Comparison of the effects of slowly and rapidly absorbed carbohydrates on postprandial glucose metabolism in type 2 diabetes mellitus patients: a randomized trial

Background: Isomaltulose attenuates postprandial glucose and insulin concentrations compared with sucrose in patients with type 2 diabetes mellitus (T2DM). However, the mechanism by which isomaltulose limits postprandial hyperglycemia has not been clarified. Objective: The objective was therefore to assess the effects of bolus administration of isomaltulose on glucose metabolism compared with sucrose in T2DM. Design: In a randomized, double-blind, crossover design, 11 participants with T2DM initially underwent a 3-h euglycemic-hyperinsulinemic (0.8 mU kg(-1) . min(-1)) clamp that was subsequently combined with 1 g/kg body wt of an oral C-13-enriched isomaltulose or sucrose load. Hormonal responses and glucose kinetics were analyzed during a 4-h postprandial period. Results: Compared with sucrose, absorption of isomaltulose was prolonged by similar to 50 min (P = 0.004). Mean plasma concentrations of insulin, C-peptide, glucagon, and glucose-dependent insulinotropic peptide were similar to 10-23% lower (P < 0.05). In contrast, glucagon-like peptide 1 (GLP-1) was similar to 64% higher (P < 0.001) after isomaltulose ingestion, which results in an increased insulin-to-glucagon ratio (P < 0.001) compared with sucrose. The cumulative amount of systemic glucose appearance was similar to 35% lower after isomaltulose than after sucrose (P = 0.003) because of the reduction in orally derived and endogenously produced glucose and a higher first-pass splanchnic glucose uptake (SGU). Insulin action was enhanced after isomaltulose compared with sucrose (P = 0.013). Conclusions: Ingestion of slowly absorbed isomaltulose attenuates postprandial hyperglycemia by reducing oral glucose appearance, inhibiting endogenous glucose production (EGP), and increasing SGU compared with ingestion of rapidly absorbed sucrose in patients with T2DM. In addition, GLP-1 secretion contributes to a beneficial shift in the insulin-to-glucagon ratio, suppression of EGP, and enhancement of SGU after isomaltulose consumption. This trial was registered at clinicaltrials.gov as NCT01070238.