Exogenous and endogenous regulatory effects on lipid metabolism were studied by examining the fatty acid (FA) composition of food and the expression of the regulatory protein L-FABP in 43 individuals without diabetes (23 of them had increased blood glucose and cholesterol level and 20 formed a control group) and 76 patients with complicated diabetes mellitus (DM2). The main difference of lipid metabolism in patients with diabetes mellitus and non-diabetic patients was in the redistribution of FA content in erythrocyte membranes in the form of a 1.5-fold increase (P<0.05) in the content of saturated FA and decrease in unsaturated FA due to polyunsaturated FA (PUFA) and an increase the serum protein L-FABP 1.5 times (P>0.05). Eating food sources of various FAs according to the indicator of “rationality of food consumption”, which was obtained from food questionnaires analysis, did not differ in groups of people without diabetes and with diabetes. In the non-diabetic group with elevated blood glucose and cholesterol level, we revealed a decreased body mass index, a slight increase in PUFA in erythrocyte membranes and serum level L-FABP was 1.2 times lower than in relatively healthy subjects (P>0.05) and 2 times less than in patients with DM2 (P<0.05). It can be assumed, that under certain conditions, in the presence of metabolic shifts, it is the reduction of L-FABP expression with increased PUFA in cells that prevents the development of obesity and diabetes. Thus, the absence of a direct relationship between exogenous influences in the form of FA-source food products and the development of diabetes, the relationship between the expression of intracellular regulatory protein L-FABP and the redistribution of FA content in erythrocyte membranes allow us to consider endogenous cellular mechanisms as the basis of a deep violation of lipid homeostasis.