Characteristics of some wheat-based foods of the Italian diet in relation to their influence on postprandial glucose metabolism in patients with type2 diabetes

The present study was aimed at evaluating in patients with type 2 diabetes: (1) the glycaemic response to four starchy foods based on wheat, typical o f the Italian diet; (2) the importance of some food characteristics in rela tion to their effects on postprandial glucose response. Seventeen patients with type 2 diabetes (eleven men and six women) participated in the study. All patients consumed, in random order and on alternate days, 50 g availabl e carbohydrate provided by 90 g white bread and, according to a randomised procedure, an equivalent amount of carbohydrate provided by one (n 8) or tw o (n 9) of three other different test foods (g): pizza 85, potato dumplings 165, hard toasted bread 60. Foods had a similar nutrient composition. Plas ma glucose response, measured for 180 min, was significantly lower after th e potato dumplings than after white bread at 90 (P < 0.05), 120 (P < 0.01) and 150 (P < 0.05) min. No difference was observed in postprandial plasma i nsulin response after the various test foods. The percentage of starch hydr olysed after 5 h in vitro hydrolysis with a-amylase was about 30 % lower fo r potato dumplings than for the other foods. However, no differences in the resistant starch content, the rate of diffusion of simple sugars added to a dialysis tube containing the food, and the viscosity of digesta were obse rved among the test foods. Scanning electron microscopy of potato dumplings showed a compact structure compatible with impaired accessibility of starc h to digestive enzymes. In conclusion, carbohydrate-rich foods typical of t he Italian diet which are often consumed as an alternative to pasta dishes are not equivalent in terms of metabolic impact in diabetic patients. Due t o their low blood glucose response, potato dumplings represent a valid alte rnative to other starchy foods in the diabetic diet. Food structure plays a n important role in determining starch accessibility to digestion, thus inf luencing the postprandial blood glucose response.