Effect of lactulose on carbohydrate metabolism and diabetes mellitus

Background: Unabsorbable disaccharides, by reducing transit time and possibly glucose absorption, are expected to affect carbohydrate metabolism. Aim: To test the effects of a preparation containing fibre and lactulose in the form of biscuits on glucose and insulin levels in obesity. Methods: In 10 obese patients glucose and insulin were measured in the fasting state and in response to a meal during two consecutive days on a strictly controlled diet; on one day a total of 11 biscuits (10 g dietary fibre, 2 g raw fibre + 8.2 g lactulose) were randomly substituted for an equicaloric part of a diet. Results: Glucose and insulin in response to breakfast and to lunch were blunted by dietary fibre and lactulose, without any trend towards post-meal hypoglycaemia. Average day-time glucose decreased by 0.53 +/- SD 0.28 mmol/L, and insulin by 74.6 +/- 45.2 pmol/L. Plasma amino acids were higher during supplementation, ruling out malabsorption as a cause of glucose flattening. Conclusion: Because of the rationale of the preparation, good compliance of patients: and significant results in short-term experiments, the association of fibre and lactulose deserves more careful evaluation in long-term clinical studies.