Study objective-To determine the effect on the glycaemic response to bread of the ratio of whole cereal grains to milled flour.Design-Randomised assignment of groups of diabetic volunteers to test and control meals, taken after an overnight fast. Test foods were also analysed for in vitro digestion with human saliva.

Plasma glucose concentrations measured 2 h after DSP administration are closely related to those measured 2 h after the GTT but are more consistent than the 2-h post-GTT concentrations within the critical IGT range. This finding suggests that measurement of plasma glucose 2 h after administration of the DSP may allow more precise discrimination among normal glucose levels, IGT, and diabetes than measurement of plasma glucose 2 h after the GTT.

No abstract

Unexpected plasma glucose responses to different mixed meals fed to normal and diabetic volunteers have recently been reported. We have therefore examined in normal volunteers the effect of mixing carbohydrate foods of different glycemic indices (GIs) without the addition of fat and protein. The observed GI of the mixed meal was within 2% of the expected value. In studies in the literature where fat and protein were added to mixed meals, the observed blood glucose responses also related significantly to the meal GIs calculated from the individual foods. Addition of fat and protein in the quantities used did not obscure this relationship. Studies to determine sources of error in comparing glycemic responses showed that type II diabetic patients displayed the least within-individual variation, and type I diabetic patients the most. Expression of results as the GI rather than as absolute glycemic response areas reduced by 50% the between-subject variation. The mean GI values of rice tested in type I and type II patients were similar (82 +/- 22 compared with 74 +/- 19) and the reproducibility 22 mo later in the same group of subjects was excellent (81 +/- 15 compared with 83 +/- 15). However, the lack of precise GI values for all foods fed in the test meals indicates a need for GI values to be derived for a wider range of individual foodstuffs. The GI approach to classifying foods according to physiologic effect may play a useful role in planning meals and diets in which specific blood glucose profiles are required.

A significant relationship was found between the rate of release of the sugars; glucose, maltose, and maltotriose from amylitic digestion of 10 foods tested in vitro (expressed as the digestibility index) and the blood glucose response to 50-g carbohydrate portions of the same foods eaten by diabetics (expressed as the glycemic index), (r = 0.815, n = 10, p greater than 0.01). The glycemic index related to both the palatability of the foods (r = 0.731, p less than 0.05) and their frequency of use (r = 0.698, p less than 0.05). However, in this group of motivated diabetics food use was not related directly to palatability, but rather to health belief (r = 0.689, p less than 0.05). The results suggest that carbohydrate foods of potential use to the diabetic may be identified by their in vitro digestion characteristics but to a large extent their acceptance will depend on health belief and possibly ease of preparation.