Postprandial Glucose Regulation Research Articles

A Narrative Review of the Interplay Between Carbohydrate Intake and Diabetes Medications: Unexplored Connections and Clinical Implications

This narrative review examines the dynamic interplay between carbohydrate intake and diabetes medications, highlighting their combined molecular and clinical effects on glycemic control. Carbohydrates, a primary energy source, significantly influence postprandial glucose regulation and necessitate careful coordination with pharmacological therapies, including insulin, metformin, glucagon-like peptide (GLP-1) receptor agonists, and sodium-glucose cotransporter-2 (SGLT2) inhibitors. Low-glycemic-index (GI) foods enhance insulin sensitivity, stabilize glycemic variability, and optimize medication efficacy, while high-GI foods exacerbate glycemic excursions and insulin resistance. Continuous glucose monitoring (CGM) offers real-time insights to tailor dietary and pharmacological interventions, improving glycemic outcomes and reducing complications. Despite advancements, gaps persist in understanding nutrient–drug interactions, particularly with emerging antidiabetic agents. This review underscores the need for integrating carbohydrate-focused dietary strategies with pharmacotherapy to enhance diabetes management. Future research should prioritize clinical trials leveraging CGM technology to explore how glycemic index, glycemic load, and carbohydrate quality interact with newer diabetes medications. Such studies can refine evidence-based recommendations, support individualized care plans, and improve long-term outcomes. Addressing systemic barriers, such as limited access to dietitians and CGM technology in underserved regions, is critical for equitable care. Expanding the roles of community health workers and training healthcare providers in basic nutrition counseling can bridge gaps, promoting sustainable and inclusive diabetes management strategies. These efforts are essential for advancing personalized, effective, and equitable care for individuals with diabetes.

Evaluation of the Effects of Non-Invasive Auricular Acupoint Stimulation on Postprandial Blood Glucose Regulation using a CGM Device

Background: Postprandial blood glucose regulation is critical for diabetes management. Non-invasive auricular acupoint stimulation may influence metabolic functions through the autonomic nervous system. This study aimed to evaluate its effects on postprandial glucose regulation using Continuous Glucose Monitoring (CGM). Methods: Thirteen healthy Japanese adults (10 males, 3 females) had 1.5 mm gold beads applied to six acupoints. Glucose levels were monitored over seven days using CGM. Key metrics included postprandial peak, 2-hour glucose levels, time to peak, and normalization time. Results: Auricular acupoint stimulation reduced time to glucose peak after breakfast (-14.6 min, p = 0.01) and glucose normalization time for breakfast and lunch combined (-20.8 min, p = 0.04). A significant reduction in 2-hour postprandial glucose was observed after lunch (-10.8 mg/dL, p = 0.03). No significant effect was found on peak glucose levels. Conclusion: Auricular acupoint stimulation may promote postprandial glucose normalization, particularly after breakfast and lunch, and could serve as a complementary approach to glucose management.

Nutrition and health effects of pectin: A systematic scoping review of human intervention studies.

Pectin is composed of a group of complex polysaccharides that are naturally found in various plants and are associated with a range of beneficial health effects. Health outcomes from dietary pectin can vary depending on botanical origin, dietary dose and structure of pectin. The objective of this scoping review is to build a comprehensive overview of the current evidence available on intervention studies conducted in humans and to better understand the possible knowledge gaps in terms of structure-function relationships across the different health-related effects. PubMed and Embase databases were searched using PRISMA-ScR guidelines, yielding 141 references (from the initial 3704), representing 134 intervention studies performed between 1961 and 2022 that met inclusion criteria. Studies were divided into six categories, which included gut health, glycaemic response and appetite, fat metabolism, bioavailability of micronutrients, immune response and other topics. Review of these human intervention studies identified a variety of cohort characteristics and populations (life stage, health status, country), sources/types of pectin (i.e. citrus, sugarbeet, apple, other and non-defined), intervention timeframes (from one single intake to 168 d) and doses (0.1-50 g/d) that were tested for health outcomes in people. Gut health, post-prandial glucose regulation and maintenance of blood cholesterol represented the largest categories of studied outcomes. Further research to strengthen the structure-function relationships for pectin with health properties and associated outcomes is warranted and will benefit from a more precise description of physico-chemical characteristics and molecular compositions, such as degree of esterification, weight, degree of branching, viscosity, gel formation and solubility.

Investigation of Anti-Diabetic Properties of Ceylon Cinnamon Bark Extracts by In-Vitro α-Amylase and α-Glucosidase Inhibition, Molecular Modeling, and Postprandial Blood Glucose Regulation for Potential Nutraceuticals

Background: Diabetes Mellitus (DM) can appear due to the absence of insulin (DM1- type 1) or poor response of cells to insulin (DM2-type 2). Even though DM1 cannot be controlled using general treatments, DM2 can be easily controlled or prevented using pharmaceuticals, nutraceuticals, or dietary practices. Ceylon cinnamon (Cinnamomum zeylanicum) is one such natural remedy that has been consumed against elevated blood glucose levels in the past. Cinnamon and different types of cinnamon extracts have been scientifically tested for their activities on the inhibition of α-amylase and α-glucosidase enzymes that are responsible for carbohydrate metabolism and are effective in blood glucose regulation. However, the combined effect of aqueous and ethanol extracts of cinnamon bark on blood glucose regulation is still lacking. In this study, Water Extract of Cinnamon (CWE), Ethanol Extracts of Cinnamon (hot ethanol extract of cinnamon-CHEE, cold ethanol extract of cinnamon-CEE, and 50% ethanol extract of cinnamon- CEE-50) were studied for their sugar-controlling properties. Objectives: This study was performed to identify the efficacy of different cinnamon extracts on the inhibition of α-amylase and α-glucosidase enzymes, followed by animal studies to confirm the use of the extracts in nutraceutical formulations. Methods: Water and ethanol-based extraction method was used to prepare cinnamon extracts. These extracts have been scientifically tested for their activities on the inhibition of α-amylase and α-glucosidase enzymes. Molecular docking studies were used to identify the binding of the active molecules to the substrate binding sites of α-amylase and α-glucosidase. In-vivo time dependence postprandial blood glucose regulation studies have been performed with healthy Wistar male rats. Results: Yields of the CHEE, CEE, and CWE were 14±2%, 12±2%, and 8±1% respectively. According to the LCMS data, the major component in the CEE was cinnamaldehyde. Both CWE and CEE were subjected to the Total Polyphenol assay (TPC) and Total Flavonoids (TFC) assays. The TPC of CWE and CEE were 117±1 mg (Gal)/g and 170±10 mg (Gal)/g, while the TFC of CWE and CEE were 359±1 mg (Qc)/g and 254±4 mg (Qc)/g, respectively. In the α-amylase inhibition assay, Acarbose; a known α-amylase inhibitor, and CEE showed IC50 values of 65.4 ppm and 2.6 ppm, while CWE failed to show inhibition against α-amylase. In the α-glucosidase inhibition assay, Acarbose; a known α-amylase inhibitor, CEE, and CWE showed IC50 values of 312 ppm, 4.5 ppm, and 1.3 ppm, respectively. In-vivo time dependence postprandial blood glucose regulation studies that have been performed with healthy Wistar male rats showed a lowering of blood glucose concentrations by 22%, 11%, and 10% of glucose at 30 min, 60 min, and 90 min compared to the control group. Conclusion: The CEE contains polyphenols and flavonoids and is effective in inhibiting both α- amylase and α-glucosidase. The CWE also contains polyphenols and a comparatively higher level of flavonoids and is effective in inhibiting α-glucosidase while not affecting α-amylase inhibition. Overall, the IC50 data, TPC data, and TFC data proposed that the inhibition of carbohydrate hydrolyzing enzymes by polyphenols may depend on the polarity of particular polyphenols. Based on the rat trials, it can be concluded that the 1:1 combination of CWE and CEE may be useful in formulating postprandial blood glucose level-regulating nutraceuticals.

The Evaluation of the Phytochemical Profiles and Antioxidant and α-Glucosidase Inhibitory Activities of Four Herbal Teas Originating from China: A Comparative Analysis of Aqueous and Ethanol Infusions.

Recent research has demonstrated the positive impact of herbal tea consumption on postprandial blood glucose regulation. This study conducts a comparative analysis of aqueous and ethanol extractions on four herbal teas (Mallotus, Cyclocarya, Rubus, and Vine) to assess their phytochemical profiles and functional attributes. Phytochemical contents, antioxidant activities, α-glucosidase inhibitory activities, and chemical compositions are investigated via colorimetric analyses and UPLC-Q-Orbitrap HRMS/MS, respectively. Results indicate that Vine, among the teas studied, exhibits the most pronounced glucose-regulating effects under both extraction methods. While ethanol extractions yield higher phytochemical content overall, the compositions vary. Conversely, aqueous extracts demonstrate unexpectedly potent antioxidant activities and comparable α-glucosidase inhibitory activities to ethanol extracts. Phytochemical contents correlate positively with antioxidant activities and α-glucosidase inhibitory activities. However, antioxidant activities exhibit a weak positive correlation with α-glucosidase inhibitory activities. These findings provide evidence that aqueous extracts from herbal teas contain valuable phytochemical compositions beneficial for antioxidants and individuals with hyperglycemia, suggesting their potential as functional ingredients to enhance the nutritional value of herbal food products.

Glucagon-like Peptide 1, Glucose-Dependent Insulinotropic Polypeptide, and Glucagon Receptor Agonists in Metabolic Dysfunction-Associated Steatotic Liver Disease: Novel Medication in New Liver Disease Nomenclature.

Glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are incretins that regulate postprandial glucose regulation, stimulating insulin secretion from pancreatic β-cells in response to food ingestion. Modified GLP-1 receptor agonists (GLP-1RAs) are being administered for the treatment of obesity and type 2 diabetes mellitus (T2DM). Strongly related to those disorders, metabolic dysfunction-associated steatotic liver disease (MASLD), especially its aggressive form, defined as metabolic dysfunction-associated steatohepatitis (MASH), is a major healthcare burden associated with high morbidity and extrahepatic complications. GLP-1RAs have been explored in MASH patients with evident improvement in liver dysfunction enzymes, glycemic control, and weight loss. Importantly, the combination of GLP-1RAs with GIP and/or glucagon RAs may be even more effective via synergistic mechanisms in amelioration of metabolic, biochemical, and histological parameters of MASLD but also has a beneficial impact on MASLD-related complications. In this current review, we aim to provide an overview of incretins' physiology, action, and signaling. Furthermore, we provide insight into the key pathophysiological mechanisms through which they impact MASLD aspects, as well as we analyze clinical data from human interventional studies. Finally, we discuss the current challenges and future perspectives pertinent to this growing area of research and clinical medicine.

Inhibitory effect and mechanism of tannic acid against two starch digestive enzymes

Abstract Backgrounds Tannic acid (TA), as a plant-derived phenolic substance, is involved in regulating the activity of starch digestive enzymes, but its underlying mechanism remains unclear. Methods and Results In the present study, inhibition rate and inhibition kinetics assays were performed and confirmed that TA had a strong inhibitory effect on both α-amylase and α-glucosidase with IC50 values of 0.1585 mg/mL and 0.00542 mg/mL, respectively, through a mixed inhibition mode. The secondary structures of both enzymes were confirmed to be modified by TA through circular dichroism (CD) spectra. Fluorescence quenching analysis revealed that the interaction between TA and two enzymes was a static process of pontaneous complex formation. Finally, molecular docking revealed that non-covalent bonds were the main interaction forces between TA and both enzymes. Conclusions Thus, TA was a promising candidate for the inhibition of starch-digesting enzymes, and the present research provided insight into postprandial glucose regulation through polyphenols.

Design of PD Controllers with Input Saturation for Postprandial Blood Glucose Regulation

An Artificial pancreas system regulates blood glucose in people with type 1 diabetes by automating the appropriate insulin infusion rate calculation. Insulin cannot be removed once injected, and thus, the control input is constrained to be positive. Controllers designed without taking this constraint into consideration often deliver an excessive insulin dose after a meal intake (postprandial period), which may cause hypoglycemia, a condition related to harmful complications. The non-negativeness is usually handled indirectly through additional control structures that compensate for the saturation by cutting of the insulin flow in advance. The few approaches that consider the non-negativeness of insulin in the controller design process end up with high-order controllers, which are difficult to analyze. In this work, the design of a input-constrained PD controller for regulating postprandial glucose is explored. The set of feasible controller parameters is computed and related to the meal and insulin dynamics.

Pre- Versus Postmeal Sedentary Duration—Impact on Postprandial Glucose in Older Adults With Overweight or Obesity

Introduction: Reducing sedentary time is associated with improved postprandial glucose regulation. However, it is not known if the timing of sedentary behavior (i.e., pre- vs. postmeal) differentially impacts postprandial glucose in older adults with overweight or obesity. Methods: In this secondary analysis, older adults (≥65 years) with overweight and obesity (body mass index ≥ 25 kg/m2) wore a continuous glucose monitor and a sedentary behavior monitor continuously in their real-world environments for four consecutive days on four separate occasions. Throughout each 4-day measurement period, participants followed a standardized eucaloric diet and recorded mealtimes in a diary. Glucose, sedentary behavior, and meal intake data were fused using sensor and diary timestamps. Mixed-effect linear regression models were used to evaluate the impact of sedentary timing relative to meal intake. Results: Premeal sedentary time was significantly associated with both the increase from premeal glucose to the postmeal peak (ΔG) and the percent of premeal glucose increase that was recovered 1-hr postmeal glucose peak (%Baseline Recovery; p < .05), with higher levels of premeal sedentary time leading to both a larger ΔG and a smaller %Baseline Recovery. Postmeal sedentary time was significantly associated with the time from meal intake to glucose peak (ΔT; p < .05), with higher levels of postmeal sedentary time leading to a longer time to peak. Conclusions: Pre- versus postmeal sedentary behavior differentially impacts postprandial glucose response in older adults with overweight or obesity, suggesting that the timing of sedentary behavior reductions might play an influential role on long-term glycemic control.

Inclusion of Oat Polar Lipids in a Solid Breakfast Improves Glucose Tolerance, Triglyceridemia, and Gut Hormone Responses Postprandially and after a Standardized Second Meal: A Randomized Crossover Study in Healthy Subjects.

Previously, it has been indicated that oat polar lipids included in a liquid meal may have the potential to beneficially modulate various cardiometabolic variables. The purpose of this study was to evaluate the effects of oat polar lipids in a solid food matrix on acute and second meal glucose tolerance, blood lipids, and concentrations of gut-derived hormones. The oat polar lipids were consumed at breakfast and effects on the biomarkers were investigated in the postprandial period and following a standardized lunch. Twenty young, healthy subjects consumed in total four different breakfast meals in a crossover study design. The breakfasts consisted of 1. White wheat bread (WWB) with an added 7.5 g of oat polar lipids (PLL); 2. WWB with an added 15 g of oat polar lipids (PLH); 3. WWB with and added 16.6 g of rapeseed oil (RSO) as a representative of commonly consumed oils; and 4. WWB consumed alone, included as a reference. All products with added lipids contained equivalent amounts of fat (16.6 g) and available carbohydrates (50 g). Rapeseed oil was added to the oat polar lipid meals to equal 16.6 g of total fat. The standardized lunch was composed of WWB and meatballs and was served 3.5 h after the breakfast. Test variables (blood glucose, serum insulin, triglyceride (TG), free fatty acids (FFA), ghrelin, GLP-1, PYY, and GIP) were measured at fasting and repeatedly during the 5.5 h after ingestion of the breakfast. After breakfast, PLH substantially lowered postprandial glucose and insulin responses (iAUC 0-120 min) compared with RSO and WWB (p < 0.05). Furthermore, a reduced glycaemic response to lunch (210-330 min) was observed following the PLH breakfast compared to all of the other breakfasts served (p < 0.05). Oat polar lipids (PLH) significantly reduced TG and ghrelin and increased circulating gut hormones GLP-1 and PYY compared to RSO (p < 0.05). The results show that exchanging part of the dietary lipids with oat polar lipids has the potential to improve postprandial blood glucose regulation and gut hormones and thus may have a preventive effect against type 2 diabetes.

RF04 | PSUN297 Genetic Knockout of Intestinal Hexokinase Domain Containing Protein-1 Affects Enterocyte Glucose Transport in Mice Fed High Fat Diet

Abstract Hexokinase domain containing protein-1, or HKDC1, is a widely expressed novel hexokinase that is genetically associated with elevated 2-hour gestational blood glucose levels during an oral glucose tolerance test, suggesting a role for HKDC1 in postprandial glucose regulation during pregnancy. Our earlier studies utilizing transgenic mice containing whole-body HKDC1 knockdown, or mice in which hepatic HKDC1 was overexpressed or knocked out, indicated that HKDC1 is important for whole-body glucose homeostasis in aging and pregnancy, through modulation of glucose tolerance, peripheral tissue glucose utilization, and hepatic energy storage. However, our knowledge of the precise mechanisms by which HKDC1 regulates postprandial glucose homeostasis under normal and diabetic conditions is lacking. As the intestine is the main entry portal for dietary glucose, and since HKDC1 is highly expressed within the intestine, in this study we assessed and characterized the in vivo significance of intestine-specific HKDC1 in regulating glucose homeostasis under normal and obesogenic conditions. We developed an intestine-specific HKDC1 knockout mouse model, HKDC1Int-/-, utilizing Cre-mediated recombination of HKDC1 in which Cre was expressed under the control of the villin gene promoter, leading to genetic knockout of HKDC1 solely within the intestinal epithelium. Mice were maintained until 28 weeks of age on either a normal chow diet or a high fat diet to develop obesity, hyperglycemia, and insulin resistance. While no overt glycemic phenotype was observed, 28-week-old HKDC1Int-/- mice fed a high fat diet exhibited an increased glucose excursion following an oral glucose load compared to mice expressing intestinal HKDC1. This finding was not due to differences in insulin levels, whole-body insulin tolerance, or gluconeogenesis, nor was it a result of alterations in enterocyte glucose utilization or a reduction in peripheral skeletal muscle glucose uptake. Furthermore, the enhanced glucose excursion was related to transport of glucose through the intestinal epithelium, as mice administered an intraperitoneal glucose load did not exhibit alterations in post-load glycemic excursion. Assessment of intestinal glucose transporters in high fat diet-fed HKDC1Int-/- mice indicated an increased expression of GLUT2 in the enterocyte apical membrane in the fasting state. Taken together, our results indicate that intestine-specific HKDC1 contributes to postprandial glycemic regulation by modulating dietary glucose transport across the intestinal epithelium under conditions of enhanced metabolic stress, such as obesity, hyperglycemia, and diabetes. Presentation: Saturday, June 11, 2022 1:24 p.m. - 1:29 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Near-optimal feedback control for postprandial glucose regulation in type 1 diabetes

This paper is focused on feedback control of postprandial glucose levels for patients with type 1 Diabetes Mellitus. There are two important limitations that make this a challenging problem. First, the slow subcutaneous insulin pharmacokinetics that introduces a significant lag into the control loop. Second, the positivity constraint on the control action, meaning that it is not possible to remove insulin from the body. In this paper, both issues are explicitly considered in the design process using the internal model control framework, to derive a near-optimal feedback controller. Optimality is understood here as minimizing the blood glucose peak after a meal intake and, at the same time, preventing glucose values below a prescribed threshold. It is shown how the proposed controller approaches the optimal closed-loop performance as a limit case. The theoretical results are supported by a numerical example and the feasibility of the overall strategy under uncertainties is illustrated using an extended version UVa/Padova metabolic simulator.

Thrice daily consumption of a novel, premeal shot containing a low dose of whey protein increases time in euglycemia during 7 days of free-living in individuals with type 2 diabetes

IntroductionDuring acute feeding trials, consuming a large dose of whey protein (WP) before meals improves postprandial glucose regulation in people with type 2 diabetes. It is unclear if the reported...

Enterocyte HKDC1 Modulates Intestinal Glucose Absorption in Male Mice Fed a High-fat Diet.

Hexokinase domain containing protein-1, or HKDC1, is a widely expressed hexokinase that is genetically associated with elevated 2-hour gestational blood glucose levels during an oral glucose tolerance test, suggesting a role for HKDC1 in postprandial glucose regulation during pregnancy. Our earlier studies utilizing mice containing global HKDC1 knockdown, as well as hepatic HKDC1 overexpression and knockout, indicated that HKDC1 is important for whole-body glucose homeostasis in aging and pregnancy, through modulation of glucose tolerance, peripheral tissue glucose utilization, and hepatic energy storage. However, our knowledge of the precise role(s) of HKDC1 in regulating postprandial glucose homeostasis under normal and diabetic conditions is lacking. Since the intestine is the main entry portal for dietary glucose, here we have developed an intestine-specific HKDC1 knockout mouse model, HKDC1Int–/–, to determine the in vivo role of intestinal HKDC1 in regulating glucose homeostasis. While no overt glycemic phenotype was observed, aged HKDC1Int–/– mice fed a high-fat diet exhibited an increased glucose excursion following an oral glucose load compared with mice expressing intestinal HKDC1. This finding resulted from glucose entry via the intestinal epithelium and is not due to differences in insulin levels, enterocyte glucose utilization, or reduction in peripheral skeletal muscle glucose uptake. Assessment of intestinal glucose transporters in high-fat diet–fed HKDC1Int–/– mice suggested increased apical GLUT2 expression in the fasting state. Taken together, our results indicate that intestinal HKDC1 contributes to the modulation of postprandial dietary glucose transport across the intestinal epithelium under conditions of enhanced metabolic stress, such as high-fat diet.

IDF21-0453 Phase-3 active control trial to evaluate Safety and Efficacy of Repaglinide plus Voglibose combination in T2D patients

Background: Post-prandial hyperglycemia (PPHG) appears to be the rate limiting factor for achieving optimal glycemic control in Type 2 diabetes (T2D). In DECODA study, 2 h postprandial plasma glucose (PPG) was found to be superior to fasting plasma glucose (FPG) in predicting premature CV mortality. Clinical use of Repaglinide and Voglibose combination in T2D offers post-prandial glucose regulation while modulating the first phase of insulin secretion that is often blunted in such cases.

Effects of Acute Resistance Exercise with and without Whole-Body Electromyostimulation and Endurance Exercise on the Postprandial Glucose Regulation in Patients with Type 2 Diabetes Mellitus: A Randomized Crossover Study.

Background: Long hyperglycemic episodes trigger complications in type 2 diabetes mellitus (T2DM) patients. Postprandial glucose excursions can be reduced by acute physical activity. However, it is not yet clear which type of exercise has the best effect on postprandial glucose levels. Methods: Six T2DM patients participated in three 20-min moderate-intensity exercise sessions after breakfast in a randomized order: resistance exercise with whole-body electromyostimulation (WB-EMS), resistance exercise without electromyostimulation (RES) and cycling endurance exercise (END). A continuous glucose monitoring system recorded glucose dynamics. Results: Postprandially-increased glucose levels decreased in all cases. Time to baseline (initial value prior to meal intake) was quite similar for WB-EMS, RES and END. Neither glucose area under the curve (AUC), nor time in range from the start of the experiment to its end (8 h later) differed significantly. A Friedman analysis of variance, however, revealed an overall significant difference for AUC in the post-exercise recovery phase (END seems to have superior effects, but post-hoc tests failed statistical significance). Conclusions: There are no notable differences between the effects of the different types of exercise on glucose levels, especially when comparing values over a longer period of time.

Bayesian optimization assisted meal bolus decision based on Gaussian processes learning and risk-sensitive control

Effective postprandial glucose control is important to glucose management for subjects with diabetes mellitus. In this work, a data-driven meal bolus decision method is proposed without the need of subject-specific glucose management parameters. The postprandial glucose dynamics is learnt using Gaussian process regression. Considering the asymmetric risks of hyper- and hypoglycemia and the uncertainties in the predicted glucose trajectories, an asymmetric risk-sensitive cost function is designed. Bayesian optimization is utilized to solve the optimization problem, since the gradient of the cost function is unavailable. The proposed approach is evaluated using the 10-adult cohort of the FDA-accepted UVA/Padova T1DM simulator and compared with the standard insulin bolus calculator. For the case of announced meals, the proposed method achieves satisfactory and similar performance in terms of mean glucose and percentage time in [70, 180] mg/dL without increasing the risk of hypoglycemia. Similar results are observed for the case without the meal information (assuming that the patient follows a consistent diet) and the case of basal rate mismatches. In addition, a comparison with a run-to-run based method for the scenario of potentially incorrect meal carbohydrate counts is also performed, and the results show that the proposed method is more robust to the carbohydrate counting disturbances. At last, advisory-mode analysis is performed based on clinical data, which indicates that the method can determine safe and reasonable meal boluses in real clinical settings. The results verify the effectiveness and robustness of the proposed method and indicate the feasibility of achieving improved postprandial glucose regulation through a data-driven optimal control method.

Investigation of the binding interaction of α-amylase with Chrysophyllum albidum seed extract and its silver nanoparticles: A multi-spectroscopic approach

• α-Amylase binding interactions with CSME and CSAgNP were studied. • UV-vis, FT-IR and fluorescence showed evidence of binding interactions. • Intrinsic fluorescence of α-amylase was quenched by static mechanism. • Microenvironments of α-amylase active site tyrosine residues were altered. • CSME and CSAgNP showed strong inhibition against α-amylase. The interactions between α-amylase, one of the key enzymes linked with postprandial glucose regulation, and Chrysophyllum albidum seed methanolic extract(CSME) and its green-synthesized silver nanoparticles(CSAgNP) were investigated using multiple spectroscopy including Fourier Transform-Infrared(FT-IR), ultraviolet(UV)-visible absorption, fluorescence spectroscopy, and biochemical analysis. FT-IR spectroscopy revealed presence of some functional groups in the samples. CSME and CSAgNP inhibited α-amylase. The intrinsic fluorescence intensity of α-amylase was quenched by CSME and CSAgNP via static mechanisms, indicating formation of complex between the enzyme and inhibitors. α-Amylase-CSAgNP complex had higher binding constants. The binding processes were exothermic, entropy driven, spontaneous, and involved hydrogen bonds and van der Waals force. Synchronous fluorescence quenching indicated alteration in microenvironment of α-amylase catalytic site tyrosine residues.FT-IR spectroscopy revealed shifts in amide I peak position of α-amylase due to interaction with CSME/CSAgNP. Absorption spectroscopy also affirmed changes in enzyme conformation. This study may provide theoretical basis for designing novel α-amylase inhibitors. The binding interactions of α-amylase with CSME and CSAgNP were investigated/ affirmed using multiple spectroscopic and biochemical methods following established protocols.

The effect of body acid-base state and manipulations on body glucose regulation in human.

Long-term exposure to high dietary acid load has been associated with insulin resistance and type 2 diabetes in epidemiological studies. However, it remains unclear whether the acid load of the diet translates to mild metabolic acidosis and whether it is responsible for the impairment in glucose regulation in humans. Previously, in a cross-sectional study we have reported that dietary acid load was not different between healthy individuals with normal weight and those with overweight/obesity, irrespective of insulin sensitivity. However, 4-week high acid load diet increased plasma lactate (a small component of the anion gap) and increased insulin resistance in healthy participants. The change in plasma lactate correlated significantly with the change in insulin resistance. Because cause-and-effect could not be evaluated in these settings, we sought to directly test the effect of an alkalizing treatment preload on postprandial glucose regulation. In a randomized placebo-controlled study with a crossover design, we administered sodium bicarbonate (NaHCO3, 1.68 g) prior to high acid load meal to healthy individuals. We found that while the bicarbonate preload attenuated the post meal decrease in pH observed with placebo, no effect on postprandial glucose regulation (glucose, insulin, and C-peptide) was observed. Following 3-month treatment of nondiabetic individuals with bicarbonate, others have reported no change in insulin resistance markers, consistent with our findings. Together, studies in human suggest that insulin resistance associated with longstanding obesogenic diet may be mediated by mild metabolic acidosis. However, buffering the Western diet with bicarbonate and increasing body pH does not change glucose homeostasis in nondiabetic individuals. Further studies are required to shed light on the role of body acid-base balance and glucose homeostasis in health and disease.

Visual food cues decrease blood glucose and glucoregulatory hormones following an oral glucose tolerance test in normal-weight and obese men

Previous experiments of our group have demonstrated that preprandial processing of food cues attenuates postprandial blood glucose excursions. Here we systematically re-evaluated the glucose-lowering effect of visual food cues by submitting 40 healthy fasted men (20 normal-weight men, mean age 24.8 ± 3.7 years, BMI 21.9 ± 0.3 kg/m2; 20 obese men, 26.8 ± 4.2 years, 34.3 ± 1.3 kg/m2) to an oral glucose tolerance test (OGTT) following exposure to pictures of high-calorie food items versus neutral items. OGTT-related changes in blood concentrations of glucose and relevant glucoregulatory hormones including GLP-1 were assessed and analyzed according to the oral minimal model. Independent of body weight, food-cue compared to neutral stimulus presentation reduced postprandial concentrations of glucose (p = 0.041), insulin (p = 0.026) and C-peptide (p = 0.007); accordingly, oral minimal model analyses yielded a food-cue induced decrease of dynamic-phase insulin secretion (p = 0.036). We also observed a trend towards lower GLP-1 levels directly after food cue stimulation in both body weight groups (p = 0.057), as well as a trend towards decreased heart rate (p = 0.093) and significantly decreased diastolic blood pressure (p = 0.019). While we did not detect indicators of an early rise in insulin levels in terms of a ‘cephalic phase insulin response’, our findings support the assumption that preprandial processing of food cues exerts marked effect on postprandial glucose regulation, with possible contributions of changes in GLP-1. The mechanisms linking food cue exposure and glucoregulatory improvements should be investigated in greater detail, to potentially open new treatment options for metabolic dysfunctions.