METABOLIC RESPONSES TO HIGH-CARBOHYDRATE BREAKFASTS IN OBESE PATIENTSWITH IMPAIRED GLUCOSE-TOLERANCE - COMPARISON OF MEALS CONTAINING DAIRY-PRODUCTS AND FRUITS VERSUS BREAD

Carbohydrate (CHO) enriched diets can improve glucose tolerance in hea lthy subjects but have controversial effects in NIDDM patients. Their effects on glucose metabolism are not clearly established in obese pat ients with impaired glucose tolerance (IGT) and might depend on their glycemic index (GI). For that reason, we compared the metabolic respon ses to 2 isocaloric CHO rich breakfasts with either a low GI (LGI) or a high GI (HGI) in 10 lean healthy controls (group I) and in 9 obese s ubjects with IGT (group II). The LGI breakfast contained dairy product s and fruits while the HGI breakfast was rich in bread. The 2 breakfas ts were allocated in a random order and the metabolic and hormonal res ponses were evaluated both over the post-prandial periods of the break fast and of the following lunch. Blood glucose concentrations were con tinuously monitored. Plasma insulin and counter regulatory hormones we re measured every 30 min for 360 min. Nutrient oxidation rates were ca lculated from respiratory exchange data obtained for 60 min in the pre and post-prandial periods. Blood glucose responses and metabolic resp onses in terms of oxygen consumption and CO2 production were similar i n the two groups after a LGI breakfast but became different after the HGI breakfast. In the two groups taken as a whole, changes in CHO oxid ation rates observed for 1 hour following the meal, were negatively co rrelated with the corresponding incremental areas of plasma glucose, t his effect being more marked in obese patients with IGT. Such a limita tion in CHO oxidation following a HGI CHO load could impair the glycog en cycle and favour fat synthesis. Consequently, breakfasts rich in da iry products and fruits are more recommended in obesity with IGT than breakfasts rich in bread. (C) 1997 Elsevier Science Inc.