As glucose is likely to be an important energy substrate for DKO mice even in the fasted state [3], our findings imply that marked hypoglycaemia due to fasting and FABP4/5 deficiency (Fig. 2a, groups 7 and 8) could cause detrimental effects on the exercise performance in fasted DKO mice. This evidence concerns the gene FABP4 and Hypoglycemia.