Free fatty acid and ketone body metabolism during exercise in diabetes

In diabetic patients the metabolic response to physical exercise is to a large extent determined by the degree of insulin deficiency at the onset of exercise. Thus, in well-controlled insulin-treated patients with mild hyperglycaemia and no or minimal ketonemia the utilization of FFA, blood glucose and glycogen by working muscle is similar to that of healthy subjects, and exercise is accompanied by a fall in blood glucose levels. In contrast, patients in poor metabolic control with marked hyperglycaemia, elevated FFA levels and hyperketonemia may respond to exercise with a further rise in FFA, ketone levels and blood glucose, reflecting augmented rates of adipose tissue lipolysis and hepatic ketogenesis. The accelerated rate of ketogenesis seen during exercise continues unabated in diabetics but not in healthy subjects during the post-exercise recovery period, thereby contributing to the development of post-exercise ketosis. These considerations underscore the importance of adequate insulin administration in connection with exercise in diabetic patients.