Impact of inpatient management of hyperglycemia on peripheral T cell markers in patients with type 2 diabetes

Immune cell function is impaired in hyperglycemic patients with diabetes but thought to improve with normalization of blood glucose levels. In this study, we hypothesized that this improvement might involve changes in T cell function. We compared the peripheral T cell markers between the people with and without type 2 diabetes (T2D) admitted to our hospital for glycemic control, and then in patients with T2D before and after the improvement of hyperglycemia by inpatient treatment. Expression of programmed death 1 (PD-1) and T-cell immunoglobulin and mucin domain 3 (TIM-3), co-suppressive molecules, CD26 and CD28 on CD4-positive and/or CD8-positive T cells, the Th1/Th2 ratio, and the number of regulatory T cells (Tregs) were not significantly different between the people with and without T2D. Although an average of 10.6 days of inpatient treatment with improved hyperglycemia did not affect expression of PD-1 and TIM-3 in T cells, the Th1/Th2 ratio, or Tregs, it significantly reduced expression of CD26 and CD28 on CD4-positive T cells. CD26 and CD28 on CD4-positive T cells may be associated with the altered immune function after rapid improvement of hyperglycemia but that the other T-cell markers investigated here may not be.