to determine the number of sjTREC in type 2 diabetic patients and to analyze the potential factors affecting thymic output. The subjects of this study were 82 people: group I (n=68) - type 2 diabetic patients; group II (n=14) - healthy people. Measurements were taken: fasting glycemia, HbA1c, 1,5-AG (1,5-anhydro-D-glucitol), total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, C-peptide and interleukin-7. Quantification of sjTREC concentration in peripheral blood mononuclear cells was made by real time PCR. The concentration of sjTREC/10(5) PBMC was significantly lower in the group of diabetes as compared to control, while the level of IL-7 did not change between both groups. sjTREC levels are similar in obese group, but higher in patients with a short duration of diabetes, with better glycemic control (with low levels of fasting glycemia, HbA1c and higher 1,5-AG). Analysis of HbA1c covariance, indicator of chronic hyperglycemia, is a factor which primarily determines sjTREC differences between the groups, regardless of other factors. DM2 modifies sjTREC number in the peripheral blood. The level of sjTREC concentration is affected by DM2 duration, the degree of glycemic control. Thereby, chronic hyperglycemia leads primarily to metabolism deteriorations in the thymus, which results in decrease in its functional activity.