Intra- and inter-individual variation in blood glucose response to white bread and glucose in patients with type 2 diabetes mellitus

Lara Krüger, Marthinette Slabber, Gina Joubert, Christine S Venter, Hester H Vorster

Abstract


Introduction and objective: Variability of glycaemic response can be due to several factors, including within- and betweensubject variations. The aim of this study was to determine the within- and between-subject variation of fasting free fatty acids (FFAs), plasma glucose and serum insulin after the intake of white bread versus oral glucose in type 2 diabetic subjects. Methods: Nine overnight-fasted subjects (4 men and 5 women, mean body mass index (BMI) 31.7, mean age 57.8 years) with type 2 diabetes mellitus were recruited. Each subject received a standard pre-test meal the evening before every test day. The reference foods used were 50 g available carbohydrate is in the form of white bread (101 g), and glucose. Each reference food was tested on four randomised occasions. Venous blood samples were taken before, and every 30 minutes for 3 hours after, test meals. Incremental areas under the curve (IAUC), areas from the lowest value (AUCL) and areas from zero (AUC0) were calculated for the glycaemic and insulin response curves. Results: No significant difference (p < 0.05) for within-subject variation in plasma glucose response was found at any time point, while the coefficient of variation (CV) of the IAUC and AUCL were significantly higher for white bread. The only significant difference (p > 0.05) in plasma glucose response between the subjects was found at 180 minutes, while no significant differences were found between the variations according to the areas under the curve. No significant differences were found between glucose and white bread with regard to within and between-subject variation for serum insulin responses and fasting FFA concentrations. Conclusion: According to the IAUC (used in glycaemic index (GI) calculations), within-subject blood glucose concentrations tend to be less variable after a glucose test meal than after a starchy test meal in type 2 diabetic subjects.

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