Relationship between thioredoxin-interacting protein (TXNIP) and islet β-cell dysfunction in patients with impaired glucose tolerance and hypertriglyceridemia.

AIMS To study the relationship between thioredoxin-interacting protein (TXNIP) and pancreatic β-cell function in patients with impaired glucose regulation and patients with both impaired glucose regulation and hypertriglyceridemia. METHODS We analyzed a population of 90 patients with impaired glucose regulation (IGR), 87 patients with IGR and hypertriglyceridemia, and 90 subjects with normal glucose tolerance (NGT). The levels of plasma TXNIP, a regulator of cellular oxidative stress, were measured. The homeostasis model assessment for insulin resistance (HOMA-IR) was used to evaluate insulin resistance in all subjects. In addition, two factors (HOMA for β-cell function [HOMA-β]) and first-phase insulin response [FPIR]) were used to evaluate pancreatic β-cell function. The correlations between the plasma levels of TXNIP, insulin resistance, and islet β-cell dysfunction were analyzed using Pearson's correlation analysis. RESULTS Compared with NGT, patients with IGR had significantly lower HOMA-β and FPIR, and higher plasma levels of TXNIP. Compared with the IGR group, patients with both IGR and hypertriglyceridemia had significantly lower HOMA-β and FPIR, and higher plasma levels of TXNIP. There was also a negative correlation between TXNIP and HOMA-β or FPIR, and a positive correlation between TXNIP and HOMA-IR. CONCLUSIONS These data showed that the level of TXNIP is increased in patients with IGR and patients with both IGR and hypertriglyceridemia, islet β-cell dysfunction was related to the increased TXNIP in IGR patients.