Repeated ingestion of the leaf extract from Morus alba reduces insulin resistance in KK-Ay mice

The objective of this study was to test the hypothesis that repeated ingestion of diet containing the leaf extract from a Morus alba (LEM) maintains the postprandial hypoglycemic response and suppresses the progression of insulin resistance in high-sucrose diet fed KK-Ay mice with spontaneous type 2 diabetes mellitus (DM). This hypothesis is based on our previous studies where LEM competitively inhibited intestinal disaccharidases and suppressed the elevation of postprandial plasma glucose and insulin levels. Ten KK-Ay mice in each group were raised on 0%, 3%, or 6% LEM powder containing high-sucrose diets for 8 weeks. Blood samples were collected to measure fasting plasma glucose and insulin levels at weeks 2, 4, and 7 after the start of feeding. Urinary glucose excretion was monitored as a parameter of insulin resistance in 3-day intervals. Fasting plasma glucose level and urinary glucose excretion were significantly lower in both 3% and 6% LEM groups compared with the control group throughout the experiment. The plasma insulin of the 6% LEM group was significantly lower compared with the 3% LEM and control groups. Maintenance of low blood glucose and insulin delayed the onset time of urinary glucose excretion and were reflected by the ratio of additional LEM to sucrose in the diet. We observed the suppressive effects on the progression of hyperglycemia and hyperinsulinemia in the repeated ingestion of the LEM-containing diet. Namely, repeated ingestion of the LEM-containing diet reduces insulin resistance and may delay the appearance of DM, especially type 2 DM. Therefore, daily intake of LEM may be suitable for the prevention of obesity and DM. (C) 2011 Elsevier Inc. All rights reserved.