Improving Effect of the Acute Administration of Dietary Fiber-Enriched Cereals on Blood Glucose Levels and Gut Hormone Secretion

Abstract

Dietary fiber improves hyperglycemia in patients with type 2 diabetes through its physicochemical properties and possible modulation of gut hormone secretion, such as glucagon-like peptide 1 (GLP-1). We assessed the effect of dietary fiber-enriched cereal flakes (DC) on postprandial hyperglycemia and gut hormone secretion in patients with type 2 diabetes. Thirteen participants ate isocaloric meals based on either DC or conventional cereal flakes (CC) in a crossover design. DC or CC was provided for dinner, night snack on day 1 and breakfast on day 2, followed by a high-fat lunch. On day 2, the levels of plasma glucose, GLP-1, glucose-dependent insulinotropic polypeptide (GIP), and insulin were measured. Compared to CC, DC intake exhibited a lower post-breakfast 2-hours glucose level (198.5±12.8 vs. 245.9±15.2 mg/dL, P<0.05) and a lower incremental peak of glucose from baseline (101.8±9.1 vs. 140.3±14.3 mg/dL, P<0.001). The incremental area under the curve (iAUC) of glucose after breakfast was lower with DC than with CC (P<0.001). However, there were no differences in the plasma insulin, glucagon, GLP-1, and GIP levels. In conclusion, acute administration of DC attenuates postprandial hyperglycemia without any significant change in the representative glucose-regulating hormones in patients with type 2 diabetes (ClinicalTrials.gov. NCT 01997281).

Trial registration: ClinicalTrials.gov NCT01997281.

Keywords: Diabetes Mellitus, Type 2; Dietary Fiber; Incretins, Glucagon-like Peptide 1.

Fig. 1. Study procedures. Meals based on cereal flakes were given at 6 p.m. and 10 p.m. on day 1 and 8 a.m. on day 2, followed by a high-fat lunch meal at noon. On day 2, serial blood samples were obtained from 8 a.m. (0 hour) to 4 p.m. (8 hours), and postprandial changes in the plasma glucose, GLP-1, GIP, insulin, glucagon, and serum NEFA levels were measured. GLP-1, Glucagon-like peptide 1; GIP, gastric inhibitory polypeptide; NEFA, non-esterified fatty acid.

Fig. 2. Changes in the plasma glucose and NEFA levels. Postprandial glucose levels (A), postprandial peak glucose levels (B), iAUCs of postprandial glucose levels during 0-4 hours interval (C), and postprandial NEFA levels (D) are shown. ^*P < 0.05; ^†P < 0.001. iAUC, incremental area under the curve; CC, conventional cereal; DC, dietary fiber-enriched cereal; NEFA, nonesterified fatty acid; n.s., no significance.

Fig. 3. Change in the plasma insulin and glucagon levels. Postprandial insulin (A) and glucagon (C) levels and postprandial iAUCs of insulin (B) and glucagon (D) during 0-4 hours interval are shown. iAUC, incremental area under the curve; CC, conventional cereal; DC, dietary fiber-enriched cereal; n.s., no significance.

Fig. 4. Change in plasma total GLP-1 and GIP levels. Postprandial GLP-1 (A) and GIP (C) levels and postprandial iAUCs of GLP-1 (B) and GIP (D) during the 0 to 4 hours and 4 to 8 hours intervals are shown. iAUC, incremental area under the curve; CC, conventional cereal; DC, dietary fiber-enriched cereal; GLP-1, glucagon-like peptide 1; GIP, gastric inhibitory polypeptide; n.s., no significance.