BACKGROUND Large postprandial glucose peaks are associated with increased risk of diabetic complications and cardiovascular disease. OBJECTIVE We investigated the effect of carbohydrate distribution on postprandial glucose peaks with continuous blood glucose monitoring (CGMS), when consuming a moderate carbohydrate diet in energy balance in subjects with type 2 diabetes. METHODS Twenty-three subjects with type 2 diabetes were randomly assigned to each of four 3-d interventions in a crossover design with a 4-d washout period. Identical foods were provided for each treatment with a ratio of total carbohydrate to protein to fat of 40%:34%:26% but differing in carbohydrate content at each meal: even distribution (CARB-E; approximately 70 g carbohydrate), breakfast (CARB-B), lunch (CARB-L), and dinner(CARB-D), each providing approximately 125 g carbohydrate in the loaded meal in a 9-MJ diet. Glucose concentrations were continuously measured with CGMS. Outcomes were assessed by postprandial peak glucose (G(max)), time spent > 12 mmol/L (T > 12), and total area under the glucose curve (AUC(20)). RESULTS Daily G(max) differed between treatments (P = 0.003) with CARB-L (14.2 +/- 1.0 mmol/L), CARB-E (14.5 +/- 0.9 mmol/L), and CARB-D (14.6 +/- 0.8 mmol/L) being similar but lower than CARB-B (16.5 +/- 0.8 mmol/L). Meal G(max) was weakly related to carbohydrate amount and glycemic load (r = 0.40-0.44). T > 12 differed between treatments (P = 0.014), and a treatment x fasting blood glucose (FBG) interaction (P = 0.003) was observed with CARB-L (184 +/- 74 min) < CARB-B (190 +/- 49 min) < CARB-D (234 +/- 87 min) < CARB-E (262 +/- 91 min). Total AUC(20) was not significantly different between treatments. After adjustment for FBG, treatment became significant (P = 0.006); CARB-L (10 049 +/- 718 mmol/L x 20 h) < CARB-E (10 493 +/- 706 mmol/L x 20 h) < CARB-B (10 603 +/- 642 mmol/L x 20 h) < CARB-D (10 717 +/- 638 mmol/L x 20 h). CONCLUSIONS CARB-E did not optimize blood glucose control as assessed by postprandial peaks, whereas CARB-L provided the most favorable postprandial profile.