A Mediterranean-pattern Meal Increases GLP-1 and Oxyntomodulin more than an energy-matched High Fiber Plant-based meal in Type-2 Diabetes patients: A Crossover, Randomized, Controlled Inpatient Physiology Study

Background: Type-2 diabetes (T2D) is a multifactorial metabolic burden whose metabolic features include alterations in GLP-1 secretion and ultimately hunger/satiety circuit derangement. Manipulating the composition of the diet in order to promote GLP-1 secretion may represent a promising lifestyle strategy for obesity and T2D management. Aims: The objective of this study was to assess the post-prandial profile of appetite regulating hormones and assessing the post-prandial appetite ratings using a Visual Analogue Scale (VAS), as well as measuring the fasting and postprandial glucose/insulin responses in overweight and/or obese, well controlled patients with T2D. Materials and Methods: Twelve T2D patients (M:F = 7:5) aged 63.1 ± 8.5 years were enrolled in a randomized, controlled, crossover trial. Subjects consumed on two different days, at one-week interval, an experimental High Fiber Vegetarian meal (HFV) rich in dietary carbohydrate and fiber in comparison with a standard, Mediterranean-like meal (MED). The two meals were isocaloric. Appetite ratings, glucose/insulin and gastrointestinal hormone responses were assessed either at fasting and every 30' until 210' for GLP-1 and Oxyntomodulin and 240’ for glucose and insulin after the ingestion of the meal. Subjects consuming the MED meal exhibited significant and higher levels of GLP-1 and oxyntomodulin across the 210' compared to the HFV group (p <.05 one-sided for both the hormones). The 210'-GLP-1 and Oxyntomodulin AUC were significantly increased in the MED group (P <.022 and P <.023, respectively). Both the MED and HFV meals consumption induced a biphasic shaped secretion pattern over time but the MED consumption produced a significant delayed second GLP-1 peak at 150' compared to the HFV meal (56 ± 21 pg/mL Vs 44 ± 18 pg/mL, respectively P <.05), delaying the second peak one hour and half after the HFV-M group. The MED group maintained significant and consistent decreased levels of plasma over time compared to the HFV group (P <.039) and the 240-minute glycemic AUC was significantly higher in the HFV compared to the MED meal, even after the adjustment for age and gender, BMI and HbA1c (P <.006). In addition, the 240-minute glycemic iAUC was significantly higher in the MED meal (P <.002). No major significant changes in VAS and postprandial insulin profile between the two groups were assessed. Conclusions: A Mediterranean type of meal is more effective in increasing postprandial secretion of GLP-1 and oxyntomodulin and reducing postprandial plasma glucose levels in overweight/obese T2D patients. These changes did not influence the appetite ratings evaluated through the visual analogue scale. These findings suggest that, in acute, diet-related endocrine release may not be related to changes in self-rated hunger/satiety, possibly because of T2D metabolic features. Either on short and long term, diet influences gut hormone levels in T2D.