Objectives　The aim of this study was to evaluate the effectiveness of indigestible dextrin-containing tea beverage on the postprandial increase in blood glucose level in subjects with relatively higher postprandial blood glucose levels in a randomized, placebo-controlled, double-blind, crossover study.
Methods　The trial was conducted with 60 Japanese subjects with fasting glucose levels less than 126 mg/dL and a 30-min postprandial blood glucose level ranging 140-199 mg/dL. Subjects consumed either a test beverage containing 5 g（as dietary fiber）of indigestible dextrin or a placebo beverage without indigestible dextrin together with a high carbohydrate meal, and the levels of blood glucose and insulin were determined before and 30-120 min after the meal.
Results　When the subjects ingested test beverage, postprandial increase in the level of blood glucose was low compared to that when the subjects ingested placebo beverage. The area under the curve（AUC）for blood glucose levels was 288.6±43.4 mg・h/dL for test beverage and 299.6±37.1 mg・h/dL for placebo; P＝0.048, and the maximum blood glucose level between 0 and 120 min following the test meal was 171.8±27.1 mg/dL for test beverage and 178.8±24.5 mg/dL for placebo（P＝0.035）. There was no serious adverse event related to the ingestion of test beverage.
Conclusions　Our findings suggest that the consumption of test beverage containing 5 g（as dietary fiber）of indigestible dextrin suppresses postprandial increase in blood glucose level in subjects with relatively higher fasting blood glucose levels.