Association of extracellular heat shock protein 70 and insulin resistance in type 2 diabetes; independent of obesity and C-reactive protein

Despite few studies on intracellular heat shock protein70, the clinical association between insulin resistance and extracellular heat shock protein70 (eHSP70) is not well studied. In the current study, we examined the association between homeostatic model assessment-insulin resistance (HOMA-IR) and eHSP70 in patients with type 2 diabetes (T2DM) and healthy controls. A total of 145 patients with T2DM and 41 matched healthy controls were selected. Patients and controls were divided based on waist circumference (WC) to two groups, and eHSP70 was compared between them. The association between HOMA-IR and eHSP70 was examined using regression models adjusted for age, high-sensitive C-reactive protein (hs-CRP), and central obesity as confounding factors. While eHSP70 and hs-CRP were significantly correlated with HOMA-IR in patients with T2DM (p = 0.032, 0.025, respectively), there was no correlation between eHSP70 and HOMA-IR in the control group. Extracellular HSP70 and hs-CRP were not correlated in healthy controls. But a significant association appeared between eHSP70 and hs-CRP in patients with T2DM (p = 0.05). Both BMI and WC were not correlated with eHSP70 in both groups. Extracellular HSP70 was positively associated with HOMA-IR in patients with T2DM, independent from hs-CRP and obesity. We also showed eHSP70 levels remained unchanged through increase in BMI or WC in patients with T2D and in healthy controls. Our findings suggest that eHSP70 may contribute to the pathogenesis of T2DM by increasing insulin resistance.