The role of autoimmunity in the pathophysiology of type 2 diabetes: Looking at the other side of the moon

Insulin Resistance in Type 1 Diabetes: Pathophysiological, Clinical, and Therapeutic Relevance

People with type 1 diabetes (T1D) are usually considered to exclusively exhibit β-cell failure, but they frequently also feature insulin resistance. This review discusses the mechanisms, clinical features, and therapeutic relevance of insulin resistance by focusing mainly on human studies using gold-standard techniques (euglycemic-hyperinsulinemic clamp). In T1D, tissue-specific insulin resistance can develop early and sustain throughout disease progression. The underlying pathophysiology is complex, involving both metabolic- and autoimmune-related factors operating synergistically. Insulin treatment may play an important pathogenic role in predisposing individuals with T1D to insulin resistance. However, the established lifestyle-related risk factors and peripheral insulin administration inducing glucolipotoxicity, hyperinsulinemia, hyperglucagonemia, inflammation, mitochondrial abnormalities, and oxidative stress cannot always fully explain insulin resistance in T1D, suggesting a phenotype distinct from type 2 diabetes. The mutual interaction between insulin resistance and impaired endothelial function further contributes to diabetes-related complications. Insulin resistance should therefore be considered a treatment target in T1D. Aside from lifestyle modifications, continuous subcutaneous insulin infusion can ameliorate insulin resistance and hyperinsulinemia, thereby improving glucose toxicity compared with multiple injection insulin treatment. Among other concepts, metformin, pioglitazone, incretin-based drugs such as GLP-1 receptor agonists, sodium-glucose cotransporter inhibitors, and pramlintide can improve insulin resistance, either directly or indirectly. However, considering the current issues of high cost, side effects, limited efficacy, and their off-label status, these agents in people with T1D are not widely used in routine clinical care at present.

Exploring causal correlations between immune cells and diabetic neuropathy: a Mendelian randomization

BACKGROUND

Circulating immune cells reportedly affect diabetic neuropathy (DN). Although associations have been previously established between numerous biomarkers and diseases, elucidating their causal relationships remains challenging. Mendelian Randomization (MR) could overcome this difficulty by applying genetic instruments to discern causal links. In this study, we conducted bidirectional two-sample MR to address this problem.

METHODS

We used freely available genome-wide association study summary statistics. We obtained immune cell phenotype-related summary data from a study cohort comprising 3,757 Sardinian individuals that reported data concerning 731 immune cell phenotypes. We obtained DN-related summary data from the FinnGen database and conducted sensitivity analyses. Furthermore, we assessed horizontal pleiotropy using combined MR-Egger and MR-Presso methods. We evaluated heterogeneity using Cochran's Q test and applied False Discovery Rate correction to the findings.

RESULTS

Our MR analysis significantly associated 24 immune cell phenotypes with DN. Specifically, the presence of CD45 on CD66b + + myeloid cells, HLA DR on CD14 + CD16- monocytes, IgD- CD24- %B cells, and CD27 on IgD- CD38br lymphocytes significantly positively correlated with the risk of DN. In contrast, the presence of CD28- DN (CD4-CD8-) %T cells, FSC-A on HLA DR + T cells, and other four T cell types negatively correlated with DN. Finally, we further confirmed the relationship between different immune cell types and DN.

CONCLUSIONS

We demonstrated the immunological susceptibility of DN and clarified how immune responses influence the course of DN. These findings might help inform immunological therapy techniques as well as novel targets for DN diagnosis and treatment.

Pentraxin-3 as a Biomarker in Diabetes Mellitus: Insights into Inflammation, Vascular Complications, and Modulation by Antidiabetic Medications

Diabetes mellitus (DM) is a multifactorial metabolic disorder associated with systemic inflammation and vascular complications. Pentraxin-3 (PTX3) has emerged as a key biomarker of inflammation and endothelial dysfunction in DM. We aimed to examine the role of PTX3 in DM and assesses the impact of pharmacological interventions on its expression. The review included studies analyzing PTX3 modulation by antidiabetic therapies, such as sodium-glucose cotransporter-2 inhibitors (SGLT-2i), glucagon-like peptide-1 agonists (GLP-1a), and dipeptidyl peptidase-4 inhibitors (DPP-4i), as well as the effects of lifestyle interventions. Clinical and experimental studies demonstrated a strong correlation between PTX3 levels and DM progression. Elevated PTX3 levels were associated with diabetic complications, including nephropathy, retinopathy, and cardiovascular diseases. Antidiabetic drugs showed differential effects on PTX3 expression, with GLP-1a and DPP-4i significantly reducing PTX3 levels, while SGLT-2i displayed a paradoxical increase. Lifestyle interventions, including dietary modifications and weight loss, yielded inconsistent effects, suggesting genetic and metabolic factors influence PTX3 regulation. While pharmacological therapies, particularly GLP-1a and DPP-4i, demonstrate anti-inflammatory effects, further research is needed to standardize PTX3 measurement and explore its potential as a therapeutic target. Personalized treatment strategies incorporating genetic profiling may optimize inflammation control and disease management in DM patients.

Presepsin: An Emerging Biomarker in the Management of Cardiometabolic Disorders

Background/Objectives: Systemic and tissue inflammation play a crucial role in the pathophysiology of cardiometabolic disorders. Presepsin is a newly discovered marker of acute phase inflammation that is produced by monocytes or macrophages in response to bacterial infection and is a soluble fraction of the lipopolysaccharide (LPS) receptor. LPS is an endotoxin that, through the breakdown of the intestinal barrier, penetrates the systemic circulation and is an important bacterial mediator in the pathogenesis of sepsis and septic shock. Methods: A narrative review of the existing literature. Results: A growing body of evidence demonstrates that intestinal dysbiosis is involved in the pathogenesis of diabetes mellitus (DM) and cardiovascular (CV) disease, leading to increased circulating LPS concentrations in people with cardiometabolic disorders, even in the absence of infection. These data provide the theoretical background for a link between presepsin, DM, and CV pathology. Preliminary studies suggest that presepsin levels are downregulated in patients with well-controlled type 2 DM and correlate with continuous glucose monitoring metrics in infection-free individuals with type 1 DM. However, prospective data on the association between presepsin and the risk of diabetic complications are currently lacking. Presepsin has also been found to be elevated in infection-free individuals with myocardial infarction, heart failure, and myocarditis compared to controls and has been shown to correlate with mortality risk in subjects at high CV risk. Conclusions: The clinical utility of presepsin in the monitoring of patients with cardiometabolic disorders warrants further investigation by future studies.

Obesity, but Not Overweight, Is Associated with Increased Presepsin Levels in Infection-Free Individuals: An Exploratory Study

Background/Objectives: Intestinal dysbiosis and systemic inflammation are involved in the pathophysiology of obesity and its complications. Presepsin is a recently discovered inflammation marker, being the soluble form of the bacterial lipopolysaccharide (LPS) receptor. Due to the imbalance of the gut flora and subsequent disruption of the intestinal barrier, circulating LPS levels have been found to be elevated in patients with metabolic diseases, even in the absence of infection. However, to date, no studies have evaluated whether obesity is associated with elevated presepsin levels. Methods: The present study included 81 participants (61.7% women, 27 with obesity, 34 with overweight, and 20 controls with normal body mass index), all free of infection and diabetes mellitus. Presepsin was measured in serum by ELISA, and its concentrations were compared between the groups. Results: The obesity group had higher presepsin levels compared to controls (8.09 vs. 4.45 ng/mL, p = 0.06). When participants with a history of cardiovascular disease were excluded from the analysis and adjusting for multiple confounders through a regression model, the obesity group had higher presepsin values than the overweight and control groups (5.84 vs. 3.32 ng/mL, p = 0.016). In contrast, the overweight group had lower concentrations than both the obesity group (p = 0.005) and the controls (p = 0.031). We did not find an association between presepsin and 25-hydroxy vitamin D levels (p = 0.368). Conclusions: Although the cross-sectional character of the study cannot demonstrate causal relationships, the results could potentially suggest that systemic inflammation is implicated in the pathogenesis of obesity through the disruption of the intestinal barrier. However, the findings should only be seen as hypothesis-generating. The reduction in presepsin in the overweight state is an interesting finding that deserves further investigation.

SARS-CoV-2 Infection and New-Onset Type 2 Diabetes Among Pediatric Patients, 2020 to 2022

Importance

In adults, diagnoses of new-onset type 2 diabetes (T2D) have increased following diagnosis with COVID-19, but whether this occurs in children is unclear.

Objective

To determine whether risk of incident T2D diagnosis is increased during the 6 months after SARS-CoV-2 infection among children.

Design, Setting, and Participants

This retrospective cohort study used electronic health records from the TriNetX analytics platforms between January 1, 2020, and December 31, 2022. Pediatric patients aged 10 to 19 years without preexisting diabetes were eligible for inclusion. Data were analyzed from August 15 to September 15, 2023, with supplemental analyses January 20 and August 8 to 13, 2024.

Exposures

Diagnosis of COVID-19 or a non-COVID-19 respiratory infection.

Main Outcomes and Measures

New diagnosis of T2D compared by risk ratios (RRs) and 95% CIs at 1, 3, and 6 months after index infection.

Results

The main study population included 613 602 patients, consisting of 306 801 with COVID-19 (mean [SD] age at index, 14.9 [2.9] years; 52.8% female) and 306 801 with other respiratory infections (ORIs) but no documented COVID-19 (mean [SD] age at index, 14.9 [2.9] years; 52.6% female) after propensity score matching. Risk of a new diagnosis of T2D was significantly increased from day of infection to 1, 3, and 6 months after COVID-19 diagnosis compared with the matched cohort with ORIs (RR at 1 month, 1.55 [95% CI, 1.28-1.89]; RR at 3 months: 1.48 [95% CI, 1.24-1.76]; RR at 6 months: 1.58 [95% CI, 1.35-1.85]). Similar results were found in the subpopulation classified as having overweight or obesity (RR at 1 month: 2.07 [95% CI, 1.12-3.83]; RR at 3 months: 2.00 [95% CI, 1.15-3.47]; RR at 6 months: 2.27 [95% CI, 1.38-3.75]) and the hospitalized subpopulation (RR at 1 month: 3.10 [95% CI, 2.04-4.71]; RR at 3 months: 2.74 [95% CI, 1.90-3.96]; RR at 6 months: 2.62 [95% CI, 1.87-3.66]). Similar elevation in risk was found at 3 and 6 months when excluding patients diagnosed during the interval from the index date to 1 month after infection.

Conclusions and Relevance

In this retrospective cohort study of children and adolescents aged 10 to 19 years, the risk of an incident diagnosis of T2D was greater following a COVID-19 diagnosis than in children diagnosed with ORIs. Further study is required to determine whether diabetes persists or reverses later in life.

Genome-wide cross-disease analyses highlight causality and shared biological pathways of type 2 diabetes with gastrointestinal disorders

Studies suggest links between diabetes and gastrointestinal (GI) traits; however, their underlying biological mechanisms remain unclear. Here, we comprehensively assess the genetic relationship between type 2 diabetes (T2D) and GI disorders. Our study demonstrates a significant positive global genetic correlation of T2D with peptic ulcer disease (PUD), irritable bowel syndrome (IBS), gastritis-duodenitis, gastroesophageal reflux disease (GERD), and diverticular disease, but not inflammatory bowel disease (IBD). We identify several positive local genetic correlations (negative for T2D - IBD) contributing to T2D's relationship with GI disorders. Univariable and multivariable Mendelian randomisation analyses suggest causal effects of T2D on PUD and gastritis-duodenitis and bidirectionally with GERD. Gene-based analyses reveal a gene-level genetic overlap between T2D and GI disorders and identify several shared genes reaching genome-wide significance. Pathway-based study implicates leptin (T2D - IBD), thyroid, interferon, and notch signalling (T2D - IBS), abnormal circulating calcium (T2D - PUD), cardiovascular, viral, proinflammatory and (auto)immune-mediated mechanisms in T2D and GI disorders. These findings support a risk-increasing genetic overlap between T2D and GI disorders (except IBD), implicate shared biological pathways with putative causality for certain T2D - GI pairs, and identify targets for further investigation.

Drawing lines in the sand: The growing threat of obesity in type 1 diabetes

In this editorial, we comment on the article by Zeng et al published in the recent issue of the World Journal of Diabetes in 2024. We focus on the epidemiological, pathophysiological, and clinical interplay between obesity and type 1 diabetes mellitus (T1DM). Overweight and obesity represent a growing threat for modern societies and people with T1DM could not be an exception to this rule. Chronic exogenous insulin administration, genetic and epigenetic factors, and psy-chosocial and behavioral parameters, along with the modern way of life that incorporates unhealthy eating patterns and physical inactivity, set the stage for the increasing obesity rates in T1DM. As our knowledge of the underlying mechanisms that lead to the development of obesity and hyperglycemia expands, it becomes clear that there are overlap zones in the pathophysiology of the two main types of diabetes. Stereotypes regarding strict dividing lines between "autoimmune" and "metabolic" phenotypes increase the risk of trapping physicians into ineffective therapeutic approaches, instead of individualized diabetes care. In this context, the use of adjuncts to insulin therapy that have the potential to alleviate cardiorenal risk and decrease body weight can reduce the burden of obesity in patients with T1DM.

GAD65Abs Are Not Associated With Beta-Cell Dysfunction in Patients With T2D in the GRADE Study

Context

Autoantibodies directed against the 65-kilodalton isoform of glutamic acid decarboxylase (GAD65Abs) are markers of autoimmune type 1 diabetes (T1D) but are also present in patients with Latent Autoimmune Diabetes of Adults and autoimmune neuromuscular diseases, and also in healthy individuals. Phenotypic differences between these conditions are reflected in epitope-specific GAD65Abs and anti-idiotypic antibodies (anti-Id) against GAD65Abs. We previously reported that 7.8% of T2D patients in the GRADE study have GAD65Abs but found that GAD65Ab positivity was not correlated with beta-cell function, glycated hemoglobin (HbA1c), or fasting glucose levels.

Context

In this study, we aimed to better characterize islet autoantibodies in this T2D cohort. This is an ancillary study to NCT01794143.

Methods

We stringently defined GAD65Ab positivity with a competition assay, analyzed GAD65Ab-specific epitopes, and measured GAD65Ab-specific anti-Id in serum.

Results

Competition assays confirmed that 5.9% of the patients were GAD65Ab positive, but beta-cell function was not associated with GAD65Ab positivity, GAD65Ab epitope specificity or GAD65Ab-specific anti-Id. GAD65-related autoantibody responses in GRADE T2D patients resemble profiles in healthy individuals (low GAD65Ab titers, presence of a single autoantibody, lack of a distinct epitope pattern, and presence of anti-Id to diabetes-associated GAD65Ab). In this T2D cohort, GAD65Ab positivity is likely unrelated to the pathogenesis of beta-cell dysfunction.

Conclusion

Evidence for islet autoimmunity in the pathophysiology of T2D beta-cell dysfunction is growing, but T1D-associated autoantibodies may not accurately reflect the nature of their autoimmune process.

Remission of type 2 diabetes depends on prompt comprehensive lifestyle changes upon diagnosis: How can this "Road to Damascus" experience be supported?

Theoretically, a new diagnosis of type 2 diabetes mellitus (T2DM) requires a dramatic change in an individual's way of life. Weight loss and physical activity can lead to remission of diabetes, which has been associated with a lower risk of developing complications. Today, the importance of a healthy lifestyle is further highlighted by data showing that obesity and diabetes increase the risk of severe complications from coronavirus disease 2019. However, remission rarely occurs in reality, probably due to the inability of people with T2DM to adhere to the intensive lifestyle interventions that are necessary. The complexity of contributing factors may explain why making these changes is so challenging and underscore the fact that there is no magical solution for T2DM. Instead, hard work from both patients and health care providers is needed for the conversion to be achieved. This article calls for more research on the underlying reasons why adhering to a healthy way of life is so difficult for people with diabetes and obesity. Clearly defining these barriers would facilitate the planning of effective policies to promote the adoption of appropriate lifestyle changes early in the course of the disease.

The effects of sodium-glucose cotransporter 2 inhibitors on hepatocellular carcinoma: From molecular mechanisms to potential clinical implications

Hepatocellular carcinoma (HCC) occurs in the setting of prolonged liver inflammation, hepatocyte necrosis and regeneration in patients with cirrhosis. Despite the progress made in the medical management of the disorder during the past decades, the available pharmacological options remain limited, leading to poor survival rates and quality of life for patients with HCC. Sodium-glucose cotransporter 2 inhibitors (SGLT2) originally emerged as drugs for the treatment of hyperglycemia; however, they soon demonstrated important extra-glycemic properties, which led to their evaluation as potential treatments for a wide range of non-metabolic disorders. Evidence from animal studies suggests that SGLT2i have the potential to modulate molecular pathways that affect hallmarks of HCC, including inflammatory responses, cell proliferation, and oxidative stress. The impressive benefits of neurohormonal modulation observed with SGLT2i in congestive heart failure set the stage for human trials in cirrhotic ascites. However, future studies need to evaluate several aspects of the benefit to risk ratio of such a therapeutic strategy, including the co-administration with antineoplastic agents and diuretics, infections, use in hospitalized individuals, renal safety and hypovolemia. In this narrative review, we discuss the putative role of SGLT2i in the treatment of patients with HCC, starting with the mechanisms that could justify a possible benefit and ending with potential clinical implications and areas for future research.

The effect of vitamin D supplementation on glycemic status of elderly people with prediabetes: a 12-month open-label, randomized-controlled study

BACKGROUND

Data on the efficacy of vitamin D in improving the glycemic status of elderly people with prediabetes are scarce. This open-label, randomized-controlled trial investigated the effect of vitamin D supplementation on glycemic markers of Greek people with prediabetes aged 60 years or above, over 12 months.

RESEARCH DESIGN AND METHODS

Participants were randomized to a weekly vitamin D₃ dose of 25,000 IU (n = 45) or nothing (n = 45), on top of lifestyle measures. Anthropometric and glycemic markers were assessed at baseline, 3, 6, and 12 months.

RESULTS

Supplemented participants demonstrated a significant increase in 25(OH)D concentrations at 3,      6,      and 12 months     compared to baseline    . In the intervention group, fasting glucose was decreased at 6 months compared to baseline (96.12 ± 5.51 vs 103.40 ± 12.05 mg/dl, p < 0.01) and glycated hemoglobin was significantly lower at 6 and 12 months compared to baseline [5.82 ± 0.21% vs 5.87 ± 0.21%, p = 0.004 and 5.80 ± 0.23% vs 5.87 ± 0.21%, p < 0.001, respectively].

CONCLUSIONS

Vitamin D could be complementary to lifestyle change strategy for the management of prediabetes in the elderly.

CLINICAL TRIAL REGISTRATION

ISRCTN51643592.

Emergence of microneedles as a potential therapeutics in diabetes mellitus

Diabetes mellitus is a severe condition in which the pancreas produces inadequate insulin or the insulin generated is ineffective for utilisation by the body; as a result, insulin therapy is required for control blood sugar levels in patients having type 1 diabetes and is widely recommended in advanced type 2 diabetes patients with uncontrolled diabetes despite dual oral therapy, while subcutaneous insulin administration using hypodermic injection or pump-mediated infusion is the traditional route of insulin delivery and causes discomfort, needle phobia, reduced adherence, and risk of infection. Therefore, transdermal insulin delivery has been extensively explored as an appealing alternative to subcutaneous approaches for diabetes management which not only is non-invasive and easy, but also avoids first-pass metabolism and prevents gastrointestinal degradation. Microneedles have been commonly investigated in human subjects for transdermal insulin administration because they are minimally invasive and painless. The different types of microneedles developed for the transdermal delivery of anti-diabetic drugs are discussed in this review, including solid, dissolving, hydrogel, coated, and hollow microneedles. Numerous microneedle products have entered the market in recent years. But, before the microneedles can be effectively launched into the market, a significant amount of investigation is required to address the numerous challenges. In conclusion, the use of microneedles in the transdermal system is an area worth investigating because of its significant benefits over the oral route in the delivery of anti-diabetic medications and biosensing of blood sugar levels to assure improved clinical outcomes in diabetes management.