Improvement of insulin resistance after diet with a whole-grain based dietary product: results of a randomized, controlled cross-over study in obese subjects with elevated fasting blood glucose

Abstract

Subjects with obesity and elevated fasting blood glucose are at high risk of developing type 2 diabetes which may be reduced by a dietary intervention leading to an improvement of insulin resistance. We investigated the potential of a whole-grain based dietary product (WG) with reduced starch content derived from double-fermented wheat during a hypo-energetic diet to positively influence body weight, fasting blood glucose, insulin resistance and lipids in comparison to a nutrient-dense meal replacement product (MR) in a randomized two-way cross-over study with two 4-week treatment periods separated by a 2-week wash-out. Subjects replaced at least two daily meals with WG and MR, respectively, targeting for a consumption of 200 g of either product per day. Total daily energy intake was limited to 7120 kJ. Thirty-one subjects (BMI 33·9 (sd 2·7) kg/m2, fasting blood glucose 6·3 (sd 0·8) mmol/l) completed the study. In both treatment groups body weight ( − 2·5 (sd 2·0) v. − 3·2 (sd 1·6) kg for WG v. MR), fasting blood glucose ( − 0·4 (sd 0·3) v. − 0·5 (sd 0·5) mmol/l), total cholesterol ( − 0·5 (sd 0·5) v. − 0·6 (sd 0·5) mmol/l), TAG ( − 0·3 (sd 0·9) v. − 0·3 (sd 1·2) mmol/l) and homeostasis model assessment (HOMA) insulin resistance score ( − 0·7 (sd 0·8) v. − 1·1 (sd 1·7) μU/ml ×  mmol/l) improved (P < 0·05) with no significant differences between the treatments. After statistical adjustment for the amount of body weight lost, however, the comparison between both groups revealed that fasting serum insulin (P = 0·031) and HOMA insulin resistance score (P = 0·049) improved better with WG than with MR. We conclude that WG favourably influences metabolic risk factors for type 2 diabetes independent from the amount of body weight lost during a hypo-energetic diet.