Serum γ-glutamyltransferase in obstructive sleep apnea hypopnea syndrome and its role in predicting concomitant diabetes mellitus

Abstract

To determine the association of obstructive sleep apnea hypopnea syndrome(OSAHS) with serum γ-glutamyltransferase(γ-GT) and whether serum γ-GT is an independent predictor for diabetes mellitus(DM) in OSAHS patients. A total of 172 Han Chinese subjects were enrolled and divided into three groups based on full-night polysomnography(PSG): severe OSAHS group(AHI>30 events/h), mild to moderate OSAHS group (5<AHI≤30 events/h) and control group(AHI<5 events/h). Serum γ-GT levels were measured after an overnight fast and measurements were compared among groups.Stepwise multiple linear regressions were conducted to determine the independent linear correlation of serum γ-GT with PSG parameters.In subgroup analysis, serum γ-GT levels were further compared between OSAHS with DM and without DM group.DM prevalence was compared between high-γ-GT and low-γ-GT OSAHS group.Binary logistic regressions were conducted to determine the role of serum γ-GT in predicting DM prevalence in OSAHS patients. Serum γ-GT levels in OSAHS groups were higher than those in control group(25.00, 34.00 and 42.50 IU/L respectively in control, mild to moderate and severe OSAHS group, P=0.001). Serum γ-GT levels were positively correlated with oxygen desaturation index(ODI) in stepwise multiple linear regressions(Beta=0.185, P=0.024). In subgroup analyses, serum γ-GT levels were higher in OSAHS patients with DM than in those without DM (P=0.006). The prevalence of DM was higher in high-γ-GT than in low-γ-GT OSAHS group (P=0.030). Logistic regressions showed that serum γ-GT was an independent predictor for DM prevalence in OSAHS patients(OR=1.011, P=0.033). Serum γ-GT level increases with OSAHS severity and correlates independently with oxygen desaturation during sleep.Serum γ-GT is an independent predictor for DM prevalence in OSAHS patients.