The diabetic heart utilizes ketone bodies as an energy source

BACKGROUND: Diabetic heart is characterized by failure of insulin to increase glucose uptake and increasingly relies on free fatty acids (FFAs) as a source of fuel in animal models. However, it is not well known how cardiac energy metabolism is altered in diabetic hearts in humans. We examined cardiac fuel metabolism in the diabetics as compared to non-diabetics who underwent cardiac catheterization for heart diseases. MATERIAL AND METHODS: The study subjects comprised 81 patients (male 55, female 26, average age 63.0±10.0years) who underwent the cardiac catheterization for heart diseases. Thirty-six patients were diagnosed as diabetics (diabetic group) and 45 as non-diabetics (non-diabetic group). Blood samplings were done in both the aortic root (Ao) and coronary sinus (CS) simultaneously and the plasma levels of FFAs, glucose, lactate, pyruvate, total ketone bodies and β-hydroxybutyrate were measured and compared between the two groups. RESULTS: The myocardial uptake of glucose, lactate and pyruvate were decreased, whereas those of total ketone bodies, β-hydroxybutyrate and acetoacetate were increased in the diabetics as compared to the non-diabetics. However, the myocardial uptakes of FFAs were not significantly increased in the diabetics as compared to the non-diabetics. CONCLUSIONS: Cardiac uptakes of carbohydrate (glucose, lactate and pyruvate) were decreased, whereas those of total ketone bodies and β-hydroxybutyrate were increased in the diabetics as compared to the non-diabetics in humans. Ketone bodies therefore are utilized as an energy source partially replacing glucose in the human diabetic heart.