Diabetes mellitus acts as an independent risk factor for cardiovascular system. Middle-aged persons with diabetes mellitus present the same risk of morbidity and death due to ischemic heart disease (IHD) as persons without diabetes mellitus but with past history of myocardial infarction. Pathophysiology of the influence of diabetes mellitus on the function and structure of heart and vessels is mainly composed of the following disturbances:
- intracellural metabolic disturbances in cardiomyocites;
- microangiopathy of the heart;
- autonomic neuropathy;
- increased frequency and intensity of the coronary atherosclerosis;
- increased morbidity due to arterial hypertension.
The function and structure of the cardiomyocytes is primarly damaged by toxic effect of hyperglycemia and glycation of heart proteins as induced by the presence of diabetes mellitus. The increased concentration and metabolic turnover of fatty acids inhibits the uptake and oxidation of glucose and lactate by the heart. The proportion of energy for the heart action comes from the increased oxidation of fatty acids. The expression of GLUT-1 and GLUT-4 and, respectively, of cellular transportation of glucose is decreased. Angiopathic abnormalities in heart circulation limits adaptation to ischemia. The same results from autonomic neuropatyhy. Related to hyperglycemia oxidative stress impairs the function of the contractile proteins of the heart as well as of several infracellular enzymes. The proteins of the matrix of the heart are glycated, their proportion increases. It causes the diastolic cardiac insufficiency. Autonomic neuropathy of the heart also impairs metabolic and hemodynamic properties of the cardiomiocytes. Chronic hyperglycemia, in a very substantial way, is associated with atherogenic dislipidemia, endotheliopathy, hemostatic disorders, hyperuricemia, hyperhomocysteinemia etc. Coexistence of arterial hypertension in diabetes persons creates special, pathological demands for heart function. The natural history of the IHD in the diabetic persons is therefore accelerated with faster and more severe of manifestation of heart ischemia, myocardial infarction, heart failure and cardiac death. Quite often this history is complicated by silent myocardial infarction connected with higher mortality. The general prognosis of the IHD in diabetic persons is still 2–3 times worse in the comparison with general population. It creates special challenge for contemporary diabetology and cardiology.