The effects of a high-fat meal challenge with polyphenol and fiber on postprandial insulin and C-peptide in prediabetics: A pilot study

The purpose of the present study was to understand the effects of varying levels of polyphenols and fiber on postprandial C-peptide and insulin levels after consumption of a high fat, high sugar meal (HFHSM) in prediabetic individuals. All subjects were diagnosed as pre-diabetic within 3 months of the start date of the study by a medical professional or were screened as meeting one of the criteria for prediabetes by researchers within the James Madison Human Performance Lab by a HbA1c (5.7-6.4%), fasting glucose (100-126 mg/dL), or an oral glucose tolerance test (OGTT; 140-199 mg/dL). After an overnight fast, five females (56.9 ± 12.8 y) completed four HFHSM challenges in a randomized order and were similar in caloric density and macronutrient count 1) HFHSM control that was low in polyphenol and fiber (LPLF), 2) HFHSM that was high in polyphenol and fiber (HPHF), 3) HFM that was high in polyphenol and low in fiber (HPLF), 4) HFHSM that was low in polyphenol and high in fiber (LPHF) (12 kcal/kg body weight). Blood samples were taken at baseline, every 30 minutes for two hours, and every hour for 6 hours after consumption of the HFHSM condition. Glucose was increased above baseline in the LPLF and HPHF conditions, while it remained at baseline in the HPLF and LPHF conditions. Insulin was elevated above baseline in the LPLF condition at timepoints 30 min through 240 min (p<0.002). While, in the LPHF condition no increase in insulin above baseline occurred (p<0.05). During timepoints 90 min and 120 min insulin was elevated in the LPLF when compared to the LPHF condition (p<0.03). The LPHF condition displayed the least amount of timepoints for C-Peptide elevated above baseline (60 min-120 min; p<0.05). This evidence suggests that the fiber had a greater impact on reducing post-prandial levels after consumption of a HFHSM than the polyphenols. More research is needed to understand how polyphenol and fiber affect the post-prandial response after consumption of a HFHSM.