Salivary protein glycosylation as a noninvasive biomarker for assessment of glycemia

Background: Assessment of short-term glycemic control can facilitate monitoring of diabetes development in at-risk individuals and monitoring response to lifestyle modification or medication. We evaluated salivary protein glycosylation levels as a novel, noninvasive, short-term glycemic index in comparison to hemoglobin A1c (HbA1c), fructosamine, 1,5-Anhydroglucitol (1,5-AG), and continuous glucose monitoring (CGM). Methods: Ten subjects with type 2 diabetes were monitored by CGM and saliva and blood were collected at baseline and days 1, 7, 14, 21, and 28 for determination of salivary protein glycosylation, serum fructosamine, and serum 1,5-Anhydroglucitol (1,5-AG) levels, as well as HbA1c (baseline and day 28). Weekly, 14-day, 21-day, and 28-day summary blood glucose measures from CGM were computed and matched to the time of each study visit. Results: Salivary protein glycosylation exhibited a moderate correlation with fructosamine (r = .65) and 1,5-AG (r = -.48) at baseline, and weak correlation with HbA1c (r = .3). Conclusions: Salivary protein glycosylation exhibited a stronger correlation than fructosamine and 1,5-AG with 7-, 14-, and 21-day average BG (r = .84, .84, and .69, respectively, vs -.37, -.28, and .00 [fructosamine] and .00, -.21, and -.57 [1,5-AG]), maximum BG (r = .79, .76, and .53 vs -.09, -.21, and -.05 [fructosamine] and -.32, -.27, and -.52 [1,5-AG]), and percentage of time over 140 mg/dL (r = .87, .79, and .59 vs -.26, -.32, and .07 [fructosamine] and -.04, -.10, and -.50 [1,5-AG]). Salivary protein glycosylation represents a promising noninvasive technology for monitoring short-term glycemic control.