Impact of Nutrient Type and Sequence on Glucose Tolerance: Physiological Insights and Therapeutic Implications

Pharmacological and dietary interventions targeting postprandial glycemia have proved effective in reducing the risk for type 2 diabetes and its cardiovascular complications. Besides meal composition and size, the timing of macronutrient consumption during a meal has been recently recognized as a key regulator of postprandial glycemia. Emerging evidence suggests that premeal consumption of non-carbohydrate macronutrients (i.e., protein and fat “preloads”) can markedly reduce postprandial glycemia by delaying gastric emptying, enhancing glucose-stimulated insulin release, and decreasing insulin clearance. The same improvement in glucose tolerance is achievable by optimal timing of carbohydrate ingestion during a meal (i.e., carbohydrate-last meal patterns), which minimizes the risk of body weight gain when compared with nutrient preloads. The magnitude of the glucose-lowering effect of preload-based nutritional strategies is greater in type 2 diabetes than healthy subjects, being comparable and additive to current glucose-lowering drugs, and appears sustained over time. This dietary approach has also shown promising results in pathological conditions characterized by postprandial hyperglycemia in which available pharmacological options are limited or not cost-effective, such as type 1 diabetes, gestational diabetes, and impaired glucose tolerance. Therefore, preload-based nutritional strategies, either alone or in combination with pharmacological treatments, may offer a simple, effective, safe, and inexpensive tool for the prevention and management of postprandial hyperglycemia. Here, we survey these novel physiological insights and their therapeutic implications for patients with diabetes mellitus and altered glucose tolerance

Abnormal Glucose Tolerance Is Associated with a Reduced Myocardial Metabolic Flexibility in Patients with Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is characterized by a metabolic shift from fat to carbohydrates and failure to increase myocardial glucose uptake in response to workload increments. We verified whether this pattern is influenced by an abnormal glucose tolerance (AGT). In 10 patients with DCM, 5 with normal glucose tolerance (DCM-NGT) and 5 with AGT (DCM-AGT), and 5 non-DCM subjects with AGT (N-AGT), we measured coronary blood flow and arteriovenous differences of oxygen and metabolites during Rest, Pacing (at 130 b/min), and Recovery. Myocardial lactate exchange and oleate oxidation were also measured. At Rest, DCM patients showed a reduced nonesterified fatty acids (NEFA) myocardial uptake, while glucose utilization increased only in DCM-AGT. In response to Pacing, glucose uptake promptly rose in N-AGT (from 72 ± 21 to 234 ± 73 nmol/min/g, p<0.05), did not change in DCM-AGT, and slowly increased in DCM-NGT. DCM-AGT sustained the extra workload by increasing NEFA oxidation (from 1.3 ± 0.2 to 2.9 ± 0.1 mol/min/gO2 equivalents, p<0.05), while DCM-NGT showed a delayed increase in glucose uptake. Substrate oxidation rates paralleled the metabolites data. The presence of AGT in patients with DCM exacerbates both the shift from fat to carbohydrates in resting myocardial metabolism and the reduced myocardial metabolic flexibility in response to an increased workload. This trial is registered with ClinicalTrial.gov NCT02440217

Evaluation of the Incidence and Potential Mechanisms of Tracheal Complications in Patients With COVID-19

Full-thickness tracheal lesions and tracheoesophageal fistulas are severe complications of invasive mechanical ventilation. The incidence of tracheal complications in ventilated patients with coronavirus disease 2019 (COVID-19) is unknown

Incidence and types of laryngotracheal sequelae of prolonged invasive ventilation in COVID-19 patients

Purpose The COVID-19 outbreak has led to an increasing number of acute laryngotracheal complications in patients subjected to prolonged mechanical ventilation, but their incidence in the short and mid-term after ICU discharge is still unknown. The main objective of this study is to evaluate the incidence of these complications in a COVID-19 group of patients and to compare these aspects with non-COVID-19 matched controls. Methods In this cohort study, we retrospectively selected patients from November 1 to December 31, 2020, according to specific inclusion and exclusion criteria. The follow-up visits were planned after 6 months from discharge. All patients were subjected to an endoscopic evaluation and completed two questionnaires (VHI-10 score and MDADI score). Results Thirteen men and three women were enrolled in the COVID-19 group while nine men and seven women were included in the control group. The median age was 60 [56-66] years in the COVID-19 group and 64 [58-69] years in the control group. All the patients of the control group showed no laryngotracheal lesions, while five COVID-19 patients had different types of lesions, two located in the vocal folds and three in the trachea. No difference was identified between the two groups regarding the VHI-10 score, while the control group showed a significantly worse MDADI score. Conclusions COVID-19 patients subjected to prolonged invasive ventilation are more likely to develop a laryngotracheal complication in the short and medium term. A rigorous clinical follow-up to allow early identification and management of these complications should be set up after discharge

Early time-restricted carbohydrate consumption vs conventional dieting in type 2 diabetes: a randomised controlled trial

AIMS/HYPOTHESIS Early time-restricted carbohydrate consumption (eTRC) is a novel dietary strategy that involves restricting carbohydrate-rich food intake to the morning and early afternoon to align with circadian variations in glucose tolerance. We examined the efficacy, feasibility and safety of eTRC in individuals with type 2 diabetes under free-living conditions. METHODS In this randomised, parallel-arm, open label, controlled trial, participants with type 2 diabetes and overweight/obesity (age 67.2±7.9 years, 47.8% women, BMI 29.4±3.7 kg/m$^{2}$, HbA$_{1c}$ 49±5 mmol/mol [6.6±0.5%]) were randomised, using computer-generated random numbers, to a 12 week eTRC diet or a Mediterranean-style control diet with matched energy restriction and macronutrient distribution (50% carbohydrate, 30% fat and 20% protein). The primary outcome was the between-group difference in HbA$_{1c}$ at 12 weeks. Body composition, 14 day flash glucose monitoring and food diary analysis were performed every 4 weeks. Mixed meal tolerance tests with mathematical beta cell function modelling were performed at baseline and after 12 weeks. RESULTS Twelve (85.7%) participants in the eTRC arm and 11 (84.6%) participants in the control arm completed the study, achieving similar reductions in body weight and fat mass. The two groups experienced comparable improvements in HbA$_{1c}$ (-3 [-6, -0.3] mmol/mol vs -4 [-6, -2] mmol/mol, corresponding to -0.2 [-0.5, 0]% and -0.3 [-0.5, -0.1]%, respectively, p=0.386), fasting plasma glucose, flash glucose monitoring-derived glucose variability and mixed meal tolerance test-derived glucose tolerance, insulin resistance, insulin clearance and plasma glucagon levels, without changes in model-derived beta cell function parameters, glucagon-like peptide-1, glucose-dependent insulinotropic polypeptide and non-esterified fatty acid levels. The two diets similarly reduced liver function markers and triglyceride levels, being neutral on other cardiometabolic and safety variables. In exploratory analyses, diet-induced changes in body weight and glucometabolic variables were not related to the timing of carbohydrate intake. CONCLUSIONS/INTERPRETATION The proposed eTRC diet provides a feasible and effective alternative option for glucose and body weight management in individuals with type 2 diabetes, with no additional metabolic benefits compared with conventional dieting. TRIAL REGISTRATION ClinicalTrials.gov NCT05713058 FUNDING: This study was supported by the European Society for Clinical Nutrition and Metabolism (ESPEN) and the Italian Society of Diabetology (SID)

Disruption of fasting and post-load glucose homeostasis are largely independent and sustained by distinct and early major beta-cell function defects: a cross-sectional and longitudinal analysis of the relationship between insulin sensitivity and cardiovascular risk (RISC) study cohort

Background/aims: Uncertainty still exists on the earliest beta-cell defects at the bases of the type 2 diabetes. We assume that this depends on the inaccurate distinction between fasting and post-load glucose homeostasis and aim at providing a description of major beta-cell functions across the full physiologic spectrum of each condition. Methods: In 1320 non-diabetic individuals we performed an OGTT with insulin secretion modeling and a euglycemic insulin clamp, coupled in subgroups to glucose tracers and IVGTT; 1038 subjects underwent another OGTT after 3.5 years. Post-load glucose homeostasis was defined as mean plasma glucose above fasting levels (δOGTT). The analysis was performed by two-way ANCOVA. Results: Fasting plasma glucose (FPG) and δOGTT were weakly related variables (stβ = 0.12) as were their changes over time (r = −0.08). Disruption of FPG control was associated with an isolated and progressive decline (approaching 60%) of the sensitivity of the beta-cell to glucose values within the normal fasting range. Disruption of post-load glucose control was characterized by a progressive decline (approaching 60%) of the slope of the full beta-cell vs glucose dose-response curve and an early minor (30%) decline of potentiation. The acute dynamic beta-cell responses, neither per se nor in relation to the degree of insulin resistance appeared to play a relevant role in disruption of fasting or post-load homeostasis. Follow-up data qualitatively and quantitatively confirmed the results of the cross-sectional analysis. Conclusion: In normal subjects fasting and post-load glucose homeostasis are largely independent, and their disruption is sustained by different and specific beta-cell defects

Clinical Features, Cardiovascular Risk Profile, and Therapeutic Trajectories of Patients with Type 2 Diabetes Candidate for Oral Semaglutide Therapy in the Italian Specialist Care

Introduction: This study aimed to address therapeutic inertia in the management of type 2 diabetes (T2D) by investigating the potential of early treatment with oral semaglutide. Methods: A cross-sectional survey was conducted between October 2021 and April 2022 among specialists treating individuals with T2D. A scientific committee designed a data collection form covering demographics, cardiovascular risk, glucose control metrics, ongoing therapies, and physician judgments on treatment appropriateness. Participants completed anonymous patient questionnaires reflecting routine clinical encounters. The preferred therapeutic regimen for each patient was also identified. Results: The analysis was conducted on 4449 patients initiating oral semaglutide. The population had a relatively short disease duration (42%  60% of patients, and more often than sitagliptin or empagliflozin. Conclusion: The study supports the potential of early implementation of oral semaglutide as a strategy to overcome therapeutic inertia and enhance T2D management