[Research on consistency of different measurement methods for saliva 1,5-anhydroglucitol]

Objective: To evaluate the consistency of different measurement methods of saliva 1,5-anhydroglucitol (1,5-AG) in different glucose metabolism populations. Methods: From January 2018 to June 2019, 175 healthy volunteers (21-65 years, 58 males and 117 females) with normal glucose tolerance (NGT) and 80 diabetic patients (18-70 years, 44 males and 36 females) were enrolled in Shanghai Jiao Tong University Affiliated Sixth People's Hospital. Saliva was collected by saliva collection tube, and 1,5-AG was measured using both enzymatic and mass spectrometry methods. Serum 1,5-AG was determined by enzymatic method. Results: In NGT subjects, both serum and saliva 1,5-AG levels detected by enzymatic method were positively correlated with the saliva 1,5-AG levels detected by liquid chromatography-mass spectrometry (r=0.247 and 0.523, respectively, both P<0.05). However, there was no significant correlation between saliva and serum 1,5-AG levels detected by enzymatic method (r=-0.074, P=0.333). In diabetic patients, both serum and saliva 1,5-AG levels detected by enzymatic method were positively correlated with the saliva 1,5-AG levels detected by gas chromatography-mass spectrometry (r=0.284 and 0.423, respectively, both P<0.05). However, there was no significant correlation between saliva and serum 1,5-AG levels detected by enzymatic method (r=-0.079, P=0.487). Conclusions: Both serum and saliva 1,5-AG levels detected by enzymatic method have a good consistency with saliva 1,5-AG levels detected by mass spectrometry method. The saliva and serum 1,5-AG levels detected by enzymatic method are not well correlated, and thus the enzymatic detection of saliva 1,5-AG needs further improvement in clinical practice.