Competition for publication in Diabetologia is greater than ever, and less than 20% of papers are accepted. Of all the high-quality papers that appear in this month’s issue I want to share with you some articles that I find to be of particular interest. These will be featured ‘up front’ in the print issue and here on our website. Sally Marshall, Editor
Chantal Mathieu, Riitta Lahesmaa, Ezio Bonifacio, Peter Achenbach, Timothy Tree
The target organ of immune destruction in type 1 diabetes is the insulin-producing beta cell. As overall beta cell mass is too small for easy imaging or tissue access, the identification of circulating biomarkers reflecting ongoing immune destruction of beta cells would greatly help the prediction and earlier diagnosis of type 1 diabetes, before onset of hyperglycaemia. In this issue, Mathieu et al (https://doi.org/10.1007/s00125-018-4726-8) provide a review of these immunological biomarkers. Some immune biomarkers have reached clinical practice, such as autoantibodies against beta cell antigens, including insulin, GAD, islet antigen-2 or zinc transporter-8. These autoantibodies are highly predictive for type 1 diabetes risk, both in first-degree family members of people with type 1 diabetes and in the general population. Novel immune biomarkers are emerging, in particular, profiles of circulating T lymphocyte subsets and their cytokine-producing activity. High hopes have been placed on the upcoming biomarkers, such as microRNA profiles and metabolomic, lipidomic and other ‘omic’ profiles. These will add power to the more established biomarkers for prediction and diagnosis of type 1 diabetes at earlier stages. The authors note that it is likely that personalised biomarker signatures, combining autoantibodies, T cell profiles and other biomarkers, will be required to categorise at-risk patients, which will facilitate personalised prediction, prevention and treatment approaches.
Emily K. Sims, Carmella Evans-Molina, Sarah A. Tersey, Decio L. Eizirik, and Raghavendra G. Mirmira
Recent studies have highlighted the heterogenous nature of type 1 diabetes and have suggested that, in some cases, beta cell stress and dysfunction may contribute to and exacerbate autoimmune-mediated beta cell destruction. Robust biomarkers of beta cell stress and death are needed to reflect the pathological contributions of beta cells to this process and to monitor the effect of therapeutic agents that target beta cells in type 1 diabetes prevention or treatment efforts. In this issue, Sims et al (https://doi.org/10.1007/s00125-018-4712-1) provide a review summarising the current beta cell biomarkers, including circulating prohormones, RNA species, extracellular vesicles and differentially methylated DNA species. They also discuss ongoing challenges, such as gaining an understanding of how beta cell health changes as disease develops over time. The authors conclude that a well-validated toolkit of biomarkers of beta cell health will allow for a more personalised approach to type 1 diabetes prevention and care. The figure from this review is available as a downloadable slide.
Anitha Pitchika, Manja Jolink, Christiane Winkler, Sandra Hummel, Nadine Hummel, Jan Krumsiek, Gabi Kastenmüller, Jennifer Raab, Olga Kordonouri, Anette-Gabriele Ziegler, Andreas Beyerlein
Children exposed to increased glucose levels in utero may carry additional risks for being overweight and having impaired metabolic health. However, there is only scant evidence from previous studies to support worsening of metabolic health in children of mothers with type 1 diabetes, and potential pathways have not been investigated in detail. In this issue, Pitchika et al (https://doi.org/10.1007/s00125-018-4688-x) report findings from three large studies that examined nearly 2800 children with a first-degree relative with type 1 diabetes. The authors found that children of mothers with type 1 diabetes had a higher risk for being overweight and had increased insulin resistance during childhood and adolescence compared with children of mothers without diabetes. Higher birthweight may partially contribute to this association, but changes in the offspring’s metabolome are unlikely to be part of the causal pathway. These findings indicate that children exposed to maternal type 1 diabetes may need closer attention to combat overweight and metabolic risk in later life.
Mengju Liu, Jian Peng, Ningwen Tai, James A. Pearson, Changyun Hu, Junhua Guo, Lin Hou, Hongyu Zhao, F. Susan Wong, Li Wen
Toll-like receptors (TLRs) are known for their role in innate immunity, but information is sparse on their role in tissue development. In this issue, Liu, Peng et al (https://doi.org/10.1007/s00125-018-4705-0) demonstrate that TLR9 regulates islet beta cell growth and function in a mouse model of diabetes. They report that TLR9 deficiency results in enhanced beta cell growth, leading to improved glucose tolerance, insulin sensitivity and first-phase insulin secretory response. This effect is mediated, in part, by upregulation of CD140a (also known as platelet-derived growth factor receptor-α). This novel finding identifies TLR9 as a potential target for the prevention and/or treatment of diabetes.
Susanne M. Cabrera, Samuel Engle, Mary Kaldunski, Shuang Jia, Rhonda Geoffrey, Pippa Simpson, Aniko Szabo, Cate Speake, Carla J. Greenbaum, Type 1 Diabetes TrialNet CTLA4-Ig (Abatacept) Study Group, Yi-Guang Chen, Martin J. Hessner
Recent studies have drawn attention to the phenotypic heterogeneity that exists among individuals with type 1 diabetes. In trials of disease-modifying immunotherapy conducted at clinical onset, heterogeneity in the rate of disease progression poses challenges in detecting the effect of treatment on preservation of stimulated C-peptide. In this issue, Cabrera et al (https://doi.org/10.1007/s00125-018-4708-x) investigated whether discrete subtypes of type 1 diabetes exist, based on immunoregulatory profiles at clinical onset. They report that levels of innate inflammation at clinical onset were very heterogeneous among newly diagnosed individuals. Importantly, the post-onset duration of persistent insulin secretion was negatively related to baseline inflammation and positively associated with baseline abundance of circulating activated regulatory T cells. Furthermore, in an ancillary analysis of TrialNet CTLA4-Ig trial (TN-09) participants, the therapeutic response to CTLA4-Ig was associated with higher levels of baseline inflammation. These findings suggest that measures that predict the post-onset disease course and the response to therapeutic intervention could enable individual stratification that will lead to the development of individualised therapies.
This issue features a special series of reviews that focus on the newest class of glucose-lowering agents, the sodium–glucose cotransporter (SGLT) inhibitors. Rieg and Vallon (https://doi.org/10.1007/s00125-018-4654-7) begin the series by tracing the development of the SGLT inhibitor class of drugs, including SGLT1 inhibitors, SGLT2 inhibitors and dual inhibitors. Wright and colleagues (https://doi.org/10.1007/s00125-018-4656-5) go on to discuss the mechanisms of actions of these drugs; they explain that SGLT1 and SGLT2 (and GLUT2) are key players in renal glucose transport and describe how inhibition of either SGLT2 or SGLT1 promotes glucose excretion in the urine. However, as discussed by Thomas and Cherney (https://doi.org/10.1007/s00125-018-4669-0), SGLT inhibitors not only affect glucose metabolism, but also body weight, renal function and blood pressure in type 2 diabetes. In terms of their pleiotropic actions, the most striking results so far come from SGLT2 inhibitor studies investigating the cardiovascular effects of these drugs. In their review, Verma and McMurray (https://doi.org/10.1007/s00125-018-4670-7) outline the proposed mechanisms underpinning the unprecedented benefit of reduced cardiovascular disease risk with SGLT2 inhibitor use, observed in people with type 2 diabetes with established cardiovascular disease or multiple cardiovascular risk factors. Despite their glucose-lowering ability, pleiotropic effects and potential cardioprotective outcomes, the place of SGLT2 inhibitors in the management of type 2 diabetes is still hotly debated. To explain why, Lupsa and Inzucchi (https://doi.org/10.1007/s00125-018-4663-6) review the benefits and adverse effects of SGLT2 inhibitors approved for use in the USA and Europe in individuals with type 2 diabetes. What about individuals with type 1 diabetes? Research is much sparser in this area but McCrimmon and Henry (https://doi.org/10.1007/s00125-018-4671-6) discuss the results of two recent 24 week Phase III randomised controlled clinical trials, inTandem3 and DEPICT-1, which studied sotagliflozin (a dual SGLT1/2 inhibitor) and dapagliflozin (an SGLT2 inhibitor), respectively. Wanner and Marx (https://doi.org/10.1007/s00125-018-4678-z) conclude the series by discussing SGLT2 inhibitors in the context of the future of diabetes therapy. They also discuss the effects of SGLT2 inhibitors on other chronic diseases and outline future treatment strategies. This review set is accompanied by an editorial by Sally Marshall (https://doi.org/10.1007/s00125-018-4673-4).
by Toshiaki Ohkuma, Sanne A. E. Peters, Mark Woodward
In several systematic reviews and meta-analyses, diabetes has been associated with the risk of all-site and some site-specific cancers. However, there has been no systematic overview of the evidence available on sex differences in the association between diabetes and cancer. In this issue, Ohkuma et al (https://doi.org/10.1007/s00125-018-4664-5) report that diabetes was associated with a higher risk of all-site cancer in both sexes, but there was a ~6% greater risk in women compared with men. Diabetes was also associated with several site-specific cancers and conferred a significantly greater excess risk in women than men for oral, stomach and kidney cancer, and for leukaemia, but a lower excess risk for liver cancer. These findings indicate the importance of a sex-specific approach to analysis of the role of diabetes for cancer prevention and treatment.
by Geng Zong, Benjamin Lebwohl, Frank B. Hu, Laura Sampson, Lauren W. Dougherty, Walter C. Willett, Andrew T. Chan, Qi Sun
Avoidance of gluten intake is crucial for the management of coeliac disease, in which gluten triggers an autoimmune response. However, adoption of a gluten-free diet among people without apparent gluten-related disorders in the USA and many other countries has become increasingly popular, with the belief that eating a gluten-free diet is associated with health benefits. Despite this perception, evidence is lacking to support or refute the belief that avoidance of gluten is associated with cardiometabolic health benefits in populations without coeliac disease. To fill this knowledge gap, in this issue, Zong, Lebwohl et al (https://doi.org/10.1007/s00125-018-4697-9) report findings from a large-scale analysis in three long-running cohorts of US men and women. They found an inverse association between gluten intake and risk of type 2 diabetes. This association was independent of established diabetes risk factors and appeared to be stronger when added bran intake was also higher. These results suggest that gluten intake is unlikely to exert adverse effects on diabetes risk and that the avoidance of gluten intake, often at the price of reducing fibre intake, should not be recommended for diabetes prevention.
by Lindsey M. Berends, Laura Dearden, Yi Chun L. Tung, Peter Voshol, Denise S. Fernandez-Twinn, Susan E. Ozanne
Low birthweight followed by accelerated postnatal growth is associated with increased risk of type 2 diabetes. It is well established that this is, at least in part, due to programmed peripheral insulin resistance. However, it is unclear if a suboptimal early-life environment also programs central insulin resistance. In this issue, Berends, Dearden et al (https://doi.org/10.1007/s00125-018-4694-z) use a mouse model of diet-induced intra-uterine growth restriction (IUGR) followed by accelerated postnatal catch-up growth to show that a suboptimal early-life environment causes insulin to be less effective at signalling to the brain to reduce food intake in later life. Central insulin resistance in IUGR followed by accelerated postnatal growth was shown to be related to altered expression of insulin-signalling components in the brain, as compared with control offspring born to dams fed a control diet. These findings indicate that promoting accelerated growth in offspring born small for gestational age could have negative effects on long-term metabolic health and that central insulin resistance may contribute to this phenomenon. If extrapolated to humans, these findings also suggest that individuals exposed to a suboptimal early-life environment may be less responsive to both lifestyle and pharmaceutical interventions for metabolic improvements in type 2 diabetes
by Md Abdul Hye Khan, Lauren Kolb, Melissa Skibba, Markus Hartmann, René Blöcher, Ewgenij Proschak, John D. Imig
Despite significant progress in diabetes management, approximately 50% of people with type 2 diabetes fail to achieve therapeutic goals. Consequently, rates of diabetes-associated morbidity and mortality are high, mainly due to complications such as cardiovascular, liver and kidney disease. Poor clinical outcomes with current therapies for diabetes are associated with their lack of ability to simultaneously lower blood glucose and treat comorbidities. Consequently, the majority of patients with type 2 diabetes with a comorbid condition require a multi-drug approach to treatment. In this issue, Hye Khan et al (https://doi.org/10.1007/s00125-018-4685-0) report data from a study in which they developed a novel dual-acting molecule, RB394, that concurrently acts as an inhibitor of soluble epoxide hydrolase (sEH) and an activator of peroxisome proliferator-activated receptor-γ (PPAR-γ). In rat models of the metabolic syndrome and type 2 diabetes, which are associated with comorbid cardiovascular, liver and kidney disease, the authors demonstrated that RB394 not only ameliorated type 2 diabetes and its comorbid conditions, but also treated multiple diabetic complications, including diabetic nephropathy and liver injury. The authors conclude that RB394 is a promising molecule with the potential for development into a therapeutic agent for the metabolic syndrome, type 2 diabetes and associated complications.
by Vishal A. Salunkhe, Rajakrishnan Veluthakal, Steven E. Kahn, Debbie C. Thurmond
Beta cell dysfunction and/or demise are the critical components responsible for the development of prediabetes (defined as impaired fasting glucose and/or impaired glucose tolerance) and progression to frank type 2 diabetes. While tangible progress on improving beta cell function has been made, current clinical approaches do not reliably provide durable glucose control. In this issue, Salunkhe, Veluthakal and colleagues (https://doi.org/10.1007/s00125-018-4658-3) summarise recent advances towards improving beta cell function by improving peripheral insulin sensitivity (as a means of reducing beta cell workload). They explain how a group of factors, which in preclinical studies have been shown to multitask in both beta cells and peripheral insulin-sensitive cells, help to coordinate glucose control. The authors state that new multi-tissue-based therapeutic approaches should dovetail with efforts to formulate precision-medicine-based therapies for the variety of type 2 diabetes phenotypes. They propose that advances in genomic, epigenetic and exosome regulation of the central and tissue-specific landscape of metabolic control should facilitate efforts to refine the phenotypic cluster stratifications for optimal treatment strategies. Integration of these recent advances carries immense potential for the development of more effective medications to achieve durable glucose control in individuals with prediabetes and type 2 diabetes. The figures from this review are available as a downloadable slideset.
by Rafael Simó, Alan W. Stitt, Thomas W. Gardner
Retinal neurodegeneration is an early event in the pathogenesis of diabetic retinopathy. In fact, the ADA has recently defined diabetic retinopathy as a highly tissue-specific neurovascular complication. In this issue, Simó et al (https://doi.org/10.1007/s00125-018-4692-1) provide a critical review on the role of neurodegeneration in the pathogenesis of diabetic retinopathy. A special emphasis is placed on the pathophysiology of the neurovascular unit (NVU). In addition, the authors provide an overview of the usefulness of retinal assessment as an indirect method to explore brain neurodegeneration. Simó and colleagues emphasise that retinal neurodegeneration is a critical endpoint in the development of diabetic retinopathy and that neuroprotection, itself, can be considered a therapeutic target, independent of its potential impact on microvascular disease. The authors conclude that more interventional studies targeting pathogenic pathways that impact on the NVU and which offer both vaso- and neuroprotection are needed. This will be crucial for implementing a timely and efficient personalised medicine approach for diabetic retinopathy. The figures from this review are available as a downloadable slideset.
by Joseph Proietto, Jaret Malloy, Dongliang Zhuang, Mark Arya, Neale D. Cohen, Ferdinandus J. de Looze, Christopher Gilfillan, Paul Griffin, Stephen Hall, Thomas Nathow, Geoffrey S. Oldfield, David N. O’Neal, Adam Roberts, Bronwyn G. A. Stuckey, Dennis Yue, Kristin Taylor, Dennis Kim
Animal and human studies indicate a beneficial effect of methionine aminopeptidase 2 (MetAP2) inhibitors on glycaemic control and other metabolic markers. In this issue, Proietto et al (https://doi.org/10.1007/s00125-018-4677-0) report results from the first study of the effects of the MetAP2 inhibitor beloranib in individuals with type 2 diabetes and obesity. The clinical trial was stopped early due to an unexpected imbalance in venous thromboembolism events in beloranib-treated vs placebo-treated individuals across beloranib clinical trials, during late-stage development of the drug. However, in individuals who had completed 26 weeks of treatment, beloranib produced statistically significant placebo-corrected reductions in both HbA1c (−15.3 mmol/mol [−1.4%]) and body weight (−10%). The authors conclude that these data exemplify MetAP2 inhibition as a novel treatment for metabolic disease. Since this trial, a next-generation MetAP2 inhibitor with an improved safety profile has been developed and has shown encouraging efficacy and safety in an ongoing Phase 2 clinical trial in individuals with type 2 diabetes and obesity.
by Yasuaki Hayashino, Shintaro Okamura, Satoru Tsujii, Hitoshi Ishii, for the Diabetes Distress and Care Registry at Tenri Study Group
Many people with diabetes feel burdened by the never-ending challenge of self-management and experience periods of frustration, anger, fear and helplessness; this is collectively referred to as diabetes distress. High levels of diabetes distress have been associated with poor glycaemic control and a high prevalence of complications in cross-sectional studies. However, there has been a lack of data on the direct association between diabetes-specific distress and all-cause mortality in individuals with diabetes. In this issue, Hayashino et al (https://doi.org/10.1007/s00125-018-4657-4) report on the association between diabetes distress and subsequent risk of all-cause mortality in a Japanese cohort of 1280 women and 2025 men with type 2 diabetes. They found that higher levels of diabetes distress were associated with subsequent risk of all-cause mortality in men with type 2 diabetes, but not in women. These findings provide new evidence to support the targeting of diabetes distress in clinical diabetes care.
by Steef Kurstjens, Janna A. van Diepen, Caro Overmars-Bos, Wynand Alkema, René J. M. Bindels, Frances M. Ashcroft, Cees J. J. Tack, Joost G. J. Hoenderop, Jeroen H. F. de Baaij
Mg2+ deficiency is common in type 2 diabetes, affecting approximately 30% of all individuals with this disease. Nevertheless, the metabolic consequences of hypomagnesaemia (blood Mg2+ <0.7 mmol/l) remain largely unknown. In this issue, Kurstjens et al (https://doi.org/10.1007/s00125-018-4680-5) demonstrate that Mg2+ deficiency in mice protects against high-fat-diet (HFD)-induced obesity, accompanied by improved insulin sensitivity and dyslipidaemia. Compared with HFD-fed mice with normal Mg2+ levels, body weight was lower in HFD-fed mice with low Mg2+ levels. This reduction in weight occurred as a result of increased lipolysis in white adipose tissue and enhanced brown adipose tissue activity. The authors propose that these effects are due to activation of the β-adrenergic system. The data demonstrate the pivotal role of Mg2+ in lipid metabolism and highlight that individuals with type 2 diabetes and hypomagnesaemia may be at particular risk for dyslipidaemia.
by Esra Karakose, Courtney Ackeifi, Peng Wang, Andrew F. Stewart
Reduced numbers of insulin-secreting beta cells underlie both type 1 and type 2 diabetes. Conversely, residual beta cells are present in people with type 2 diabetes, and even after 50 years of type 1 diabetes. The current diabetes armamentarium includes insulin replacement, and drugs that encourage residual beta cells to secrete more insulin and/or enhance sensitivity to insulin. Beta cell replacement, via transplantation of whole pancreas, cadaveric islets, or stem cell-derived beta cells, is another approach. However, as reviewed in this issue by Karakose et al (https://doi.org/10.1007/s00125-018-4639-6), a simpler and more direct alternative would be to expand the numbers of residual beta cells in people with diabetes. Although human beta cells have long been viewed as terminally differentiated and irreversibly quiescent, this notion is changing owing to the recent discovery of pharmacological tools that can induce adult human beta cells to replicate. The authors review progress in this area, and outline remaining obstacles to bringing these novel therapies to patients. The figures from this review are available as a downloadable slideset. [Text supplied by the authors.]
by David Houghton, Timothy Hardy, Christopher Stewart, Linda Errington, Christopher P. Day, Michael I. Trenell, Leah Avery
In type 2 diabetes, treatment variability and disease progression remain poorly understood. However, mechanistic pre-clinical studies indicate that the gut microbiome may be involved. In this issue, Houghton et al (https://doi.org/10.1007/s00125-018-4632-0) report the results of a systematic review, which included eight eligible studies. They found that dietary modification and various pre-, pro- and symbiotic supplements are able to modulate the composition of the gut microbiome and improve glucose control in people with type 2 diabetes. The findings provide important insight but also highlight the need for further well-conducted interventional studies in humans using standardised approaches to allow direct comparisons to be made. The authors note that a deeper understanding of the interaction between the gut microbiome and the pathophysiology of type 2 diabetes will help to lay the foundations to translate preclinical data into clinical practice. If successful, manipulating the microbiome may provide another pathway for the management of type 2 diabetes, enabling a personalised lifestyle approach. [Text supplied by the authors.]
by Jens Oellgaard, Peter Gæde, Peter Rossing, Rasmus Rørth, Lars Køber, Hans-Henrik Parving, Oluf Pedersen
In type 2 diabetes, heart failure is a common, late stage complication that is associated with a high mortality rate that, until recently, has been investigated little. In this issue, Oellgaard and colleagues (https://doi.org/10.1007/s00125-018-4642-y) present the results of a post hoc analysis from 21.2 years follow-up from the Steno-2 study of intensified vs conventional multifactorial intervention in high-risk individuals. Heart failure hospitalisations were as frequent as atherosclerotic cardiovascular disease and were significantly reduced by 70% in the intensive therapy group. The composite endpoints, heart failure hospitalisation or cardiovascular death and heart failure or all-cause mortality, were significantly reduced by 62% and 49%, respectively. Incident heart failure was associated with, but not explained by, prior myocardial infarction. Along with conventional risk factors, elevated plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) at baseline was associated with heart failure and, in the conventional therapy group, an increase in NT-proBNP during the initial 2 years was associated with a poorer outcome. The authors suggest that caregivers should recommend intensified multifactorial intervention to patients with type 2 diabetes to reduce the risk of heart failure. [Text supplied by the authors.]
by Christoph Nowak, Axel C. Carlsson, Carl Johan Östgren, Fredrik H. Nyström, Moudud Alam, Tobias Feldreich, Johan Sundström, Juan-Jesus Carrero, Jerzy Leppert, Pär Hedberg, Egil Henriksen, Antonio C. Cordeiro, Vilmantas Giedraitis, Lars Lind, Erik Ingelsson, Tove Fall, Johan Ärnlöv
There is a need to identify those individuals with type 2 diabetes who are at high risk of heart attack and stroke so that they can receive targeted prevention interventions. In this issue, Ärnlöv’s group at the Karolinska Institute in Sweden (https://doi.org/10.1007/s00125-018-4641-z) assessed whether blood-borne proteins with presumed roles in inflammation and cardiovascular disease might predict the risk of cardiovascular events in type 2 diabetes. Using an 80-protein multiplex assay, the authors replicated four previously described associations and discovered four novel associations. The addition of protein biomarkers to an available risk model improved the prediction of cardiovascular events in people with type 2 diabetes. The authors conclude that, pending further evaluation in a clinical context, these results suggest that targeted multi-protein assays can improve the risk assessment of serious cardiovascular events in type 2 diabetes. [Text supplied by the authors.]
by Brenno Astiarraga, Valéria B. Chueire, Aglécio L. Souza, Ricardo Pereira-Moreira, Sarah Monte Alegre, Andrea Natali, Andrea Tura, Andrea Mari, Ele Ferrannini, Elza Muscelli
In type 2 diabetes, stimulation of insulin secretion by the entry of glucose into the digestive system (i.e. the incretin effect) is impaired. Recent experimental evidence suggests that NEFA might interfere with incretin function. In this issue, Astiarraga, Chueire et al (https://doi.org/10.1007/s00125-018-4633-z) tested this hypothesis by exposing individuals without diabetes to an acute rise in NEFA and by lowering NEFA in participants with type 2 diabetes. The results indicate the presence of a clear asymmetry: while elevation of NEFA disrupted the incretin effect in those without diabetes, lowering NEFA in individuals with type 2 diabetes had no effect. Neither beta cell sensitivity to glucose nor plasma incretin hormone concentrations were altered by NEFA manipulation. Whilst modest elevations of NEFA typically observed in type 2 diabetes are unlikely to be solely responsible for reduced beta cell sensitivity to incretins, they may have some role in disease progression; however, this remains to be demonstrated conclusively. [Text supplied by the authors.]