Diabetologia最新文献

Aims/hypothesis: Homozygous mutations in RFX6 lead to neonatal diabetes accompanied by a hypoplastic pancreas, whereas heterozygous mutations cause MODY. Recent studies have also shown RFX6 variants to be linked with type 2 diabetes. Despite RFX6's known function in islet development, its specific role in diabetes pathogenesis remains unclear. Here, we aimed to understand the mechanisms underlying the impairment of pancreatic islet development and subsequent hypoplasia due to loss-of-function mutations in RFX6.

Methods: We examined regulatory factor X6 (RFX6) expression during human embryonic stem cell (hESC) differentiation into pancreatic islets and re-analysed a single-cell RNA-seq dataset to identify RFX6-specific cell populations during islet development. Furthermore, induced pluripotent stem cell (iPSC) lines lacking RFX6 were generated using CRISPR/Cas9. Various approaches were then employed to explore the consequences of RFX6 loss across different developmental stages. Subsequently, we evaluated transcriptional changes resulting from RFX6 loss through RNA-seq of pancreatic progenitors (PPs) and endocrine progenitors (EPs).

Results: RFX6 expression was detected in PDX1⁺ cells in the hESC-derived posterior foregut (PF). However, in the PPs, RFX6 did not co-localise with pancreatic and duodenal homeobox 1 (PDX1) or NK homeobox 1 (NKX6.1) but instead co-localised with neurogenin 3, NK2 homeobox 2 and islet hormones in the EPs and islets. Single-cell analysis revealed high RFX6 expression levels in endocrine clusters across various hESC-derived pancreatic differentiation stages. Upon differentiating iPSCs lacking RFX6 into pancreatic islets, a significant decrease in PDX1 expression at the PF stage was observed, although this did not affect PPs co-expressing PDX1 and NKX6.1. RNA-seq analysis showed the downregulation of essential genes involved in pancreatic endocrine differentiation, insulin secretion and ion transport due to RFX6 deficiency. Furthermore, RFX6 deficiency resulted in the formation of smaller islet organoids due to increased cellular apoptosis, linked to reduced catalase expression, implying a protective role for RFX6. Overexpression of RFX6 reversed defective phenotypes in RFX6-knockout PPs, EPs and islets.

Conclusions/interpretation: These findings suggest that pancreatic hypoplasia and reduced islet cell formation associated with RFX6 mutations are not due to alterations in PDX1⁺/NKX6.1⁺ PPs but instead result from cellular apoptosis and downregulation of pancreatic endocrine genes.

Data availability: RNA-seq datasets have been deposited in the Zenodo repository with accession link (DOI: https://doi.org/10.5281/zenodo.10656891 ).

Cardiovascular autonomic neuropathy (CAN) is an under-recognised yet highly prevalent microvascular complication of diabetes. CAN affects approximately 20% of people with diabetes, with recent studies highlighting the presence of CAN in prediabetes (impaired glucose tolerance and/or impaired fasting glucose), indicating early involvement of the autonomic nervous system. Understanding of the pathophysiology of CAN continues to evolve, with emerging evidence supporting a potential link between lipid metabolites, mitochondrial dysfunction and genetics. Recent advancements, such as streamlining CAN detection through wearable devices and monitoring of heart rate variability, present simplified and cost-effective approaches for early CAN detection. Further research on the optimal use of the extensive data provided by such devices is required. Despite the lack of specific pharmacological interventions targeting the underlying pathophysiology of autonomic neuropathy, several studies have suggested a favourable impact of newer glucose-lowering agents, such as sodium-glucose cotransporter 2 inhibitors and glucagon-like peptide-1 receptor agonists, where there is a wealth of clinical trial data on the prevention of cardiovascular events. This review delves into recent developments in the area of CAN, with emphasis on practical guidance to recognise and manage this underdiagnosed condition, which significantly increases the risk of cardiovascular events and mortality in diabetes.

Aims/hypothesis: Insulin requirements in the human body undergo continuous changes in response to growth and development. We assessed the life course relationships between insulin demand and insulin adequacy.

Methods: Three independent Chinese cohorts (204 children, aged [mean ± SD] 7.0 ± 0.5 years; 214 adolescents, aged 15.0 ± 1.8 years; 605 adults, aged 41.5 ± 9.3 years), recruited between 1998 and 2013, underwent OGTT tests. Indices of insulin sensitivity and insulin secretion were calculated based on paired glucose/insulin values during fasting, early phase and late phase of OGTT. Insulin demand and insulin adequacy were calculated by standardised major axis (SMA) regression from the paired insulin sensitivity and secretion indices. We derived the natural logarithm of ratio between the exponential functions of insulin adequacy and insulin demand (RAD) index for further evaluating the relationship between insulin demand and adequacy. The risk of abnormal glucose tolerance (AGT) was evaluated by logistic regression analyses. Area under the receiver-operating characteristic curve (AUC-ROC) analyses, net reclassification improvement (NRI) and integrated discrimination improvement (IDI) indices were used to demonstrate the discriminative value of the RAD method model.

Results: Adolescents had the lowest insulin sensitivity and the highest insulin secretion in all phases (fasting, early and late phase) of the OGTT, as compared with children and adults in each phase (all p<0.001). Adolescents had the highest insulin demand in all phases and lowest insulin adequacy in the fasting phase (p<0.001). In general, adults had the lowest insulin adequacy in both the early phase (p>0.05) and late phase (p<0.001) of the OGTT. Adolescents had negative RAD values irrespective of overweight and obesity, while, in general, children and adults had positive RAD values (p<0.001 between age groups in each of the fasting, early and late phases of the OGTT). Participants with RAD values below the 25th percentile had a higher risk of AGT compared with those above the 25th percentile (fasting-phase OR 1.86 [95% CI 1.18, 2.91]; early-phase OR 1.99 [95% CI 1.24, 3.19]; late-phase OR 2.49 [95% CI 1.57, 3.97]). The late-phase RAD index had the best performance in evaluating the risk of AGT compared with the fasting- and early-phase RAD indices (late-phase AUC-ROC = 0.635 [95% CI 0.583, 0.687]; late-phase NRI = 0.350 [95% CI 0.190, 0.510]; late-phase IDI = 0.033 [95% CI 0.015, 0.050]).

Conclusions/interpretation: The relationship between insulin demand and insulin adequacy changed throughout the life course. Adolescents had an imbalanced relationship between insulin demand and insulin adequacy, while, in general, children and adults had a balanced relationship. RAD is a novel index that was used to efficiently describe this relationship and evaluate the risk of AGT.

Aims/hypothesis

Upregulation of serum leucine-rich α-2-glycoprotein 1 (LRG1) has been implicated in diet-induced obesity and metabolic disorders. However, its specific hormonal actions remain unclear. This study aimed to determine whether diet-enhanced serum LRG1 levels promote hyperinsulinaemia by directly stimulating insulin secretion from pancreatic beta cells.

Methods

Human serum samples were obtained from individuals (both male and female) undergoing plastic surgery. Male C57BL/6 wild-type and Lrg1 whole-body knockout (Lrg1^KO) mice were fed a 45% high-fat diet, with serum samples collected every 2 weeks to monitor LRG1 and insulin levels throughout diet-induced obesity. MIN6 beta cells were used to investigate the effects of LRG1 on insulin secretion and intracellular Ca²⁺ release. Antibodies targeting various LRG1 epitopes were used to neutralise LRG1 stimulation in MIN6 cells, and their effectiveness was tested in vivo to assess their ability to prevent LRG1-induced hyperinsulinaemia.

Results

We observed a significant positive association between human serum LRG1 levels and both age and BMI, with elevated levels observed in individuals with vs without type 2 diabetes. In mice fed a high-fat diet, LRG1 upregulation in serum was associated with hyperinsulinaemia. Lrg1 knockout protected mice from diet-induced islet hyperplasia and the loss of beta cell mass. Furthermore, neutralising LRG1 activity prevented the onset of diet-induced hyperinsulinaemia and preserved glucose tolerance. Mechanistically, LRG1 induces inositol triphosphate (IP₃) production and intracellular Ca²⁺ release from the endoplasmic reticulum (ER) in a phospholipase C (PLC)-dependent manner, leading to excessive insulin secretion and ER stress in MIN6 beta cells.

Conclusions/interpretation

In summary, this study identifies LRG1 as a significant contributor to hyperinsulinaemia and beta cell dysfunction. Targeting LRG1 activity emerges as a promising therapeutic approach for addressing diet-induced beta cell dysfunction and managing type 2 diabetes.

Graphical Abstract

Aims/hypothesis

Monogenic diabetes is caused by rare mutations in genes usually implicated in beta cell biology. Common variants of monogenic diabetes genes (MDG) may jointly influence the risk of young-onset type 2 diabetes (YOD, diagnosed before the age of 40 years) and cardiovascular and kidney events.

Methods

Using whole-exome sequencing data, we constructed a weighted polygenic risk score (wPRS) consisting of 135 common variants (minor allele frequency >0.01) of 34 MDG based on r²>0.2 for linkage disequilibrium in a discovery case–control cohort of 453 adults with YOD (median [IQR] age 39.7 [34.9–46.9] years) and 405 without YOD (median [IQR] age 56.7 [50.3–61.0] years), followed by validation in an independent cross-sectional cohort with array-based genotyping for YOD and a prospective cohort of individuals with type 2 diabetes for cardiovascular and kidney events.

Results

In the discovery cohort, the OR of the 135 common variants for YOD ranged from 1.00 to 2.61. In the validation cohort (920 YOD and 4910 non-YOD), top-10%-wPRS was associated with an OR of 1.42 (95% CI 1.03, 1.95, p=0.033) for YOD compared with bottom-10%-wPRS. In 2313 individuals with type 2 diabetes (median [IQR]: age 53.4 [45.4–61.7] years; disease duration 4.0 [1.0–9.0] years) observed for a median (IQR) of 17.5 (14.4–21.8) years, standardised wPRS was associated with increased HR for incident cardiovascular events (1.16 [95% CI 1.06, 1.27], p=0.001), kidney events (1.09 [95% CI 1.02, 1.16], p=0.013) and cardiovascular–kidney events (1.10 [95% CI 1.03, 1.16], p=0.003). Using the ‘bottom-20%-wPRS plus baseline disease duration <5 years’ group as referent, the ‘top-20%-wPRS plus baseline disease duration 5 to <10 years’ group had unadjusted and adjusted HR of 1.60 (95% CI 1.17, 2.19, p=0.003) and 1.62 (95% CI 1.16, 2.26, p=0.005), respectively, for cardiovascular–kidney events compared with 1.38 (95% CI 0.97, 1.98, p=0.075) and 1.06 (95% CI 0.72, 1.57, p=0.752) in the ‘bottom-20%-wPRS plus baseline disease duration ≥10 years’ group.

Conclusions/interpretation

Common variants of MDG increased risk for YOD and cardiovascular–kidney events.

Graphical Abstract

Aims/hypothesis: We aimed to analyse TrialNet Anti-CD3 Prevention (TN10) data using oral minimal model (OMM)-derived indices to characterise the natural history of stage 2 type 1 diabetes in placebo-treated individuals, to describe early metabolic responses to teplizumab and to explore the predictive capacity of OMM measures for disease-free survival rate.

Methods: OMM-estimated insulin secretion, sensitivity and clearance and the disposition index were evaluated at baseline and at 3, 6 and 12 months post randomisation in placebo- and teplizumab-treated groups, and, within each group, in slow- and rapid-progressors (time to stage 3 disease >2 or $\le$ 2 years). OMM metrics were also compared with the standard AUC C-peptide. Percentage changes in CD8⁺ T memory cell and programmed death-1 (PD-1) expression were evaluated in each group.

Results: Baseline metabolic characteristics were similar between 28 placebo- and 39 teplizumab-treated participants. Over 12 months, insulin secretion declined in placebo-treated and rose in teplizumab-treated participants. Within groups, placebo slow-progressors (n=14) maintained insulin secretion and sensitivity, while both declined in placebo rapid-progressors (n=14). Teplizumab slow-progressors (n=28) maintained elevated insulin secretion, while teplizumab rapid-progressors (n=11) experienced mild metabolic decline. Compared with rapid-progressor groups, insulin clearance significantly decreased between baseline and 3, 6 and 12 months in the slow-progressor groups in both treatment arms. In aggregate, both higher baseline insulin secretion (p=0.027) and reduced 12 month insulin clearance (p=0.045) predicted slower progression. A >25% loss of insulin secretion at 3 months had specificity of 0.95 (95% CI 0.86, 1.00) to identify rapid-progressors and correctly classified the 2 year risk for progression in 92% of participants, with a sensitivity of 0.19 (95% CI 0.08, 0.30). OMM-estimated insulin secretion outperformed AUC C-peptide to differentiate groups by treatment or to predict progression. Metabolic changes were paralleled by relative frequency of change in PD-1⁺ CD8⁺ T effector memory cells.

Conclusions/interpretation: OMM measures characterise the metabolic heterogeneity in stage 2 diabetes, identifying differences between rapid- and slow-progressors, and heterogeneous impacts of immunotherapy, suggesting the need to account for these differences when designing and interpreting clinical trials.

Aims/hypothesis

Prediabetes (HbA_1c 39–47 mmol/mol [5.7–6.4%] or fasting glucose 5.6–6.9 mmol/l) is associated with elevated risks of microvascular and macrovascular complications. It is unknown to what extent these risks in prediabetes remain after accounting for progression to diabetes.

Methods

In 10,310 participants from the Atherosclerosis Risk in Communities (ARIC) Study (aged 46–70 years, ~55% women, ~20% Black adults) without diabetes at baseline (1990–1992), we used Cox regression to characterise age- and sex-adjusted associations of prediabetes with ~30 year incidence of complications (composite and separately), including atherosclerotic CVD (ASCVD), heart failure, chronic kidney disease (CKD) and all-cause mortality before and after accounting for intervening incidence of diabetes, modelled as a time-varying variable. We calculated the excess risk of complications in prediabetes remaining after accounting for progression to diabetes.

Results

Of the 60% of adults with prediabetes at baseline, ~30% progressed to diabetes (median time to diabetes, 7 years). Over the maximum follow-up of ~30 years, there were 7069 events (1937 ASCVD, 2109 heart failure, 3288 CKD and 4785 deaths). Prediabetes was modestly associated with risk of any complication (HR 1.21 [95% CI 1.15, 1.27]) vs normoglycaemia. This association remained significant after accounting for progression to diabetes (HR 1.18 [95% CI 1.12, 1.24]) with 85% (95% CI 75, 94%) of the excess risk of any complication in prediabetes remaining. Results were similar for the individual complications.

Conclusions/interpretation

Progression to diabetes explained less than one-quarter of the risks of clinical outcomes associated with prediabetes. Prediabetes contributes to the risk of clinical outcomes even without progression to diabetes.

Graphical Abstract