Therapeutic improvement of glucoregulation in newly diagnosed type 2 diabetes patients is associated with a reduction of IL-17 levels

We explored the effect of therapeutic glucoregulation on the blood levels of proinflammatory T helper (Th)17 cytokines interleukin (IL)-17 and IL-23, and Th1 cytokines interferon (IFN)-γ and IL-12 in newly diagnosed type 2 diabetes patients. The investigated group consisted of 23 subjects (17 men and 6 women, age 26–64). The cytokine serum levels, glycated hemoglobin (HbA1c) as a marker of glucoregulation, homeostasis model assessment index as a measure of insulin resistance (HOMA-IR), and body mass index (BMI) were determined before and after 12 weeks of therapy consisting of standard lifestyle modification and metformin (1000 mg b.i.d.). The levels of Th17 and Th1 cytokines before treatment did not correlate with age, BMI or HOMA-IR. The patients with poor glucoregulation (HbA1c > 7%, n = 12), compared to those with good glucoregulation (HbA1c ≤ 7%, n = 11), had higher serum levels of Th17 and Th1 cytokines, but only the differences in IL-17 (median 21.2 pg/ml vs. 4.8 pg/ml) and IFN-γ 5 (0.6 pg/ml vs. 27.7 pg/ml) reached statistical significance (p = 0.003 and p = 0.012, respectively). The reduction of HbA1c values (from 8.6 to 5.9%, p = 0.000) observed upon treatment in patients with poor glucoregulation was associated with a significant decrease in the concentration of IL-17 (from 21.2 to 12.9 pg/ml, p = 0.020), but not IFN-γ (50.6 vs. 52.3, p = 0.349). These data indicate that therapeutic improvement of glucoregulation might contribute to a reduction of IL-17 levels in newly diagnosed type 2 diabetes patients.