with oral hypoglycaemic agents were tested on two separate occasions: following an overnight fast and 2 h after a 395-kcal standardised breakfast. Exercise was performed at 60% of [Formula: see text]O(2peak) on a cycle ergometer for 60 min. Blood samples were drawn at rest for baseline values and following 60 min of exercise and 30 min of recovery. Our results show that: (1) baseline levels of TC, FC and AC were similar in fasted and postprandial groups, (2) TC and AC levels were increased during exercise in the fasted group only, (3) FC levels were decreased during exercise in both fasted and postprandial state and (4) the AC/FC ratio increased during exercise in the fasted group. Our results indicate that the metabolic state of the diabetic patient is associated with a different plasma carnitine status. These patterns may reflect differences in energy metabolism associated with fasting and postprandial hyperglycaemia.