Modeling the oral glucose tolerance test in normal and impaired glucose tolerant states: a population approach

<p><b>Objective:</b> The conventional approach to analyzing data from oral glucose tolerance testing (OGTT) requires model identification in each individual separately (standard two stage, STS), ignoring knowledge about the population as a whole. In practice, however, the OGTT is sparsely sampled and individual estimates are often not resolvable from available data. This weakness is often encountered in large scale trials or epidemiological studies, leading to either multiple imputations or simply much less data available for analysis.</p> <p><b>Methods:</b> We have applied a population approach, nonlinear mixed effects modeling, to plasma glucose, insulin and C-peptide data obtained from a 120 minute OGTT undertaken by 106 subjects with varying glucose tolerance. This method provides estimates of population means, variances and covariances of model parameters and empirical Bayes estimates of individual parameter values, as well as measures of intra-individual (within-subject) and inter-individual (between-subject) variability. The recently developed oral glucose minimal model was used to evaluate insulin sensitivity, and a combined model approach was used to assess β-cell secretion.</p> <p><b>Results:</b> Applying these models allowed for the reconstruction of insulin secretion and glucose absorption profiles and gave population indexes of insulin sensitivity (<i>S_I</i> = 6.51 ± 1.20 × 10⁻⁴ min⁻¹·μU⁻¹·ml), fractional hepatic extraction of insulin (<i>F</i> = 0.522 ± 0.291) and fractional insulin clearance (<i>k_I</i> = 0.258 ± 0.151 min⁻¹). Whereas the traditional approach to parameter estimation failed to recover estimates in more than one third of the population, the population approach provided individual estimates in all subjects. Examination of the empirical Bayes estimates showed that individual parameter estimates were able to differentiate well between individuals at glucose tolerant states ranging from euglycemia to overt type 2 diabetes.</p> <p><b>Conclusions:</b> Our findings suggest that population analysis is a powerful tool for obtaining accurate assessments of indexes of insulin sensitivity and β-cell function from the OGTT, especially in epidemiological studies with large numbers of sparsely sampled subjects.</p

Additional file 2: Table S2. of Dietary patterns, plasma vitamins and Trans fatty acids are associated with peripheral artery disease

Age, Gender, and Race Adjusted Mean of Nutrient Intakes Across Quartiles of Each Dietary Pattern. (DOCX 22 kb

Additional file 1: Table S1. of Dietary patterns, plasma vitamins and Trans fatty acids are associated with peripheral artery disease

Demographic, anthropometric and clinical characteristics of participants. (DOCX 13 kb

Data_Sheet_1_Effect of the Mediterranean diet and probiotic supplementation in the management of mild cognitive impairment: Rationale, methods, and baseline characteristics.docx

IntroductionMild cognitive impairment (MCI) can progress to Alzheimer’s disease (AD). When MCI is not properly controlled, the speed of deterioration can dramatically increase. Reduction of oxidative stress/inflammation and the modulation of the gut-brain axis could be new potential therapeutic targets for the prevention and treatment of AD. Consumption of specific nutrients, diets and probiotic supplementation have been evaluated for neurodegenerative disorders. We focus on a detailed description of the study methods and baseline characteristics of a clinical trial aiming to evaluate the efficacy of a combined nutritional intervention, i.e., a Mediterranean diet with probiotics, on cognitive capacity in a population with MCI.MethodsIn this randomized, latin-square crossover, double-blind, and controlled dietary intervention trial (clinicaltrials.gov NCT05029765), 47 MCI patients were randomized to consume three dietary interventions for 24-weeks each: (1) A Mediterranean diet supplemented with probiotics (109 colony-forming units of Lactobacillus rhamnosus and Bifidobacterium longum); (2) A Mediterranean diet + placebo; and (3) A Healthy diet according to the World Health Organization (WHO) recommendations. Participants will be evaluated before and after each of the three intervention periods (each 24-weeks, with a total of 72-weeks) for adherence to the assigned diet, blood tests, cognitive performance, gut microbiota analysis and functional neuroimaging studies.ResultsFifty patients, ≥60 years-old and diagnosed with MCI, underwent randomization. A total of 47 patients completed follow-up dietary interventions (57.4% males), with a good glycemic control (HbA1c 5.8 ± 0.1%, fasting glucose and insulin 99.7 ± 3.3 mg/dL and 10.4 ± 0.9 mU/L, respectively), elevated systolic blood pressure (136.9 ± 2.1 mmHg) and increased degree of inflammation (high-sensitivity C-reactive protein, 8.8 ± 0.9 mg/dL). Baseline adherence to the Mediterranean diet was medium (7.5 ± 0.3 points on the score that ranged from 0 to 14 points).ConclusionThe results of this clinical study would provide more evidence on the need for dietary therapeutic strategies, for clinical and individual practice, in the management of MCI patients to reduce the risk of AD development. Targeting lifestyle modifications in high-risk populations could prevent substantial cases of cognitive decline.Clinical trial registration[ClinicalTrials.gov], identifier [NCT05029765].</p