Insulin resistance in type 2 diabetic patients reduces activation of PPAR, which may lead to accumulation of branched chain fatty acids as well as saturated fatty acids. Natural sources of these fatty acids are dairy products. The aim of our study was to verify whether the accumulation of branched chain fatty acids takes place in type 2 diabetes and in positive case to specify the corresponding lipid fraction. 23 anonymized plasma samples of type 2 diabetic patients, which were subsequently divided by glycosidic haemoglobin levels into groups of 11 compensated and 12 decompensated; and plasma of 10 healthy blood donors were processed. At first the samples were divided into particular lipid classes using the thin layer chromatography. Then we set the content of individual fatty acids in all lipid classes using the gas chromatography. Results were calculated with statistical application SigmaStat 3.5. The most abundant branched chain fatty acid is 14-methylhexadecanoic acid. Statistically significant increase of this acid was found both in compensated diabetics (p≤0.001) and in the decompensated ones (p≤0.001) in comparison with controls. The 14-methylhexadecanoic acid was found in diacylglycerol fraction as well as in the free fatty acid fraction in compensated (p=0.008) and decompensated (p=0.007) diabetics. Increase of the content of branched chain fatty acids in diabetic patients was proved. Accumulation of branched chain fatty acids in diabetics raises a question on the precise influence of these fatty acids on the human organism.