Dietary fibre has a beneficial effect on metabolic syndrome, e.g. by influencing the absorption of glucose. The source and structure of fibre affect the glucose response. In this study, the glycaemic and insulinaemic response to oat bread, oat bread with lingonberry fibre, oat-buckwheat bread and buckwheat porridge were tested in a small-scale clinical study (KHSHP E514/09). Nine healthy volunteers consumed test foods after overnight fasting. Serum glucose and C-peptide levels were determined by colorimetric and ELISA methods, respectively, from samples taken at seven time points during 120 min. The mean glycaemic and C-peptide indexes (C-pepIs) were 32 and 100 for oat bread, 47 and 119 for oat-lingonberry fibre bread, 58 and 105 for oat-buckwheat bread and 71 and 77 for buckwheat porridge. Similar to rye, buckwheat porridge having a relatively high glycaemic index (GI) tended to have a low C-pepI. Buckwheat and lingonberry fibres provide new alternatives for low GI foods.