High Blood Glucose After Starch Loading in Young Women With Small Increase in Salivary Amylase: Another Crucial Role of Postprandial Salivary Amylase.

Background: Salivary α-amylase plays a crucial role in the glucose metabolism. However, postprandial salivary α-amylase activity (SAA) and its relationship with blood glucose (BG) are poorly understood. Therefore, we investigated SAA and BG after starch loading in healthy young women. Methods: In 60 healthy non-obese young women, we investigated SAA, BG, and blood 3-hydroxybutyrate (3HB) after the consumption of 150 g rice (starch 48.8 g). Participants were classified into two groups based on the changes (Δ) in SAA from baseline at 60 min: small- and large-increase in ΔSAA groups (SI-ΔSAA and LI-ΔSAA). Results: BG levels were significantly higher at 60, 90, and 120 min in participants with SI-ΔSAA (n = 31) than LI-ΔSAA (n = 29). Baseline 3HB concentration was also higher in participants with SI-ΔSAA. ΔSAA at 60 min was most closely and inversely correlated with BG and ΔBG at 90 min (r = -0.53 and -0.50, both P < 0.0001). Generalized linear model analysis also indicated that ΔSAA at 60 min was the most predictive of ΔBG at 90 min. Conclusions: Higher levels of BG and ΔBG were observed after starch loading in healthy young women with smaller increase in salivary amylase, suggesting another crucial role of postprandial salivary amylase for the postprandial glucose metabolism.