The decrease of the number of CD8+ T and CD19+ B cells expressing the TLR9 receptor in patients’ cases at an early stage of the disease compared to patients treated chronically and demonstrated significant relationships with HbA1c and the concentration of fructosamine confirms that changes in the expression of this receptor may be involved in the regulation of glucose metabolism of patients with type 1 diabetes. The gene discussed is CD19; the disease is type 1 diabetes mellitus.