Egg White Hydrolysate Improves Glucose Tolerance in Type-2 Diabetic NSY Mice

We have previously reported that chicken egg white (EW) and low-allergenic EW hydrolysate (EWH) suppressed ectopic fat accumulation and improved serum glucose and insulin levels. In this study, the dietary effects of EW and EWH on glucose tolerance were investigated in different ways to clarify the effect of EW and EWH on intestinal glucose absorption. Type 2 diabetic Nagoya-Shibata-Yasuda mice were divided into four groups: a low-fat and low-sucrose casein-based diet group (NL); high-fat and high-sucrose (HFS) casein-based diet group (NH); HFS EW-based diet group (NE); and HFS EWH-based diet group (NEH). Mice were fed their respective diets for 8 wk. At the end of the 6th and 7th week, an oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were respectively conducted in experiment A. At the end of the 7th week, an intraperitoneal glucose tolerance test (ipGTT) was conducted in experiment B. In experiment A, the plasma glucose level was suppressed in the NE group during both OGTT and ITT, and suppressed in the NEH group during OGTT, but not during ITT. In experiment B, the plasma glucose level was similarly suppressed in the NEH group during ipGTT, but the suppressive effect was weakened compared to OGTT. Plasma insulin level was lower in the NE and NEH groups in both experiments. Fecal triacylglycerol excretion was increased in the NE and NEH groups in experiment A and liver triacylglycerol content was suppressed in the NE group in experiment B. These findings suggested that in addition to improving fat metabolism, EWH improves glucose tolerance via mechanisms related and unrelated to small intestinal function.