Intermittent Use of Continuous Glucose Monitoring: A New Paradigm in Treatment of Type 2 Diabetes.

OBJECTIVES: To suggest how continuous glucose monitoring (CGM) may be used intermittently in individuals with type 2 diabetes (T2D). MATERIALS AND METHODS: The use of CGM is largely in those with type 1 diabetes (T1D), in whom it makes sense to use CGM continuously as CGM provides a valuable tool to not only adjust their insulin doses but also to match it with their diet, physical activity, and other lifestyle modifications. In the case of T2D, however, especially for those not on insulin, the use of CGM may not be needed on a continuous basis. The use of CGM on an intermittent basis is rarely discussed in the literature. This article tries to provide clinical situations where CGM can be used intermittently. RESULTS: Intermittent use of CGM defined as the "use of CGM once in 2 or 3 months or a fixed frequency," and may be useful in several situations in those with T2D. We suggest the following indications for the intermittent use of CGM in T2D-newly diagnosed patients where treatment is being started, uncontrolled diabetes where treatment is being altered, starting intensive lifestyle modification, during infections, during preoperative control, in children and adolescents with T2D, as a motivational tool to improve behavioral modification, after metabolic surgery, and in patients on steroids, apart from other indications. CONCLUSION: Intermittent use of CGM in T2D can be useful in special situations and can also be cost saving particularly in resource-constrained regions of the world.

Advanced hybrid closed loop therapy versus conventional treatment in adults with type 1 diabetes (ADAPT): a randomised controlled study.

BACKGROUND: Adults with type 1 diabetes who are treated with multiple daily injections of insulin plus intermittently scanned continuous glucose monitoring (isCGM) can have suboptimal glucose control. We aimed to assess the efficacy of an advanced hybrid closed loop (AHCL) system compared with such therapy in this population. METHODS: The Advanced Hybrid Closed Loop Study in Adult Population with Type 1 Diabetes (ADAPT) trial is a prospective, multicentre, open-label, randomised controlled trial that involved 14 centres in three European countries (France, Germany, and the UK). We enrolled patients who were at least 18 years of age, had a type 1 diabetes duration of at least 2 years, HbA1c of at least 8% (64 mmol/mol), and were using multiple daily injections of insulin plus isCGM (cohort A) or real time continuous glucose monitoring (cohort B) for at least 3 months. Here, only results for cohort A are reported. Participants were randomly allocated 1:1 to AHCL therapy or continuation of multiple daily injections of insulin plus continuous glucose monitoring for 6 months with an investigator-blinded block randomisation procedure. Participants and treating clinicians could not be masked to the arm assignment. The primary endpoint was the between-group difference in mean HbA1c change from baseline to 6 months in the intention-to-treat population using AHCL therapy and those using multiple daily injections of insulin plus isCGM. The primary endpoint was analysed using a repeated measures random-effects model with the study arm and period as factors. Safety endpoints included the number of device deficiencies, severe hypoglycaemic events, diabetic ketoacidosis, and serious adverse events. This study is registered with ClinicalTrials.gov, NCT04235504. FINDINGS: Between July 13, 2020, and March 12, 2021, 105 people were screened and 82 randomly assigned to treatment (41 in each arm). At 6 months, mean HbA1c had decreased by 1·54% (SD 0·73), from 9·00% to 7·32% in the AHCL group and 0·20% (0·80) in the multiple daily injections of insulin plus isCGM from 9·07% to 8·91% (model-based difference -1·42%, 95% CI -1·74 to -1·10; p<0·0001). No diabetic ketoacidosis, severe hypoglycaemia, or serious adverse events related to study devices occurred in either group; two severe hypoglycaemic events occurred in the run-in phase. 15 device-related non-serious adverse events occurred in the AHCL group, compared with three in the multiple daily injections of insulin plus isCGM group. Two serious adverse events occurred (one in each group), these were breast cancer (in one patient in the AHCL group) and intravitreous haemorrhage (in one patient in the multiple daily injections of insulin plus isCGM group). INTERPRETATION: In people with type 1 diabetes using multiple daily injections of insulin plus isCGM and with HbA1c of at least 8%, the use of AHCL confers benefits in terms of glycaemic control beyond those that can be achieved with multiple daily injections of insulin plus isCGM. These data support wider access to AHCL in people with type 1 diabetes not at target glucose levels. FUNDING: Medtronic International Trading Sàrl.

Autoreactive T cell profiles are altered following allogeneic islet transplantation with alemtuzumab induction and re-emerging phenotype is associated with graft function.

Islet transplantation is an effective therapy for life-threatening hypoglycemia, but graft function gradually declines over time in many recipients. We characterized islet-specific T cells in recipients within an islet transplant program favoring alemtuzumab (ATZ) lymphodepleting induction and examined associations with graft function. Fifty-eight recipients were studied: 23 pretransplant and 40 posttransplant (including 5 with pretransplant phenotyping). The proportion with islet-specific T cell responses was not significantly different over time (pre-Tx: 59%; 1-6 m posttransplant: 38%; 7-12 m: 44%; 13-24 m: 47%; and >24 m: 45%). However, phenotype shifted significantly, with IFN-γ-dominated response in the pretransplant group replaced by IL-10-dominated response in the 1-6 m posttransplant group, reverting to predominantly IFN-γ-oriented response in the >24 m group. Clustering analysis of posttransplant responses revealed two main agglomerations, characterized by IFN-γ and IL-10 phenotypes, respectively. IL-10-oriented posttransplant response was associated with relatively low graft function. Recipients within the IL-10+ cluster had a significant decline in C-peptide levels in the period preceding the IL-10 response, but stable graft function following the response. In contrast, an IFN-γ response was associated with subsequently decreased C-peptide. Islet transplantation favoring ATZ induction is associated with an initial altered islet-specific T cell phenotype but reversion toward pretransplant profiles over time. Posttransplant autoreactive T cell phenotype may be a predictor of subsequent graft function.

Structure-functional changes in eNAMPT at high concentrations mediate mouse and human beta cell dysfunction in type 2 diabetes.

AIMS/HYPOTHESIS: Progressive decline in functional beta cell mass is central to the development of type 2 diabetes. Elevated serum levels of extracellular nicotinamide phosphoribosyltransferase (eNAMPT) are associated with beta cell failure in type 2 diabetes and eNAMPT immuno-neutralisation improves glucose tolerance in mouse models of diabetes. Despite this, the effects of eNAMPT on functional beta cell mass are poorly elucidated, with some studies having separately reported beta cell-protective effects of eNAMPT. eNAMPT exists in structurally and functionally distinct monomeric and dimeric forms. Dimerisation is essential for the NAD-biosynthetic capacity of NAMPT. Monomeric eNAMPT does not possess NAD-biosynthetic capacity and may exert distinct NAD-independent effects. This study aimed to fully characterise the structure-functional effects of eNAMPT on pancreatic beta cell functional mass and to relate these to beta cell failure in type 2 diabetes. METHODS: CD-1 mice and serum from obese humans who were without diabetes, with impaired fasting glucose (IFG) or with type 2 diabetes (from the Body Fat, Surgery and Hormone [BodyFatS&H] study) or with or at risk of developing type 2 diabetes (from the VaSera trial) were used in this study. We generated recombinant wild-type and monomeric eNAMPT to explore the effects of eNAMPT on functional beta cell mass in isolated mouse and human islets. Beta cell function was determined by static and dynamic insulin secretion and intracellular calcium microfluorimetry. NAD-biosynthetic capacity of eNAMPT was assessed by colorimetric and fluorescent assays and by native mass spectrometry. Islet cell number was determined by immunohistochemical staining for insulin, glucagon and somatostatin, with islet apoptosis determined by caspase 3/7 activity. Markers of inflammation and beta cell identity were determined by quantitative reverse transcription PCR. Total, monomeric and dimeric eNAMPT and nicotinamide mononucleotide (NMN) were evaluated by ELISA, western blot and fluorometric assay using serum from non-diabetic, glucose intolerant and type 2 diabetic individuals. RESULTS: eNAMPT exerts bimodal and concentration- and structure-functional-dependent effects on beta cell functional mass. At low physiological concentrations (~1 ng/ml), as seen in serum from humans without diabetes, eNAMPT enhances beta cell function through NAD-dependent mechanisms, consistent with eNAMPT being present as a dimer. However, as eNAMPT concentrations rise to ~5 ng/ml, as in type 2 diabetes, eNAMPT begins to adopt a monomeric form and mediates beta cell dysfunction, reduced beta cell identity and number, increased alpha cell number and increased apoptosis, through NAD-independent proinflammatory mechanisms. CONCLUSIONS/INTERPRETATION: We have characterised a novel mechanism of beta cell dysfunction in type 2 diabetes. At low physiological levels, eNAMPT exists in dimer form and maintains beta cell function and identity through NAD-dependent mechanisms. However, as eNAMPT levels rise, as in type 2 diabetes, structure-functional changes occur resulting in marked elevation of monomeric eNAMPT, which induces a diabetic phenotype in pancreatic islets. Strategies to selectively target monomeric eNAMPT could represent promising therapeutic strategies for the treatment of type 2 diabetes.

Challenges in glucoCEST MR body imaging at 3 Tesla.

BACKGROUND: The aim of this study was to translate dynamic glucose enhancement (DGE) body magnetic resonance imaging (MRI) based on the glucose chemical exchange saturation transfer (glucoCEST) signal to a 3 T clinical field strength. METHODS: An infusion protocol for intravenous (i.v.) glucose was optimised using a hyperglycaemic clamp to maximise the chances of detecting exchange-sensitive MRI signal. Numerical simulations were performed to define the optimum parameters for glucoCEST measurements with consideration to physiological conditions. DGE images were acquired for patients with lymphomas and prostate cancer injected i.v. with 20% glucose. RESULTS: The optimised hyperglycaemic clamp infusion based on the DeFronzo method demonstrated higher efficiency and stability of glucose delivery as compared to manual determination of glucose infusion rates. DGE signal sensitivity was found to be dependent on T2, B1 saturation power and integration range. Our results show that motion correction and B0 field inhomogeneity correction are crucial to avoid mistaking signal changes for a glucose response while field drift is a substantial contributor. However, after B0 field drift correction, no significant glucoCEST signal enhancement was observed in tumour regions of all patients in vivo. CONCLUSIONS: Based on our simulated and experimental results, we conclude that glucose-related signal remains elusive at 3 T in body regions, where physiological movements and strong effects of B1 + and B0 render the originally small glucoCEST signal difficult to detect.

Characterization of the Effects of Mesenchymal Stromal Cells on Mouse and Human Islet Function.

Islet transplantation has the potential to cure type 1 diabetes, but current transplantation protocols are not optimal and there is extensive loss of islet ß-cell insulin secretory function during the immediate post-transplantation period. Studies using experimental models of diabetes have shown that the coculture of islets with mesenchymal stromal cells (MSCs) prior to transplantation improves graft function, but several variables differed among research groups (e.g., type of MSCs used and the treatment conditions). We have therefore assessed the effects of MSCs on mouse and human islets by investigating the importance of tissue source for MSCs, the coculture protocol configuration and length, the effect of activated MSCs, and different ß-cell secretory stimuli. MSCs derived from adipose tissue (aMSCs) were the most effective at supporting ß-cell insulin secretion in both mouse and human islets, in a direct contact coculture configuration. Preculture with aMSCs enhanced both phases of glucose-induced insulin secretion and further enhanced secretory responses to the non-nutrients carbachol and arginine. These effects required a coculture period of 48-72 hours and were not dependent on activation of the MSCs. Thus, direct contact coculture with autologous, adipose-derived MSCs for a minimum of 48 hours before implantation is likely to be an effective addition to human islet transplantation protocols. Stem Cells Translational Medicine 2019;8:935&944.

Dynamic Profiling of Insulin Secretion and ATP Generation in Isolated Human and Mouse Islets Reveals Differential Glucose Sensitivity.

BACKGROUND/AIMS: Rodent islets are often used for basic science research but they do not always recapitulate signalling events in human islets. This study evaluated the glucose-dependent responses of human and mouse islets in terms of dynamic insulin secretion, metabolic coupling and the role of glucose transporters. METHODS: Glucose-induced insulin secretion from isolated mouse and human islets was profiled by perifusion and islet ATP levels were measured by chemoluminescence assay. Glucose transporter expression was determined by qPCR and western blotting. RESULTS: Human islets show a left-shifted glucose concentration-insulin secretion profile compared to mouse islets. These data are consistent with glucose transporter expression, with human islets expressing mainly GLUT1 and GLUT3, and GLUT2 being the predominant transporter in mouse islets. Using the GLUT1 inhibitor STF-31 we unveiled an important role for GLUT1 for differences in glucose-induced insulin secretion profiles observed between the two species. CONCLUSION: The high affinity of GLUT1/3 for glucose reflects the left-shifted glucose-induced insulin secretory response of human islets and the impairment of insulin secretion from human islets after STF-31 treatment indicates an important role for GLUT1 in human islet stimulus-secretion coupling. Our data provide further insight into key differences between insulin secretion regulation in mouse and human islets.

Mesenchymal stromal cells improve human islet function through released products and extracellular matrix.

AIMS: The aims of the present study were (i) to determine whether the reported beneficial effects of mesenchymal stromal cells (MSCs) on mouse islet function extend to clinically relevant human tissues (islets and MSCs), enabling translation into improved protocols for clinical human islet transplantation; and (ii) to identify possible mechanisms through which human MSCs influence human islet function. MATERIALS AND METHODS: Human islets were co-cultured with human adipose tissue-derived MSCs (hASCs) or pre-treated with its products - extracellular matrix (ECM) and annexin A1 (ANXA1). Mouse islets were pre-treated with mouse MSC-derived ECM. Islet insulin secretory function was assessed in vitro by radioimmunoassay. Quantitative RT-PCR was used to screen human adipMSCs for potential ligands of human islet G-protein-coupled receptors. RESULTS: We show that co-culture with hASCs improves human islet secretory function in vitro, as measured by glucose-stimulated insulin secretion, confirming previous reports using rodent tissues. Furthermore, we demonstrate that these beneficial effects on islet function can be partly attributed to the MSC-derived products ECM and ANXA1. CONCLUSIONS: Our results suggest that hASCs have the potential to improve the quality of human islets isolated for transplantation therapy of Type 1 diabetes. Furthermore, it may be possible to achieve improvements in human islet quality in a cell-free culture system by using the MSC-derived products ANXA1 and ECM.

Executive Summary of IPITA-TTS Opinion Leaders Report on the Future of ß-Cell Replacement.

The International Pancreas and Islet Transplant Association (IPITA), in conjunction with the Transplantation Society (TTS), convened a workshop to consider the future of pancreas and islet transplantation in the context of potential competing technologies that are under development, including the artificial pancreas, transplantation tolerance, xenotransplantation, encapsulation, stem cell derived beta cells, beta cell proliferation, and endogenous regeneration. Separate workgroups for each topic and then the collective group reviewed the state of the art, hurdles to application, and proposed research agenda for each therapy that would allow widespread application. Herein we present the executive summary of this workshop that focuses on obstacles to application and the research agenda to overcome them; the full length article with detailed background for each topic is published as an online supplement to Transplantation.

Hes3 is expressed in the adult pancreatic islet and regulates gene expression, cell growth, and insulin release.

The transcription factor Hes3 is a component of a signaling pathway that supports the growth of neural stem cells with profound consequences in neurodegenerative disease models. Here we explored whether Hes3 also regulates pancreatic islet cells. We showed that Hes3 is expressed in human and rodent pancreatic islets. In mouse islets it co-localizes with alpha and beta cell markers. We employed the mouse insulinoma cell line MIN6 to perform in vitro characterization and functional studies in conditions known to modulate Hes3 based upon our previous work using neural stem cell cultures. In these conditions, cells showed elevated Hes3 expression and nuclear localization, grew efficiently, and showed higher evoked insulin release responses, compared with serum-containing conditions. They also exhibited higher expression of the transcription factor Pdx1 and insulin. Furthermore, they were responsive to pharmacological treatments with the GLP-1 analog Exendin-4, which increased nuclear Hes3 localization. We employed a transfection approach to address specific functions of Hes3. Hes3 RNA interference opposed cell growth and affected gene expression as revealed by DNA microarrays. Western blotting and PCR approaches specifically showed that Hes3 RNA interference opposes the expression of Pdx1 and insulin. Hes3 overexpression (using a Hes3-GFP fusion construct) confirmed a role of Hes3 in regulating Pdx1 expression. Hes3 RNA interference reduced evoked insulin release. Mice lacking Hes3 exhibited increased islet damage by streptozotocin. These data suggest roles of Hes3 in pancreatic islet function.

Continuous glucose monitoring in patients with insulinoma.

BACKGROUND: Insulinomas are rare neuroendocrine tumours that are usually small and may take time to localize. They cause recurrent life-threatening spontaneous hypoglycaemia. Recurrent hypoglycaemia causes loss of hypoglycaemia awareness, putting the patient at further risk, but this has rarely been described in insulinoma. We describe the utility of continuous glucose monitoring (CGM) in patients with insulinoma. PATIENTS AND METHODS: Three patients, aged 72 years (patient 1), 37 years (patient 2) and 24 years (patient 3), with suspected insulinoma attended our investigation unit, in a university teaching hospital. Biochemical diagnosis was confirmed by elevated plasma insulin and C-peptide during biochemical hypoglycaemia [plasma glucose < 2.2 mM (40 mg/dl)]. Surgery confirmed histology in all. CGM was used to monitor frequency and time of hypoglycaemia during diagnosis and medical treatment, and after definitive surgical treatment. RESULTS: All patients had evidence of hypoglycaemia unawareness. At diagnosis in patients 1-3, CGM revealed 6.1%, 21.9% and 71.0% of time spent in moderate hypoglycaemia (plasma glucose 2.2-3.0 mM), and 1.4%, 11.4% and 48.1% of time in severe hypoglycaemia (plasma glucose < 2.2 mM), respectively. On diazoxide this reduced to 0.6%, 5.4% and 5.7% time in moderate hypoglycaemia, and no severe hypoglycaemia in patients 1 and 3, and 0.5% in patient 2. Octreotide therapy in patients 2 and 3 resulted in 5.8% and 0% of time in moderate hypoglycaemia, respectively, and no severe hypoglycaemia. After surgical excision CGM confirmed cure in all. CONCLUSIONS: CGM in insulinoma is useful in detecting hypoglycaemia, and hypoglycaemia unawareness, monitoring response to medical therapy and for confirming cure postoperatively, and is useful in the management of this uncommon but dangerous condition.