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Hashmi HZ, Khowaja A, Moheet A. Experimental pharmacological approaches to reverse impaired awareness of hypoglycemia-a review. Front Pharmacol 2024; 15:1349004. [PMID: 38323079 PMCID: PMC10844401 DOI: 10.3389/fphar.2024.1349004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Accepted: 01/04/2024] [Indexed: 02/08/2024] Open
Abstract
The colossal global burden of diabetes management is compounded by the serious complication of hypoglycemia. Protective physiologic hormonal and neurogenic counterregulatory responses to hypoglycemia are essential to preserve glucose homeostasis and avert serious morbidity. With recurrent exposure to hypoglycemic episodes over time, these counterregulatory responses to hypoglycemia can diminish, resulting in an impaired awareness of hypoglycemia (IAH). IAH is characterized by sudden neuroglycopenia rather than preceding cautionary autonomic symptoms. IAH increases the risk of subsequent sudden and severe hypoglycemic episodes in patients with diabetes. The postulated causative mechanisms behind IAH are complex and varied. It is therefore challenging to identify a single effective therapeutic strategy. In this review, we closely examine the efficacy and feasibility of a myriad of pharmaceutical interventions in preventing and treating IAH as described in clinical and preclinical studies. Pharmaceutical agents outlined include N-acetyl cysteine, GABA A receptor blockers, opioid receptor antagonists, AMP activated protein kinase agonists, potassium channel openers, dehydroepiandrosterone, metoclopramide, antiadrenergic agents, antidiabetic agents and glucagon.
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Affiliation(s)
- Hiba Z. Hashmi
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, MN, United States
| | - Ameer Khowaja
- Northeast Endocrinology Associates, San Antonio, TX, United States
| | - Amir Moheet
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, MN, United States
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2
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Alam KA, Svalastoga P, Martinez A, Glennon JC, Haavik J. Potassium channels in behavioral brain disorders. Molecular mechanisms and therapeutic potential: A narrative review. Neurosci Biobehav Rev 2023; 152:105301. [PMID: 37414376 DOI: 10.1016/j.neubiorev.2023.105301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/26/2023] [Accepted: 06/30/2023] [Indexed: 07/08/2023]
Abstract
Potassium channels (K+-channels) selectively control the passive flow of potassium ions across biological membranes and thereby also regulate membrane excitability. Genetic variants affecting many of the human K+-channels are well known causes of Mendelian disorders within cardiology, neurology, and endocrinology. K+-channels are also primary targets of many natural toxins from poisonous organisms and drugs used within cardiology and metabolism. As genetic tools are improving and larger clinical samples are being investigated, the spectrum of clinical phenotypes implicated in K+-channels dysfunction is rapidly expanding, notably within immunology, neurosciences, and metabolism. K+-channels that previously were considered to be expressed in only a few organs and to have discrete physiological functions, have recently been found in multiple tissues and with new, unexpected functions. The pleiotropic functions and patterns of expression of K+-channels may provide additional therapeutic opportunities, along with new emerging challenges from off-target effects. Here we review the functions and therapeutic potential of K+-channels, with an emphasis on the nervous system, roles in neuropsychiatric disorders and their involvement in other organ systems and diseases.
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Affiliation(s)
| | - Pernille Svalastoga
- Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway; Children and Youth Clinic, Haukeland University Hospital, Bergen, Norway
| | | | - Jeffrey Colm Glennon
- Conway Institute for Biomolecular and Biomedical Research, School of Medicine, University College Dublin, Dublin, Ireland.
| | - Jan Haavik
- Department of Biomedicine, University of Bergen, Norway; Division of Psychiatry, Haukeland University Hospital, Norway.
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Xiao X, Bi M, Du X, Jiang H. The ATP-sensitive potassium channel: a therapeutic target for neurodegeneration? Expert Opin Ther Targets 2023; 27:517-521. [PMID: 37489110 DOI: 10.1080/14728222.2023.2240023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 07/19/2023] [Indexed: 07/26/2023]
Affiliation(s)
- Xue Xiao
- Physiology, School of Basic Medicine, Medical College of Qingdao University, Qingdao, China
| | - Mingxia Bi
- Physiology, School of Basic Medicine, Medical College of Qingdao University, Qingdao, China
| | - Xixun Du
- Physiology, School of Basic Medicine, Medical College of Qingdao University, Qingdao, China
| | - Hong Jiang
- Physiology, School of Basic Medicine, Medical College of Qingdao University, Qingdao, China
- School of Health and Life Sciences, University of Health and Rehabilitation Sciences, Qingdao City, Shandong, China
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Kaya ST. Effects of diazoxide on streptozotocin induced β cell damage via HSP70/HSP90/TLR4/AMPK signaling pathways. Biotech Histochem 2023; 98:210-219. [PMID: 36740984 DOI: 10.1080/10520295.2023.2168757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
I investigated the effects of diazoxide, a mitochondrial potassium channel opener, on streptozotocin (STZ) induced pancreatic β cell damage via the HSP70/HSP90/TLR4/AMPK signaling pathways in vitro. I used the pancreatic β cell line, 1.1B4, to create four groups: control, STZ treated, diazoxide treated, STZ + diazoxide treated. The STZ treated cells were exposed to 20 µM STZ for 2 h with or without 100 µM diazoxide for 24 h. Total antioxidant status (TAS), total oxidant status (TOS), cell viability and mitochondrial membrane potential (MMP) were measured. Expression of ATP-sensitive potassium channel (KATP) subunits, heat shock protein-70 (HSP70), heat shock protein-90 (HSP90), toll-like receptor 4 (TLR4), AMP-activated protein kinase (AMPK) and some apoptotic proteins were detected using western blotting. Apoptosis was assessed using TUNEL staining. STZ increased TOS and OSI in the pancreatic β cells; however, diazoxide failed to improve oxidative stress. Also, STZ increased tunnel positive cells in the pancreatic β cells. Diazoxide decreased the tunnel positive cells in the STZ treated β cell. STZ decreased MMP; however, diazoxide did not normalize MMP in the STZ induced β cells. Diazoxide increased the HSP70:HSP90 protein expression ratio. STZ decreased expression of AMPK and subunits of KATP channel and increased the expression of caspase-3 and TLR4 protein; diazoxide normalized the expression of all proteins studied. KATP channel opening by diazoxide protects pancreatic β cells against STZ toxicity via HSP70/HSP90/TLR4/AMPK signaling.
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Affiliation(s)
- Salih Tunc Kaya
- Faculty of Arts and Science, Biology Department, Düzce University, Düzce, Turkey
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Baxter F, Baillie N, Forbes S. Study protocol: a randomised controlled proof-of-concept real-world study - does maximising time in range using hybrid closed loop insulin delivery and a low carbohydrate diet restore the glucagon response to hypoglycaemia in adults with type 1 diabetes? BMJ Open 2022; 12:e054958. [PMID: 36600427 PMCID: PMC9772676 DOI: 10.1136/bmjopen-2021-054958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
INTRODUCTION People with type 1 diabetes (T1D) develop an impaired glucagon response to hypoglycaemia within 5 years of diagnosis, increasing their risk of severe hypoglycaemia. It is not known whether eliminating hypoglycaemia and hyperglycaemia allows recovery of this glucagon response. Hybrid closed loop (HCL) technologies improve glycaemic time in range (TIR). However, post-prandial glycaemic excursions are still evident. Consuming a low carbohydrate diet (LCD) may minimise these excursions. METHODS AND ANALYSIS This feasibility study will assess if maximising TIR (glucose ≥3.9 mmol/L≤10 mmol/L) using HCL systems plus an LCD (defined here as <130 g carbohydrate/day) for >8 months, restores the glucagon response to insulin-induced hypoglycaemia. Adults (n=24) with T1D (C-peptide <200 pmol/L), naïve to continuous glucose monitoring (CGM) and HCL systems, will be recruited and randomised to: group 1 (non-HCL) to continue their standard diabetes care with intermittent blinded CGM; or group 2 (HCL-LCD) to use the HCL system and follow a LCD. Baseline data on diet and glycaemia will be collected from all participants. The HCL-LCD group will then enter a 2-week run-in to acclimatise to their devices. Throughout, the HCL-LCD group will have their glucose closely monitored and adjusted aiming for glycaemic TIR >70%. Participants will have their glucagon response to hypoglycaemia measured at the beginning and 8 months later at the study end using a stepped hyperinsulinaemic hypoglycaemic clamp, in combination with the stable isotopes 6,6-2H2-glucose (D2-glucose) and 1,1,2,3,3-2H5-glycerol (D5-glycerol) to assess glucose and glycerol kinetics. The impact of hypoglycaemia on symptoms and cognitive function will be assessed during each clamp study. The primary outcome is the difference in the glucagon response to hypoglycaemia between and within groups at baseline versus study end. ETHICS AND DISSEMINATION Ethical (20/SS/0117)/institutional review board (2021/0001) approval has been obtained. The study will be disseminated by peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER NCT04614168.
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Affiliation(s)
- Faye Baxter
- University of Edinburgh Division of BHF Centre for Cardiovascular Science, Edinburgh, UK
- Department of Diabetes, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Nicola Baillie
- University of Edinburgh Division of BHF Centre for Cardiovascular Science, Edinburgh, UK
- Department of Diabetes, Royal Infirmary of Edinburgh, Edinburgh, UK
| | - Shareen Forbes
- University of Edinburgh Division of BHF Centre for Cardiovascular Science, Edinburgh, UK
- Department of Diabetes, Royal Infirmary of Edinburgh, Edinburgh, UK
- Edmonton Islet Transplant Programme, University of Alberta, Edmonton, Alberta, Canada
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McCrimmon RJ. Remembrance of things past: The consequences of recurrent hypoglycaemia in diabetes. Diabet Med 2022; 39:e14973. [PMID: 36251572 PMCID: PMC10015985 DOI: 10.1111/dme.14973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Revised: 10/03/2022] [Accepted: 10/13/2022] [Indexed: 01/18/2023]
Abstract
AIMS People with type 1 and type 2 diabetes still frequently experience hypoglycaemia, which can be severe, leading to loss of consciousness. This review will examine the cellular consequences of recurrent hypoglycaemia. METHODS This review, based on the Dorothy Hodgkin Lecture given at the Diabetes UK 2022 annual symposium by the author, will discuss our current understanding of the mechanisms by which hypoglycaemia is detected and the consequences of recurrent exposure to hypoglycaemia. RESULTS Glucose-responsive cells found in the periphery as well as multiple areas of the brain are organised in a classical sensori-motor integrative network encompassing peripheral, hindbrain and hypothalamic components. The mechanism used by glucose-responsive neurons to detect hypoglycaemia parallel those of the classical glucose sensor the pancreatic ß-cell, namely in their use of glucokinase, KATP channels and AMP-activated protein kinase. Recurrent exposure to hypoglycaemia results in a series of cellular adaptations that may be designed to increase the resilience of cells to future hypoglycaemia. This review also highlights how hypoglycaemia, as an oxidative stressor, may also exacerbate chronic hyperglycaemia-induced increases in oxidative stress and inflammation, leading to damage to vulnerable brain regions. CONCLUSIONS Impaired awareness of hypoglycaemia follows the adaptation of central glucose-responsive neurons to repeated hypoglycaemia and may represent a form of memory called habituation. In diabetes, recurrent hypoglycaemia may have tissue consequences as a result of a profound disruption in the cellular response to a hypoglycaemic challenge that increases vulnerability to oxidative damage.
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Affiliation(s)
- Rory J. McCrimmon
- Systems Medicine, School of MedicineUniversity of Dundee, Ninewells Hospital and Medical SchoolDundeeUK
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Sanchez-Rangel E, Deajon-Jackson J, Hwang JJ. Pathophysiology and management of hypoglycemia in diabetes. Ann N Y Acad Sci 2022; 1518:25-46. [PMID: 36202764 DOI: 10.1111/nyas.14904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In the century since the discovery of insulin, diabetes has changed from an early death sentence to a manageable chronic disease. This change in longevity and duration of diabetes coupled with significant advances in therapeutic options for patients has fundamentally changed the landscape of diabetes management, particularly in patients with type 1 diabetes mellitus. However, hypoglycemia remains a major barrier to achieving optimal glycemic control. Current understanding of the mechanisms of hypoglycemia has expanded to include not only counter-regulatory hormonal responses but also direct changes in brain glucose, fuel sensing, and utilization, as well as changes in neural networks that modulate behavior, mood, and cognition. Different strategies to prevent and treat hypoglycemia have been developed, including educational strategies, new insulin formulations, delivery devices, novel technologies, and pharmacologic targets. This review article will discuss current literature contributing to our understanding of the myriad of factors that lead to the development of clinically meaningful hypoglycemia and review established and novel therapies for the prevention and treatment of hypoglycemia.
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Affiliation(s)
- Elizabeth Sanchez-Rangel
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Jelani Deajon-Jackson
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Janice Jin Hwang
- Department of Internal Medicine, Section of Endocrinology, Yale University School of Medicine, New Haven, Connecticut, USA.,Division of Endocrinology, Department of Internal Medicine, University of North Carolina - Chapel Hill, Chapel Hill, North Carolina, USA
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Merchant HJ, McNeilly AD. Hypoglycaemia: Still the main drawback of insulin 100 years on: "From man to mouse". Diabet Med 2021; 38:e14721. [PMID: 34653271 DOI: 10.1111/dme.14721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 10/11/2021] [Accepted: 10/13/2021] [Indexed: 12/27/2022]
Abstract
One hundred years on from the initial discovery of insulin, we take this opportunity to reflect on the scientific discoveries that have improved so many lives. From its original crude form, insulin therapy has improved significantly over the past century. Despite this, hypoglycaemia remains an ever-present fear for people with Type 1 diabetes. As such, it is essential that research now looks to minimise the frequency and severity of insulin-induced hypoglycaemia and its complications, some of which can be life-threatening. Over the last century, one thing that has become apparent is the success and need for translational diabetes research. From its origin in dogs, insulin treatment has revolutionised the lives of those with Type 1 diabetes through the coordinated effort of scientists and clinicians. In this review, we recount the more recent research that uses a mouse-to-man approach, specifically in hypoglycaemia research.
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Abstract
The discovery of insulin and its subsequent mass manufacture transformed the lives of people with type 1 and 2 diabetes. Insulin, however, was a drug with a 'dark side'. It brought with it the risk of iatrogenic hypoglycaemia. In this short review, the cellular consequences of recurrent hypoglycaemia, with a particular focus on the brain, are discussed. Using the ventromedial hypothalamus as an exemplar, this review highlights how recurrent hypoglycaemia has an impact on the specialised cells in the brain that are critical to the regulation of glucose homeostasis and the counterregulatory response to hypoglycaemia. In these cells, recurrent hypoglycaemia initiates a series of adaptations that ensure that they are more resilient to subsequent hypoglycaemia, but this leads to impaired hypoglycaemia awareness and a paradoxical increased risk of severe hypoglycaemia. This review also highlights how hypoglycaemia, as an oxidative stressor, may also exacerbate chronic hyperglycaemia-induced increases in oxidative stress and inflammation, leading to damage to vulnerable brain regions (and other end organs) and accelerating cognitive decline. Pre-clinical research indicates that glucose recovery following hypoglycaemia is considered a period where reactive oxygen species generation and oxidative stress are pronounced and can exacerbate the longer-term consequence of chronic hypoglycaemia. It is proposed that prior glycaemic control, hypoglycaemia and the degree of rebound hyperglycaemia interact synergistically to accelerate oxidative stress and inflammation, which may explain why increased glycaemic variability is now increasingly considered a risk factor for the complications of diabetes.
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Affiliation(s)
- Rory J McCrimmon
- Systems Medicine, School of Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, UK.
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Farrell CM, McCrimmon RJ. Clinical approaches to treat impaired awareness of hypoglycaemia. Ther Adv Endocrinol Metab 2021; 12:20420188211000248. [PMID: 33796253 PMCID: PMC7968015 DOI: 10.1177/20420188211000248] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 02/12/2021] [Indexed: 01/25/2023] Open
Abstract
Impaired awareness of hypoglycaemia (IAH) affects between 25% and 30% of all people with type 1 diabetes (T1D) and markedly increases risk of severe hypoglycaemia. This greatly feared complication of T1D impairs quality of life and has a recognised morbidity. People with T1D have an increased propensity to hypoglycaemia as a result of fundamental physiological defects in their ability to respond appropriately to a fall in blood glucose levels. With repeated exposure to low glucose, many then develop a condition referred to as IAH, where there is a reduced ability to perceive the onset of hypoglycaemia and take appropriate corrective action. The management of individuals with IAH relies initially on its identification in the clinic through a detailed exploration of the frequency of hypoglycaemia and an assessment of the individual's ability to recognise these episodes. In this review article, we will address the clinical strategies that may help in the management of the patient with IAH once identified, who may or may not also suffer from problematic hypoglycaemia. The initial focus is on how to identify such patients and then on the variety of approaches involving educational programmes and technological approaches that may be taken to minimise hypoglycaemia risk. No single approach can be advocated for all patients, and it is the role of the health care professional to identify the clinical strategy that best enables their patient to achieve this goal.
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Affiliation(s)
- Catriona M. Farrell
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
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Farrell CM, McNeilly AD, Fournier P, Jones T, Hapca SM, West D, McCrimmon RJ. A randomised controlled study of high intensity exercise as a dishabituating stimulus to improve hypoglycaemia awareness in people with type 1 diabetes: a proof-of-concept study. Diabetologia 2020; 63:853-863. [PMID: 31942669 PMCID: PMC7054230 DOI: 10.1007/s00125-019-05076-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 11/25/2019] [Indexed: 01/08/2023]
Abstract
AIMS/HYPOTHESIS Approximately 25% of people with type 1 diabetes have suppressed counterregulatory hormonal and symptomatic responses to insulin-induced hypoglycaemia, which renders them at increased risk of severe, disabling hypoglycaemia. This is called impaired awareness of hypoglycaemia (IAH), the cause of which is unknown. We recently proposed that IAH develops through habituation, a form of adaptive memory to preceding hypoglycaemia. Consistent with this hypothesis, we demonstrated restoration of defective counterregulatory hormonal responses to hypoglycaemia (referred to as dishabituation) in a rodent model of IAH following introduction of a novel stress stimulus (high intensity training [HIT]). In this proof-of-concept study we sought to further test this hypothesis by examining whether a single episode of HIT would amplify counterregulatory responses to subsequent hypoglycaemia in people with type 1 diabetes who had IAH (assessed by Gold score ≥4, modified Clarke score ≥4 or Dose Adjustment For Normal Eating (DAFNE) hypoglycaemia awareness rating 2 or 3). The primary outcome was the difference in adrenaline response to hypoglycaemia following both a single episode of HIT and rest. METHODS In this randomised, crossover study 12 participants aged between 18 and 55 years with type 1 diabetes for ≥5 years and an HbA1c <75 mmol/mol (9%) were recruited. Individuals were randomised using computer generated block randomisation to start with one episode of HIT (4 × 30 s cycle sprints [2 min recovery] at 150% of maximum wattage achieved during [Formula: see text] assessment) or rest (control). The following day they underwent a 90 min hyperinsulinaemic-hypoglycaemic clamp study at 2.5 mmol/l with measurement of hormonal counterregulatory response, symptom scores and cognitive testing (four-choice reaction time and digit symbol substitution test). Each intervention and subsequent clamp study was separated by at least 2 weeks. The participants and investigators were not blinded to the intervention or measurements during the study. The investigators were blinded to the primary outcome and blood analysis results. RESULTS All participants (six male and six female, age 19-54 years, median [IQR] duration of type 1 diabetes 24.5 [17.3-29.0] years, mean [SEM] HbA1c 56 [3.67] mmol/mol; 7.3% [0.34%]) completed the study (both interventions and two clamps). In comparison with the rest study, a single episode of HIT led to a 29% increase in the adrenaline (epinephrine) response (mean [SEM]) (2286.5 [343.1] vs 2953.8 [384.9] pmol/l); a significant increase in total symptom scores (Edinburgh Hypoglycaemia Symptom Scale: 24.25 [2.960 vs 27.5 [3.9]; p<0.05), and a significant prolongation of four-choice reaction time (591.8 [22.5] vs 659.9 [39.86] ms; p<0.01] during equivalent hypoglycaemia induced the following day. CONCLUSIONS/INTERPRETATION These findings are consistent with the hypothesis that IAH develops in people with type 1 diabetes as a habituated response and that introduction of a novel stressor can restore, at least partially, the adapted counterregulatory hormonal, symptomatic and cognitive responses to hypoglycaemia. TRIAL REGISTRATION ISRCTN15236211.
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Affiliation(s)
- Catriona M Farrell
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, DD19SY, UK
| | - Alison D McNeilly
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, DD19SY, UK
| | - Paul Fournier
- Faculty of Science, School of Human Science, The University of Western Australia, Perth, Australia
| | - Timothy Jones
- Faculty of Health and Medical Sciences, Paediatrics, The University of Western Australia, Perth, Australia
| | - Simona M Hapca
- Computing Science and Mathematics, Faculty of Natural Sciences, University of Stirling, Stirling, UK
| | - Daniel West
- Institute of Cellular Medicine, Faculty of Medical Science, Newcastle University, Newcastle, UK
| | - Rory J McCrimmon
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, DD19SY, UK.
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Reno CM, Bayles J, Skinner A, Fisher SJ. Glibenclamide Prevents Hypoglycemia-Induced Fatal Cardiac Arrhythmias in Rats. Endocrinology 2018; 159:2614-2620. [PMID: 29800118 PMCID: PMC6669817 DOI: 10.1210/en.2018-00419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 05/10/2018] [Indexed: 02/02/2023]
Abstract
Sulfonylureas increase the incidence of severe hypoglycemia in people with type 2 diabetes and might increase the risk of sudden cardiac death. Sulfonylureas stimulate insulin secretion by closing pancreatic ATP-sensitive potassium ion (KATP) channels. To investigate the role of KATP channel modulators on cardiac arrhythmias and mortality in the setting of severe hypoglycemia, adult Sprague-Dawley rats underwent hyperinsulinemic (0.2 U/kg/min) severe hypoglycemic (10 to 15 mg/dL) clamps with continuous electrocardiography. The rats were randomized for treatment with intravenous vehicle (VEH), the sulfonylurea glibenclamide (GLIB; KATP channel blocker; 5 mg/kg/h), or diazoxide (DIAZ; KATP channel opener; 5 mg/kg/h). The results demonstrated that GLIB completely prevented first-degree heart block compared with VEH (0.18 ± 0.09/min) and DIAZ (0.2 ± 0.05/min). Second-degree heart block was significantly reduced with GLIB (0.12 ± 0.1/min) compared with VEH (0.6 ± 0.2/min) and DIAZ (6.9 ± 3/min). The incidence of third-degree heart block was completely prevented by GLIB compared with VEH (67%) and DIAZ (87.5%). Hypoglycemia-induced mortality was completely prevented by GLIB compared with VEH (60%) and DIAZ (82%). In conclusion, although GLIB increases the risk of hypoglycemia by increasing insulin secretion, these results have demonstrated a paradoxical protective role of GLIB against severe hypoglycemia-induced fatal cardiac arrhythmias.
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Affiliation(s)
- Candace M Reno
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Justin Bayles
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Allie Skinner
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Simon J Fisher
- Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- Correspondence: Simon J. Fisher, MD, PhD, Division of Endocrinology, Metabolism, and Diabetes, Department of Internal Medicine, University of Utah School of Medicine, 15 North 2030 East, EIHG Building 533, Room 2110, Salt Lake City, Utah 84112. E-mail:
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13
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McNeilly AD, McCrimmon RJ. Impaired hypoglycaemia awareness in type 1 diabetes: lessons from the lab. Diabetologia 2018; 61:743-750. [PMID: 29417183 PMCID: PMC6448989 DOI: 10.1007/s00125-018-4548-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 10/20/2017] [Indexed: 01/28/2023]
Abstract
Hypoglycaemia remains the most common metabolic adverse effect of insulin and sulfonylurea therapy in diabetes. Repeated exposure to hypoglycaemia leads to a change in the symptom complex that characterises hypoglycaemia, culminating in a clinical phenomenon referred to as impaired awareness of hypoglycaemia (IAH). IAH effects approximately 20-25% of people with type 1 diabetes and increases the risk of severe hypoglycaemia. This review focuses on the mechanisms that are responsible for the much higher frequency of hypoglycaemia in people with diabetes compared with those without, and subsequently how repeated exposure to hypoglycaemia leads to the development of IAH. The mechanisms that result in IAH development are incompletely understood and likely to reflect changes in multiple aspects of the counterregulatory response to hypoglycaemia, from adaptations within glucose and non-glucose-sensing cells to changes in the integrative networks that govern glucose homeostasis. Finally, we propose that the general process that incorporates many of these changes and results in IAH following recurrent hypoglycaemia is a form of adaptive memory called 'habituation'.
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Affiliation(s)
- Alison D McNeilly
- Division of Molecular and Clinical Medicine, Mailbox 12, Level 5, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK
| | - Rory J McCrimmon
- Division of Molecular and Clinical Medicine, Mailbox 12, Level 5, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY, UK.
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Lontchi-Yimagou E, You JY, Carey M, Gabriely I, Shamoon H, Hawkins M. Potential approaches to prevent hypoglycemia-associated autonomic failure. J Investig Med 2018; 66:641-647. [PMID: 29141871 PMCID: PMC6338223 DOI: 10.1136/jim-2017-000582] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2017] [Indexed: 01/27/2023]
Abstract
Clear health benefits are associated with intensive glucose control in type 1 diabetes mellitus (T1DM). However, maintaining near-normal glycemia remains an elusive goal for many patients, in large part owing to the risk of severe hypoglycemia. In fact, recurrent episodes of hypoglycemia lead to 'hypoglycemia-associated autonomic failure' (HAAF), characterized by defective counter-regulatory responses to hypoglycemia. Extensive studies to understand the mechanisms underlying HAAF have revealed multiple potential etiologies, suggesting various approaches to prevent the development of HAAF. In this review, we present an overview of the literature focused on pharmacological approaches that may prevent the development of HAAF. The purported underlying mechanisms of HAAF include: 1) central mechanisms (opioid receptors, ATP-sensitive K+(KATP) channels, adrenergic receptors, serotonin selective receptor inhibitors, γ-aminobuyric acid receptors, N-methyl D-aspartate receptors); 2) hormones (cortisol, estrogen, dehydroepiandrosterone (DHEA) or DHEA sulfate, glucagon-like peptide-1) and 3) nutrients (fructose, free fatty acids, ketones), all of which have been studied vis-à-vis their ability to impact the development of HAAF. A careful review of the current literature reveals many promising therapeutic approaches to treat or reduce this important limitation to optimal glycemic control.
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Affiliation(s)
- Eric Lontchi-Yimagou
- Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Jee Young You
- Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Michelle Carey
- Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA
- Center for Drug Evaluation and Research (CDER), US Food and Drug Administration (FDA), Silver Spring, Maryland, USA
| | - Ilan Gabriely
- Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Harry Shamoon
- Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Meredith Hawkins
- Diabetes Research and Training Center, Albert Einstein College of Medicine, Bronx, New York, USA
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15
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McCrimmon RJ. RD Lawrence Lecture 2015 Old habits are hard to break: lessons from the study of hypoglycaemia. Diabet Med 2017; 34:148-155. [PMID: 27770582 DOI: 10.1111/dme.13277] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/19/2016] [Indexed: 11/29/2022]
Abstract
Despite the introduction of newer technologies and improved insulin formulations, recurrent hypoglycaemia continues to affect the lives of many people with Type 1 and Type 2 diabetes. Developing strategies or therapies designed to prevent or minimize hypoglycaemia risk is of utmost importance to help individuals safely achieve glycaemic targets. Novel, educational or behavioural approaches need to be based on a clear understanding of the mechanisms underpinning both the detection of hypoglycaemia and why repeated exposure to hypoglycaemia leads to the development of a clinical syndrome referred to as impaired awareness of hypoglycaemia. In the present review, I propose that impaired awareness of hypoglycaemia may represent a form of learning called habituation, a response that, at a cellular level, represents a biological adaptation designed to protect the organism from future exposure to that stressor. In diabetes, this survival response to low glucose is, however, overwhelmed by high systemic insulin levels resulting from exogenous insulin therapy, leading to progressively more severe hypoglycaemia. A recognition of the underlying mechanism means that the development of impaired awareness of hypoglycaemia can perhaps be better understood and explained to individuals with diabetes, and novel therapeutic approaches such as dishabituation or cognitive behavioural therapies can be considered.
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Affiliation(s)
- R J McCrimmon
- Division of Molecular and Clinical Medicine, School of Medicine, University of Dundee, Dundee, UK
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16
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Haythorne E, Hamilton DL, Findlay JA, Beall C, McCrimmon RJ, Ashford MLJ. Chronic exposure to K ATP channel openers results in attenuated glucose sensing in hypothalamic GT1-7 neurons. Neuropharmacology 2016; 111:212-222. [PMID: 27618741 DOI: 10.1016/j.neuropharm.2016.09.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 07/06/2016] [Accepted: 09/07/2016] [Indexed: 10/21/2022]
Abstract
Individuals with Type 1 diabetes (T1D) are often exposed to recurrent episodes of hypoglycaemia. This reduces hormonal and behavioural responses that normally counteract low glucose in order to maintain glucose homeostasis, with altered responsiveness of glucose sensing hypothalamic neurons implicated. Although the molecular mechanisms are unknown, pharmacological studies implicate hypothalamic ATP-sensitive potassium channel (KATP) activity, with KATP openers (KCOs) amplifying, through cell hyperpolarization, the response to hypoglycaemia. Although initial findings, using acute hypothalamic KCO delivery, in rats were promising, chronic exposure to the KCO NN414 worsened the responses to subsequent hypoglycaemic challenge. To investigate this further we used GT1-7 cells to explore how NN414 affected glucose-sensing behaviour, the metabolic response of cells to hypoglycaemia and KATP activity. GT1-7 cells exposed to 3 or 24 h NN414 exhibited an attenuated hyperpolarization to subsequent hypoglycaemic challenge or NN414, which correlated with diminished KATP activity. The reduced sensitivity to hypoglycaemia was apparent 24 h after NN414 removal, even though intrinsic KATP activity recovered. The NN414-modified glucose responsiveness was not associated with adaptations in glucose uptake, metabolism or oxidation. KATP inactivation by NN414 was prevented by the concurrent presence of tolbutamide, which maintains KATP closure. Single channel recordings indicate that NN414 alters KATP intrinsic gating inducing a stable closed or inactivated state. These data indicate that exposure of hypothalamic glucose sensing cells to chronic NN414 drives a sustained conformational change to KATP, probably by binding to SUR1, that results in loss of channel sensitivity to intrinsic metabolic factors such as MgADP and small molecule agonists.
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Affiliation(s)
- Elizabeth Haythorne
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - D Lee Hamilton
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - John A Findlay
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - Craig Beall
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - Rory J McCrimmon
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
| | - Michael L J Ashford
- Division of Molecular and Clinical Medicine, School of Medicine, Ninewells Hospital & Medical School, University of Dundee, Dundee, UK.
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17
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De Backer I, Hussain SS, Bloom SR, Gardiner JV. Insights into the role of neuronal glucokinase. Am J Physiol Endocrinol Metab 2016; 311:E42-55. [PMID: 27189932 PMCID: PMC4967152 DOI: 10.1152/ajpendo.00034.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 05/13/2016] [Indexed: 12/17/2022]
Abstract
Glucokinase is a key component of the neuronal glucose-sensing mechanism and is expressed in brain regions that control a range of homeostatic processes. In this review, we detail recently identified roles for neuronal glucokinase in glucose homeostasis and counterregulatory responses to hypoglycemia and in regulating appetite. We describe clinical implications from these advances in our knowledge, especially for developing novel treatments for diabetes and obesity. Further research required to extend our knowledge and help our efforts to tackle the diabetes and obesity epidemics is suggested.
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Affiliation(s)
- Ivan De Backer
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
| | - Sufyan S Hussain
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
| | - Stephen R Bloom
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
| | - James V Gardiner
- Section of Investigative Medicine, Division of Diabetes, Endocrinology and Metabolism, Imperial College London, London, United Kingdom
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18
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Abstract
Intensive glycaemic control reduces the diabetic microvascular disease burden but iatrogenic hypoglycaemia is a major barrier preventing tight glycaemic control because of the limitations of subcutaneous insulin preparations and insulin secretagogues. Severe hypoglycaemia is uncommon early in the disease as robust physiological defences, particularly glucagon and adrenaline release, limit falls in blood glucose whilst associated autonomic symptoms drive patients to take action by ingesting oral carbohydrate. With increasing diabetes duration, glucagon release is progressively impaired and sympatho-adrenal responses are activated at lower glucose levels. Repeated hypoglycaemic episodes contribute to impaired defences, increasing the risk of severe hypoglycaemia in a vicious downward spiral. Managing hypoglycaemia requires a systematic clinical approach with structured insulin self-management training and support of experienced diabetes educators. Judicious use of technologies includes insulin analogues, insulin pump therapy, continuous glucose monitoring, and in a few cases islet cell transplantation. Some individuals require specialist psychological support.
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Affiliation(s)
- Ahmed Iqbal
- Department of Human Metabolism and Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Beech Hill Road, Sheffield, S10 2RX, UK.
| | - Simon Heller
- Department of Human Metabolism and Oncology, University of Sheffield, School of Medicine and Biomedical Sciences, Beech Hill Road, Sheffield, S10 2RX, UK.
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19
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Bonaventura A, Montecucco F, Dallegri F. Update on strategies limiting iatrogenic hypoglycemia. Endocr Connect 2015; 4:R37-45. [PMID: 26099256 PMCID: PMC4512278 DOI: 10.1530/ec-15-0044] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 06/19/2015] [Indexed: 12/17/2022]
Abstract
The prevalence of type 2 diabetes mellitus (T2DM) is increasing all over the world. Targeting good glycemic control is fundamental to avoid the complications of diabetes linked to hyperglycemia. This narrative review is based on material searched for and obtained via PubMed up to April 2015. The search terms we used were: 'hypoglycemia, diabetes, complications' in combination with 'iatrogenic, treatment, symptoms.' Serious complications might occur from an inappropriate treatment of hyperglycemia. The most frequent complication is iatrogenic hypoglycemia that is often associated with autonomic and neuroglycopenic symptoms. Furthermore, hypoglycemia causes acute cardiovascular effects, which may explain some of the typical symptoms: ischemia, QT prolongation, and arrhythmia. With regards to the latter, the night represents a dangerous period because of the major increase in arrhythmias and the prolonged period of hypoglycemia; indeed, sleep has been shown to blunt the sympatho-adrenal response to hypoglycemia. Two main strategies have been implemented to reduce these effects: monitoring blood glucose values and individualized HbA1c goals. Several drugs for the treatment of T2DM are currently available and different combinations have been recommended to achieve individualized glycemic targets, considering age, comorbidities, disease duration, and life expectancy. In conclusion, according to international guidelines, hypoglycemia-avoiding therapy must reach an individualized glycemic goal, which is the lowest HbA1c not causing severe hypoglycemia and preserving awareness of hypoglycemia.
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Affiliation(s)
- Aldo Bonaventura
- Department of Internal MedicineFirst Clinic of Internal Medicine, University of Genoa School of Medicine, IRCCS Azienda Ospedaliera Universitaria San Martino - IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, ItalyDivision of CardiologyFoundation for Medical Researches, Department of Medical Specialties, University of Geneva, Geneva, SwitzerlandDivision of Laboratory MedicineDepartment of Genetics and Laboratory Medicine, Geneva University Hospitals, 4 rue Gabrielle-Perret-Gentil, Avenue de la Roseraie 64, 1205 Geneva, Switzerland
| | - Fabrizio Montecucco
- Department of Internal MedicineFirst Clinic of Internal Medicine, University of Genoa School of Medicine, IRCCS Azienda Ospedaliera Universitaria San Martino - IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, ItalyDivision of CardiologyFoundation for Medical Researches, Department of Medical Specialties, University of Geneva, Geneva, SwitzerlandDivision of Laboratory MedicineDepartment of Genetics and Laboratory Medicine, Geneva University Hospitals, 4 rue Gabrielle-Perret-Gentil, Avenue de la Roseraie 64, 1205 Geneva, Switzerland Department of Internal MedicineFirst Clinic of Internal Medicine, University of Genoa School of Medicine, IRCCS Azienda Ospedaliera Universitaria San Martino - IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, ItalyDivision of CardiologyFoundation for Medical Researches, Department of Medical Specialties, University of Geneva, Geneva, SwitzerlandDivision of Laboratory MedicineDepartment of Genetics and Laboratory Medicine, Geneva University Hospitals, 4 rue Gabrielle-Perret-Gentil, Avenue de la Roseraie 64, 1205 Geneva, Switzerland Department of Internal MedicineFirst Clinic of Internal Medicine, University of Genoa School of Medicine, IRCCS Azienda Ospedaliera Universitaria San Martino - IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, ItalyDivision of CardiologyFoundation for Medical Researches, Department of Medical Specialties, University of Geneva, Geneva, SwitzerlandDivision of Laboratory MedicineDepartment of Genetics and Laboratory Medicine, Geneva University Hospitals, 4 rue Gabrielle-Perret-Gentil, Avenue de la Roseraie 64, 1205 Geneva, Switzerland
| | - Franco Dallegri
- Department of Internal MedicineFirst Clinic of Internal Medicine, University of Genoa School of Medicine, IRCCS Azienda Ospedaliera Universitaria San Martino - IST Istituto Nazionale per la Ricerca sul Cancro, Genoa, ItalyDivision of CardiologyFoundation for Medical Researches, Department of Medical Specialties, University of Geneva, Geneva, SwitzerlandDivision of Laboratory MedicineDepartment of Genetics and Laboratory Medicine, Geneva University Hospitals, 4 rue Gabrielle-Perret-Gentil, Avenue de la Roseraie 64, 1205 Geneva, Switzerland
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