Elevated postprandial glycaemia has been linked to CVD in a number of different epidemiological studies involving predominantly non-diabetic volunteers. The MiniMed continuous glucose monitor, which measures blood glucose every 5 min, over a 24 h period, was used to investigate changes in blood glucose readings before and after instigating a diet with low glycaemic index (GI) for 1 week in free-living healthy individuals. Nine healthy people (age 27 (sem 1·3) years, BMI 23·7 (sem 0·7) kg/m2, one male, eight females) completed the study. A reduction in GI (59·7 (sem 2) v. 52·1 (sem 2), P<0·01) occurred in all nine subjects while energy and other macronutrients remained constant. A significant reduction was also observed in fasting glucose at 06·00 hours (5·4 (sem 0·2) v. 4·4 (sem 0·3) mmol/l, P<0·001), mean glucose (5·6 (sem 0·2) v. 5·1 (sem 0·2) mmol/l, P=0·004), area under the 24 h glucose curve (8102 (sem 243) v. 750 (sem 235) mmol/l per min, P=0·004) and area under the overnight, 8 h glucose curve (2677 (sem 92) v. 2223 (sem 121) mmol/l per min, P=0·01). The present study provides important data on how a simple adjustment to the diet can improve glucose profiles that, if sustained in the long term, would be predicted from epidemiological studies to have a favourable influence on CVD.