Publications by authors named "Timothy J McDonald"

Article Synopsis
  • Researchers are studying type 2 diabetes, which happens when there is too much sugar in the blood, to see how certain substances in the body, called metabolites, are connected to it.
  • They looked at 3,000 blood samples and analyzed 911 metabolites to find out how these substances relate to blood sugar levels.
  • They discovered several metabolites that are different in people with normal blood sugar, those with prediabetes, and those with type 2 diabetes, mainly focusing on specific amino acids and fats.
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We investigated whether characterization of full-length GAD (f-GADA) antibody (GADA) responses could identify early insulin requirement in adult-onset diabetes. In 179 f-GADA-positive participants diagnosed with type 2 diabetes, we assessed associations of truncated GADA (t-GADA) positivity, f-GADA IgG subclasses, and f-GADA affinity with early insulin requirement (<5 years), type 1 diabetes genetic risk score (T1D GRS), and C-peptide. t-GADA positivity was lower in f-GADA-positive without early insulin in comparison with f-GADA-positive type 2 diabetes requiring insulin within 5 years, and T1D (75% vs.

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Introduction: the utility of glycated haemoglobin (HbA1c) for the diagnosis and monitoring of diabetes in sub-Saharan Africa is uncertain due to limited data on the performance of the available HbA1c assay methods in this population, which has a high prevalence of haemoglobin variants. We aimed to compare the diagnostic accuracy of the major HbA1c methodologies (Boronate Affinity, Capillary Electrophoresis, High Performance Liquid Chromatography, Immunoassay) in an African population, and assess the impact of the common haemoglobin variant HbAS (sickle cell trait).

Methods: whole blood samples were obtained from 182 individuals living with type 2 diabetes in Uganda.

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Aims/hypothesis: Use of genetic risk scores (GRS) may help to distinguish between type 1 diabetes and type 2 diabetes, but less is known about whether GRS are associated with disease severity or progression after diagnosis. Therefore, we tested whether GRS are associated with residual beta cell function and glycaemic control in individuals with type 1 diabetes.

Methods: Immunochip arrays and TOPMed were used to genotype a cross-sectional cohort (n=479, age 41.

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Background: Clinical prediction models can help identify high-risk patients and facilitate timely interventions. However, developing such models for rare diseases presents challenges due to the scarcity of affected patients for developing and calibrating models. Methods that pool information from multiple sources can help with these challenges.

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Context: The role of glucagon-like peptide-1 (GLP-1) in type 2 diabetes (T2D) and obesity is not fully understood.

Objective: We investigate the association of cardiometabolic, diet, and lifestyle parameters on fasting and postprandial GLP-1 in people at risk of, or living with, T2D.

Methods: We analyzed cross-sectional data from the two Innovative Medicines Initiative (IMI) Diabetes Research on Patient Stratification (DIRECT) cohorts, cohort 1 (n = 2127) individuals at risk of diabetes; cohort 2 (n = 789) individuals with new-onset T2D.

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Aims/hypothesis: Our aim was to characterise the in-depth metabolic response to aerobic exercise and the impact of residual pancreatic beta cell function in type 1 diabetes. We also aimed to use the metabolome to distinguish individuals with type 1 diabetes with reduced maximal aerobic capacity in exercise defined by .

Methods: Thirty participants with type 1 diabetes (≥3 years duration) and 30 control participants were recruited.

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Article Synopsis
  • The study aimed to evaluate the effectiveness of two medications, infliximab and adalimumab, for treating patients with active Crohn's disease over three years and to identify what factors contribute to treatment failure.
  • It involved a large cohort of patients across the UK, tracking their responses to anti-TNF therapy and analyzing reasons for loss of effectiveness.
  • Findings showed that remission rates declined over time for both medications, with around 40% of patients on infliximab and about 35% on adalimumab remaining in remission by the end of Year 1, suggesting ongoing challenges in maintaining treatment effectiveness.
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Article Synopsis
  • Transdermal capillary blood (TCB) sampling was evaluated as a practical alternative to traditional venous blood sampling for measuring C-peptide and islet autoantibodies in individuals with type 1 diabetes.
  • In a study with 91 participants, TCB demonstrated high sensitivity and specificity in detecting levels of C-peptide compared to venous sampling, with very few sample failures.
  • Most participants preferred TCB sampling over venous sampling, indicating it could be a more acceptable method for monitoring diabetes biomarkers in clinical settings.
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Article Synopsis
  • The study examines genetic regulation of mRNA, proteins, and metabolites in blood samples from over 3,000 people, revealing that many genetic variants influence multiple molecular traits.* -
  • It finds that there's a strong genetic connection between gene expression and protein levels (66.6%), and shows broad connections across various tissues, highlighting the shared genetic basis for different traits.* -
  • By creating networks of known genetic variants, the research indicates that these variants are more frequently linked to gene expression rather than other molecular traits, helping to clarify the mechanisms behind genetic associations.*
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The incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP), are thought to be the main drivers of insulin secretion in individuals with sulfonylurea (SU)-treated KCNJ11 permanent neonatal diabetes. The aim of this study was to assess for the first time the incretin hormone response to carbohydrate and protein/fat in adults with sulfonylurea-treated KCNJ11 permanent neonatal diabetes compared with that of controls without diabetes. Participants were given a breakfast high in carbohydrate and an isocaloric breakfast high in protein/fat on two different mornings.

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Objective: Little is known about the influence of residual islet function on glycemic control in type 1 diabetes (T1D). We investigated the associations between residual β-cell function and metrics of continuous glucose monitoring (CGM) in individuals with T1D.

Research Design And Methods: In this cross-sectional cohort comprising 489 individuals (64% female, age 41.

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Article Synopsis
  • Vitamin D plays a crucial role in immune function, and past research suggested its low levels might lead to ineffective treatment with anti-TNF therapies in Crohn's disease patients.
  • This study measured vitamin D levels in over 1,100 patients undergoing treatment with infliximab and adalimumab to assess if these levels could predict treatment outcomes.
  • The findings showed that while vitamin D deficiency is prevalent among these patients, it did not significantly predict non-response or non-remission to anti-TNF therapy within 14 weeks or 54 weeks, contrasting earlier studies' results.
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Objective: To determine whether presentation, progression, and genetic susceptibility of robustly defined adult-onset type 1 diabetes (T1D) are altered by diagnosis age.

Research Design And Methods: We compared the relationship between diagnosis age and presentation, C-peptide loss (annual change in urine C-peptide-creatinine ratio [UCPCR]), and genetic susceptibility (T1D genetic risk score [GRS]) in adults with confirmed T1D in the prospective StartRight study, 1,798 adults with new-onset diabetes. T1D was defined in two ways: two or more positive islet autoantibodies (of GAD antibody, IA-2 antigen, and ZnT8 autoantibody) irrespective of clinical diagnosis (n = 385) or one positive islet autoantibody and a clinical diagnosis of T1D (n = 180).

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The phenotype of type 1 diabetes in Africa, especially sub-Saharan Africa, is poorly understood. Most previously conducted studies have suggested that type 1 diabetes may have a different phenotype from the classical form of the disease described in western literature. Making an accurate diagnosis of type 1 diabetes in Africa is challenging, given the predominance of atypical diabetes forms and limited resources.

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Background: In the treatment of type 2 diabetes, GLP-1 receptor agonists lower blood glucose concentrations, body weight, and have cardiovascular benefits. The efficacy and side effects of GLP-1 receptor agonists vary between people. Human pharmacogenomic studies of this inter-individual variation can provide both biological insight into drug action and provide biomarkers to inform clinical decision making.

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Background: Anti-TNF drugs, such as infliximab, are associated with attenuated antibody responses after SARS-CoV-2 vaccination. We aimed to determine how the anti-TNF drug infliximab and the anti-integrin drug vedolizumab affect vaccine-induced neutralising antibodies against highly transmissible omicron (B.1.

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Objective: Recent joint American Diabetes Association and European Association for the Study of Diabetes guidelines recommend routine islet autoantibody testing in all adults newly diagnosed with type 1 diabetes. We aimed to assess the impact of routine islet autoantibody testing in this population.

Research Design And Methods: We prospectively assessed the relationship between islet autoantibody status (GADA, IA-2A, and ZNT8A), clinical and genetic characteristics, and progression (annual change in urine C-peptide-to-creatinine ratio [UCPCR]) in 722 adults (≥18 years old at diagnosis) with clinically diagnosed type 1 diabetes and diabetes duration <12 months.

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Context: The importance of the autoantibody level at diagnosis of type 1 diabetes (T1D) is not clear.

Objective: We aimed to assess the association of glutamate decarboxylase (GADA), islet antigen-2 (IA-2A), and zinc transporter 8 (ZnT8A) autoantibody levels with clinical and genetic characteristics at diagnosis of T1D.

Methods: We conducted a prospective, cross-sectional study.

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Article Synopsis
  • Anti-drug antibodies linked to treatment failure in inflammatory bowel disease (IBD) patients on anti-TNF agents were analyzed in a large UK study involving 1058 participants.
  • The study found that patients who developed antibodies to their first anti-TNF drug were more likely to also develop antibodies to their second anti-TNF drug, indicating a potential pattern of immunogenicity across different treatments.
  • Introducing an immunomodulator when switching anti-TNF therapies boosted treatment persistence in patients with immunogenicity, suggesting that combined therapies may enhance outcomes in IBD management.
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Objective: Antitumour necrosis factor (TNF) drugs impair serological responses following SARS-CoV-2 vaccination. We sought to assess if a third dose of a messenger RNA (mRNA)-based vaccine substantially boosted anti-SARS-CoV-2 antibody responses and protective immunity in infliximab-treated patients with IBD.

Design: Third dose vaccine induced anti-SARS-CoV-2 spike (anti-S) receptor-binding domain (RBD) antibody responses, breakthrough SARS-CoV-2 infection, reinfection and persistent oropharyngeal carriage in patients with IBD treated with infliximab were compared with a reference cohort treated with vedolizumab from the impaCt of bioLogic therApy on saRs-cov-2 Infection and immuniTY (CLARITY) IBD study.

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Article Synopsis
  • The study investigates the relationship between the serum free triiodothyronine-to-thyroxine (fT3/fT4) ratio and treatment effectiveness in Crohn's disease patients receiving infliximab or adalimumab.
  • It found that a lower fT3/fT4 ratio is linked to female sex, corticosteroid use, and more severe disease, and it can predict primary non-response (PNR) to treatment at week 14.
  • However, the fT3/fT4 ratio was not associated with non-remission outcomes at week 54, suggesting its predictive value is limited to early treatment responses.
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Anti tumour necrosis factor (anti-TNF) drugs increase the risk of serious respiratory infection and impair protective immunity following pneumococcal and influenza vaccination. Here we report SARS-CoV-2 vaccine-induced immune responses and breakthrough infections in patients with inflammatory bowel disease, who are treated either with the anti-TNF antibody, infliximab, or with vedolizumab targeting a gut-specific anti-integrin that does not impair systemic immunity. Geometric mean [SD] anti-S RBD antibody concentrations are lower and half-lives shorter in patients treated with infliximab than vedolizumab, following two doses of BNT162b2 (566.

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