Endogenous Β-cell Function Research Articles

Biomaterials-based nanoparticles conjugated to regulatory T cells provide a modular system for localized delivery of pharmacotherapeutic agents.

Type 1 diabetes (T1D) presents with two therapeutic challenges: the need to correct underlying autoimmunity and restore β-cell mass. We harnessed the unique capacity of regulatory T cells (Tregs) and the T cell receptor (TCR) to direct tolerance induction along with tissue-localized delivery of therapeutic agents to restore endogenous β-cell function. Specifically, we designed a combinatorial therapy involving biomaterials-based poly(lactic-co-glycolic acid) nanoparticles co-loaded with the Treg growth factor, IL-2, and the β-cell regenerative agent, harmine (a tyrosine-regulated kinase 1A [DYRK1A] inhibitor), conjugated to the surface of Tregs. We observed continuous elution of IL-2 and harmine from nanoparticles for at least 7 days in vitro. When conjugated to primary human Tregs, IL-2 nanoparticles provided sufficient IL-2 receptor signaling to support STAT5 phosphorylation for sustained phenotypic stability and viability in culture. Inclusion of poly-L-lysine (PLL) during nanoparticle-cell coupling dramatically increased conjugation efficiency, providing sufficient IL-2 to support in vitro proliferation of IL-2-dependent CTLL-2 cells and primary murine Tregs. In 12-week-old female non-obese diabetic mice, adoptive transfer of IL-2/harmine nanoparticle-conjugated NOD.BDC2.5 Tregs, which express an islet antigen-specific TCR, significantly prevented diabetes demonstrating preserved in vivo viability. These data provide the preclinical basis to develop a biomaterials-optimized cellular therapy to restore immune tolerance and promote β-cell proliferation in T1D through receptor-targeted drug delivery within pancreatic islets.

Comparison of therapeutic effects of mesenchymal stem cells from umbilical cord and bone marrow in the treatment of type 1 diabetes

BackgroundThe therapeutic potential of mesenchymal stem cells (MSCs) in type 1 diabetes (T1D) has been demonstrated in both preclinical and clinical studies. MSCs that have been used in research on T1D are derived from various tissue sources, with bone marrow (BM) and umbilical cord (UC) tissues being the most commonly used. However, the influence of tissue origin on the functional properties and therapeutic effects of MSCs in T1D remains unclear. This study aimed to compare the therapeutic efficacy of UC-MSCs and BM-MSCs in a mouse model of T1D as well as in patients with T1D.MethodsIn non-obese diabetic (NOD) mice, the development of diabetes was accelerated by streptozotocin injections. Thereafter, diabetic mice were randomized and treated intravenously with UC-MSCs, BM-MSCs or phosphate-buffered saline as a control. Blood glucose and serum insulin were measured longitudinally after transplantation. At 14 days post-transplantation, pancreatic tissues were collected to assess insulitis and the β-cell mass. Flow cytometry was performed to evaluate the composition of T lymphocytes in the spleen and pancreatic lymph nodes of the NOD mice. In our retrospective study of patients with T1D, 28 recipients who received insulin therapy alone or a single transplantation of UC-MSCs or BM-MSCs were enrolled. The glycaemic control and β-cell function of the patients during the first year of follow-up were compared.ResultsIn NOD mice, UC-MSC and BM-MSC transplantation showed similar effects on decreasing blood glucose levels and preserving β cells. The regulation of islet autoimmunity was examined, and no significant difference between UC-MSCs and BM-MSCs was observed in the attenuation of insulitis, the decrease in T helper 17 cells or the increase in regulatory T cells. In patients with T1D, MSC transplantation markedly lowered haemoglobin A1c (HbA1c) levels and reduced insulin doses compared to conventional insulin therapy. However, the therapeutic effects were comparable between UC-MSCs and BM-MSCs, and they also exerted similar effects on the endogenous β-cell function in the patients.ConclusionIn conclusion, both UC-MSCs and BM-MSCs exhibited comparable therapeutic effects on improving glycaemic control and preserving β-cell function in T1D. Considering their abundance and higher cell yields, UC-MSCs appear to be more promising than BM-MSCs in clinical applications.Trial registration NCT02763423. Registered on May 5, 2016—Retrospectively registered, https://www.clinicaltrials.gov/.

Verapamil and Its Role in Diabetes

Autoimmune pancreatic β-cell loss and destruction play a key role in the pathogenesis and development of type 1 diabetes, with a prospective increased risk for developing micro- and macrovascular complications. In this regard, orally administrated verapamil, a calcium channel antagonist, usually intended for use as an anti-arrhythmic drug, has previously shown potential beneficial effects on β-cell preservation in new-onset type 1 diabetes. Furthermore, observational data suggest a reduced risk of type 2 diabetes development. The underlying pathophysiological mechanisms are not well investigated and remain widely inconclusive. The aim of this narrative review was to detail the role of verapamil in promoting endogenous β-cell function, potentially eligible for early treatment in type 1 diabetes, and to summarize existing evidence on its effect on glycemia in individuals with type 2 diabetes.

Peptide-YY3-36/glucagon-like peptide-1 combination treatment of obese diabetic mice improves insulin sensitivity associated with recovered pancreatic β-cell function and synergistic activation of discrete hypothalamic and brainstem neuronal circuitries

ObjectiveObesity-linked type 2 diabetes (T2D) is a worldwide health concern and many novel approaches are being considered for its treatment and subsequent prevention of serious comorbidities. Co-administration of glucagon like peptide 1 (GLP-1) and peptide YY3-36 (PYY3-36) renders a synergistic decrease in energy intake in obese men. However, mechanistic details of the synergy between these peptide agonists and their effects on metabolic homeostasis remain relatively scarce. MethodsIn this study, we utilized long-acting analogues of GLP-1 and PYY3-36 (via Fc-peptide conjugation) to better characterize the synergistic pharmacological benefits of their co-administration on body weight and glycaemic regulation in obese and diabetic mouse models. Hyperinsulinemic-euglycemic clamps were used to measure weight-independent effects of Fc-PYY3-36 + Fc-GLP-1 on insulin action. Fluorescent light sheet microscopy analysis of whole brain was performed to assess activation of brain regions. ResultsCo-administration of long-acting Fc-IgG/peptide conjugates of Fc-GLP-1 and Fc-PYY3-36 (specific for PYY receptor-2 (Y2R)) resulted in profound weight loss, restored glucose homeostasis, and recovered endogenous β-cell function in two mouse models of obese T2D. Hyperinsulinemic-euglycemic clamps in C57BLKS/J db/db and diet-induced obese Y2R-deficient (Y2RKO) mice indicated Y2R is required for a weight-independent improvement in peripheral insulin sensitivity and enhanced hepatic glycogenesis. Brain cFos staining demonstrated distinct temporal activation of regions of the hypothalamus and hindbrain following Fc-PYY3-36 + Fc-GLP-1R agonist administration. ConclusionsThese results reveal a therapeutic approach for obesity/T2D that improved insulin sensitivity and restored endogenous β-cell function. These data also highlight the potential association between the gut–brain axis in control of metabolic homeostasis.

Genetic Composition and Autoantibody Titers Model the Probability of Detecting C-Peptide Following Type 1 Diabetes Diagnosis.

We and others previously demonstrated that a type 1 diabetes genetic risk score (GRS) improves the ability to predict disease progression and onset in at-risk subjects with islet autoantibodies. Here, we hypothesized that GRS and islet autoantibodies, combined with age at onset and disease duration, could serve as markers of residual β-cell function following type 1 diabetes diagnosis. Generalized estimating equations were used to investigate whether GRS along with insulinoma-associated protein-2 autoantibody (IA–2A), zinc transporter 8 autoantibody (ZnT8A), and GAD autoantibody (GADA) titers were predictive of C-peptide detection in a largely cross-sectional cohort of 401 subjects with type 1 diabetes (median duration 4.5 years [range 0–60]). Indeed, a combined model with incorporation of disease duration, age at onset, GRS, and titers of IA–2A, ZnT8A, and GADA provided superior capacity to predict C-peptide detection (quasi-likelihood information criterion [QIC] = 334.6) compared with the capacity of disease duration, age at onset, and GRS as the sole parameters (QIC = 359.2). These findings support the need for longitudinal validation of our combinatorial model. The ability to project the rate and extent of decline in residual C-peptide production for individuals with type 1 diabetes could critically inform enrollment and benchmarking for clinical trials where investigators are seeking to preserve or restore endogenous β-cell function.

Proinsulin-specific T-cell responses correlate with estimated c-peptide and predict partial remission duration in type 1 diabetes.

ObjectiveType 1 diabetes (T1D) is an autoimmune disorder in which autoreactive T cells destroy insulin‐producing β‐cells. Interventions that preserve β‐cell function represent a fundamental therapeutic goal in T1D and biomarkers that predict and monitor β‐cell function, and changes in islet autoantigenic signatures are needed. As proinsulin and neoantigens derived from proinsulin peptides (hybrid insulin peptides, HIPs) are important T1D autoantigens, we analysed peripheral blood CD4+ T‐cell autoantigen‐specific proliferative responses and their relationship to estimated β‐cell function.MethodsWe recruited 72 people with and 42 without T1D, including 17 pre‐diabetic islet antibody‐positive and 9 antibody‐negative first‐degree relatives and 16 unrelated healthy controls with T1D‐risk HLA types. We estimated C‐peptide level at 3‐month intervals for 2 years post‐diagnosis and measured CD4+ T‐cell proliferation to proinsulin epitopes and HIPs using an optimised bioassay.ResultsWe show that CD4+ T‐cell proliferation to any islet peptide and to multiple epitopes were significantly more frequent in pre‐diabetic islet antibody‐positive siblings and participants with T1D ≤ 3 months of duration, than in participants with T1D > 3 months or healthy controls. Among participants with T1D and first‐degree relatives, CD4+ T‐cell proliferation occurred most frequently in response to proinsulin33‐63 (full‐length C‐peptide). Proinsulin33‐63‐specific responses were associated with HLA‐DR3‐DQ2 and/or HLA‐DR4/DQ8. In children with T1D, proinsulin33‐63‐specific T‐cell proliferation positively associated with concurrent estimated C‐peptide and predicted survival in honeymoon.ConclusionCD4+ T‐cell proliferative responses to proinsulin‐containing autoantigens are common before and immediately after diagnosis of T1D but decline thereafter. Proinsulin33‐63‐specific CD4+ T‐cell response is a novel marker of estimated residual endogenous β‐cell function and predicts a better 2‐year disease outcome.

1800-P: Cotadutide, a GLP-1/GCG Receptor Co-Agonist, Improves Insulin Sensitivity and Restores Normal Insulin Secretory Capacity in DIO Mice

Cotadutide (MEDI0382) is a peptide with targeted GLP-1/glucagon (Gcg) receptor activity that has beneficial effects on T2D and obesity in humans and mice, and shows marked improvements in NAFLD/NASH in mice. We performed hyperinsulinemic clamps in diet induced obese (DIO) mice to better understand whether improved insulin sensitivity and β-cell function are responsible for the improved glycemia in our clinical studies. Following 28 days of daily dosing with Cotadutide (10 nmol/kg), Liraglutide (5 nmol/kg; GLP-1 agonist) or g1437 (5 nmol/kg; Gcg analog) mice underwent continuous infusion of 4mU/kg/min insulin and [3H]-glucose to assess glucose turnover. Tissue-specific glucose uptake was assessed using 14C-2-deoxyglucose. We observed lower body weight in all groups compared with vehicle control, with g1437 eliciting the largest response and Liraglutide the least. Fasting glucose was significantly higher in g1437 treated mice. Fasting insulin was dramatically lower in Cotadutide and g1437 groups compared with vehicle. Despite an equal rate of human insulin infusion between groups, the total insulin levels during the clamp remained lower in Cotadutide and g1437 treated mice. The glucose infusion rate, to maintain euglycemia ∼130 mg/dL, was significantly higher in Cotadutide treated mice in line with increased glucose disposal rate. Hepatic glucose production was suppressed in all groups, despite significantly lower levels of insulin in Cotadutide and g1437 treated mice. Finally, glucose uptake was elevated in brown adipose tissue in Cotadutide treated mice, which was confirmed in a separate study of [18F]FDG uptake by PET imaging. These experiments demonstrate that Cotadutide improved insulin sensitivity in concert with dramatic reductions for insulin demand, which may result in recovery of endogenous β-cell function in T2D. Disclosure R.C. Laker: Employee; Self; AstraZeneca. L. Lantier: None. O. McGuinness: None. S. Will: Employee; Self; AstraZeneca. Stock/Shareholder; Self; AstraZeneca. K. Kuszpit: None. A.R. Alfaro: None. L. Jermutus: Employee; Self; AstraZeneca. Stock/Shareholder; Self; AstraZeneca. C.J. Rhodes: Employee; Self; AstraZeneca.

Characterization of Signaling Pathways Associated with Pancreatic β-cell Adaptive Flexibility in Compensation of Obesity-linked Diabetes in db/db Mice

The onset of obesity-linked type 2 diabetes (T2D) is marked by an eventual failure in pancreatic β-cell function and mass that is no longer able to compensate for the inherent insulin resistance and increased metabolic load intrinsic to obesity. However, in a commonly used model of T2D, the db/db mouse, β-cells have an inbuilt adaptive flexibility enabling them to effectively adjust insulin production rates relative to the metabolic demand. Pancreatic β-cells from these animals have markedly reduced intracellular insulin stores, yet high rates of (pro)insulin secretion, together with a substantial increase in proinsulin biosynthesis highlighted by expanded rough endoplasmic reticulum and Golgi apparatus. However, when the metabolic overload and/or hyperglycemia is normalized, β-cells from db/db mice quickly restore their insulin stores and normalize secretory function. This demonstrates the β-cell's adaptive flexibility and indicates that therapeutic approaches applied to encourage β-cell rest are capable of restoring endogenous β-cell function. However, mechanisms that regulate β-cell adaptive flexibility are essentially unknown. To gain deeper mechanistic insight into the molecular events underlying β-cell adaptive flexibility in db/db β-cells, we conducted a combined proteomic and post-translational modification specific proteomic (PTMomics) approach on islets from db/db mice and wild-type controls (WT) with or without prior exposure to normal glucose levels. We identified differential modifications of proteins involved in redox homeostasis, protein refolding, K48-linked deubiquitination, mRNA/protein export, focal adhesion, ERK1/2 signaling, and renin-angiotensin-aldosterone signaling, as well as sialyltransferase activity, associated with β-cell adaptive flexibility. These proteins are all related to proinsulin biosynthesis and processing, maturation of insulin secretory granules, and vesicular trafficking-core pathways involved in the adaptation of insulin production to meet metabolic demand. Collectively, this study outlines a novel and comprehensive global PTMome signaling map that highlights important molecular mechanisms related to the adaptive flexibility of β-cell function, providing improved insight into disease pathogenesis of T2D.

Interleukin-2 Therapy of Autoimmunity in Diabetes (ITAD): a phase 2, multicentre, double-blind, randomized, placebo-controlled trial

Type 1 diabetes is a common autoimmune disease due to destruction of pancreatic β cells, resulting in lifelong need for insulin. Evidence suggest that maintaining residual β-cell function can improve glucose control and reduce risk of hypoglycaemia and vascular complications. Non-clinical, preclinical and some preliminary clinical data suggest that low-dose interleukin-2 (IL-2) therapy could block pancreatic β cells destruction by increasing the number of functional regulatory T cells (Tregs) that inhibit islet-specific autoreactive effector T cells (Teffs). However, there is lack of data on the effect of low-dose IL-2 in newly diagnosed children and adolescents with T1D as well as lack of specific data on its potential effect on β-cell function. The ‘ Interleukin-2 Therapy of Autoimmunity in Diabetes (ITAD)’ is a phase 2, multicentre, double-blind, randomised, placebo-controlled trial in children and adolescents (6-18 years; having detectable C-peptide) initiated within 6 weeks of T1D diagnosis. A total of 45 participants will be randomised in a 2:1 ratio to receive either ultra-low dose IL-2 (aldesleukin), at a dose of 0.2 x 10 6 IU/m 2 twice-weekly, given subcutaneously, or placebo, for 6 months. The primary objective is to assess the effects of ultra-low dose aldesleukin administration on endogenous β-cell function as measured by frequent home dried blood spot (DBS) fasting and post-prandial C-peptide in children and adolescents with newly diagnosed T1D. The secondary objectives are: 1) to assess the efficacy of regular dosing of aldesleukin in increasing Treg levels; 2) to confirm the clinical safety and tolerability of ultra-low dose aldesleukin; 3) to assess changes in the immune system indicating benefit or potential risk for future gains/loss in β-cell function and immune function; 4) to assess treatment effect on glycaemic control. Trial registration: EudraCT 2017-002126-20 (06/02/2019)

Interleukin-2 Therapy of Autoimmunity in Diabetes (ITAD): a phase 2, multicentre, double-blind, randomized, placebo-controlled trial.

Type 1 diabetes is a common autoimmune disease due to destruction of pancreatic β cells, resulting in lifelong need for insulin. Evidence suggest that maintaining residual β-cell function can improve glucose control and reduce risk of hypoglycaemia and vascular complications. Non-clinical, preclinical and some preliminary clinical data suggest that low-dose interleukin-2 (IL-2) therapy could block pancreatic β cells destruction by increasing the number of functional regulatory T cells (Tregs) that inhibit islet-specific autoreactive effector T cells (Teffs). However, there is lack of data on the effect of low-dose IL-2 in newly diagnosed children and adolescents with T1D as well as lack of specific data on its potential effect on β-cell function. The ' Interleukin-2 Therapy of Autoimmunity in Diabetes (ITAD)' is a phase 2, multicentre, double-blind, randomised, placebo-controlled trial in children and adolescents (6-18 years; having detectable C-peptide) initiated within 6 weeks of T1D diagnosis. A total of 45 participants will be randomised in a 2:1 ratio to receive either ultra-low dose IL-2 (aldesleukin), at a dose of 0.2 x 10 6 IU/m 2 twice-weekly, given subcutaneously, or placebo, for 6 months. The primary objective is to assess the effects of ultra-low dose aldesleukin administration on endogenous β-cell function as measured by frequent home dried blood spot (DBS) fasting and post-prandial C-peptide in children and adolescents with newly diagnosed T1D. The secondary objectives are: 1) to assess the efficacy of regular dosing of aldesleukin in increasing Treg levels; 2) to confirm the clinical safety and tolerability of ultra-low dose aldesleukin; 3) to assess changes in the immune system indicating benefit or potential risk for future gains/loss in β-cell function and immune function; 4) to assess treatment effect on glycaemic control. Trial registration: EudraCT 2017-002126-20 (06/02/2019).

Serum complement C3 and islet β-cell function in patients with type 2 diabetes: A 4.6-year prospective follow-up study.

Serum complement C3 has been shown to contribute to the incidence of type 2 diabetes (T2D), but how serum complement C3 affects islet β-cell function throughout the course of T2D is unclear. This study explored whether serum complement C3 is independently associated with changes in islet β-cell function over time in patients with T2D. Serum complement C3 was measured, and endogenous β-cell function was evaluated by area under the C-peptide curve (AUCcp) during an oral glucose tolerance test (OGTT) in 411 patients with T2D at baseline from 2011 to 2015. Next, 347 of those patients with available data were pooled for a final follow-up analysis from 2014 to 2018. Changes in islet β-cell function at follow-up were evaluated by AUCcp percentage changes (ΔAUCcp%). In addition, other possible clinical risks for diabetes were also examined. The 347 patients included in the analysis had a diabetes duration of 4.84 ± 3.63 years at baseline. Baseline serum complement C3 (baseline C3) levels were positively correlated with baseline natural logarithm of AUCcp (lnAUCcp) (n = 347, r = 0.288, p < 0.001), and baseline C3 was independently associated with baseline lnAUCcp (β = 0.17, t = 3.52, p < 0.001) after adjustment for baseline glycemic status and other clinical confounders by multivariate liner regression analysis. Compared with the baseline values, complement C3 changes (ΔC3) and ΔAUCcp% was -0.15 ± 0.28 mg/ml and -17.2 ± 18.4%, respectively, at a follow-up visit 4.57 ± 0.78 years later. Moreover, ΔC3 was positively correlated with ΔAUCcp% (n = 347, r = 0.302, p < 0.001). Furthermore, each 0.1 mg/ml increase in ΔC3 was associated with a higher ΔAUCcp% (1.41% [95% CI, 0.82-2.00%]) after adjusting for changes in glycemic status and other clinical confounders at follow-up. In addition to serum complement C3 being independently associated with islet β-cell function at baseline, its changes were also independently associated with changes in islet β-cell function over time in patients with T2D.

Increased Interleukin-35 Levels in Patients With Type 1 Diabetes With Remaining C-Peptide.

Many patients with long-standing type 1 diabetes have remaining functional β-cells. This study investigated immunological differences between patients with or without measurable remaining endogenous insulin production after ≥10 years duration of disease. Patients (n = 113; ≥18 years of age) with type 1 diabetes and with disease duration of ≥10 years were recruited at Uppsala University Hospital. Residual β-cell function was determined with an ultrasensitive C-peptide ELISA. Circulating cytokines, including interleukin-35 (IL-35), were determined in plasma. Additional blood samples were collected from 14 of the identified C-peptide-positive patients and 12 of the C-peptide-negative patients, as well as from 15 healthy control subjects, and were used for immediate investigation of peripheral blood mononuclear cells. The blood concentration of the cytokine IL-35 was markedly lower in C-peptide-negative patients, and this was associated with a simultaneous decrease in the proportion of IL-35+ regulatory T cells (Tregs), IL-35+ regulatory B cells, and IL-35-producing CD8+Foxp3+ cells. IL-35 has previously been shown to maintain the phenotype of Tregs, block the differentiation of T-helper 17 cells, and thereby dampen immune assaults to β-cells. We found that the proportions of IL-17a+ cells among the Tregs, CD4+ T cells, and CD8+ T cells were lower in the C-peptide-positive patients. Patients with remaining endogenous β-cell function after >10 years duration of type 1 diabetes differ immunologically from other patients with long-standing type 1 diabetes. In particular, they have a much higher IL-35 production.

Demonstration of an intrinsic relationship between endogenous C-peptide concentration and determinants of glycemic control in type 1 diabetes following islet transplantation.

Maintenance of endogenous pancreatic β-cell function could be an important goal in the management of type 1 diabetes. However, the impact of stimulated C-peptide level on overall glycemic control is unknown. The relationship between C-peptide and parameters of glucose control was therefore characterized in a cohort with rapidly changing β-cell function following islet transplantation. Standardized mixed-meal tolerance test was undertaken in 12 consecutive islet recipients at 1-6-month intervals, with graft function determined by 90-min stimulated C-peptide. Continuous glucose monitoring was undertaken in the week preceding each assessment and the relationship between C-peptide and glucose control evaluated by mixed Poisson regression. Recipients completed 5 (1-14) [median (range)] clinical assessments over 18 (1-51) months posttransplant encompassing a wide range of stimulated C-peptide levels (7-2,622 pmol/L). Increasing β-cell function across predefined C-peptide groups was associated with reduced insulin dose, HbA1c, mean glucose (low [<200 pmol/L] 10.7 vs. excellent [>1,000 pmol/L] 7.5 mmol/L), and glucose SD (low, 4.4 vs. excellent, 1.4 mmol/L). Highly statistically significant continuous associations between stimulated C-peptide and mean interstitial glucose (lower by 2.5% [95% CI 1.5-3.5%] per 100 pmol/L higher C-peptide), glucose SD, time outside glucose target range, and measures of hyper-/hypoglycemia risk were confirmed. Repeated assessment of islet transplant recipients has enabled modeling of the relationship between endogenous β-cell function and measures of glycemic control providing quantitative estimates of likely impact of an acute change in β-cell function in individuals with type 1 diabetes.

The association between postprandial urinary C‐peptide creatinine ratio and the treatment response to liraglutide: a multi‐centre observational study

The response to glucagon-like peptide1 receptor agonist treatment may be influenced by endogenous β-cell function. We investigated whether urinary C-peptide creatinine ratio assessed before or during liraglutide treatment was associated with treatment response. A single, outpatient urine sample for urinary C-peptide creatinine ratio was collected 2h after the largest meal of the day among two separate groups: (1) subjects initiating liraglutide (0.6→1.2mg daily) or (2) subjects already treated with liraglutide for 20-32weeks. The associations between pretreatment and on-treatment urinary C-peptide creatinine ratio and HbA1c change at 32weeks were assessed using univariate and multivariate analyses (the ratio was logarithm transformed for multivariate analyses). Changes in HbA1c according to pretreatment urinary C-peptide creatinine ratio quartiles are shown. One hundred and sixteen subjects (70 pretreatment, 46 on treatment) with Type2 diabetes from 10 diabetes centres were studied. In univariate analyses, neither pretreatment nor on-treatment urinary C-peptide creatinine ratio correlated with HbA1c change (Spearman rank correlation coefficient, r=-0.17, P=0.17 and r=-0.20, P=0.19, respectively). In multi-linear regression analyses, entering baseline HbA1c and log urinary C-peptide creatinine ratio, pretreatment and on-treatment log urinary C-peptide creatinine ratio became significantly associated with HbA1c change (P=0.048 and P=0.040, respectively). Mean (sd) HbA1c changes from baseline in quartiles1 to 4 of pretreatment urinary C-peptide creatinine ratio were -3±17mmol/mol (-0.3±1.6%) (P=0.52), -12±15mmol/mol (-1.1±1.4%) (P=0.003), -11±13mmol/mol (-1.0±1.2%) (P=0.002) and -12±17mmol/mol (-1.1±1.6%) (P=0.016), respectively. Postprandial urinary C-peptide creatinine ratios before and during liraglutide treatment were weakly associated with the glycaemic response to treatment. Low pretreatment urinary C-peptide creatinine ratio may be more useful than higher values by predicting poorer glycaemic response.

Lack of association between residual insulin production and glucagon response to hypoglycemia in youth with short duration of type 1 diabetes.

OBJECTIVETo examine the loss of glucagon response to hypoglycemia and its relationship with residual β-cell function early in the course of type 1 diabetes (T1D) in youth.RESEARCH DESIGN AND METHODSTwenty-one youth with T1D duration <1 year (ages 8–18 years, T1D duration 6–52 weeks) underwent mixed-meal tolerance tests (MMTTs) to assess residual β-cell function and hypoglycemic clamps to assess glucagon responses to hypoglycemia. Glucagon responses to hypoglycemia in T1D subjects were compared with those in 12 nondiabetic young adults (ages 19–25 years).RESULTSPeak MMTT-stimulated C-peptide levels (range 0.12–1.43) were ≥0.2 nmol/L in all but one T1D subject. As expected, the median of glucagon responses to hypoglycemia in the T1D subjects (18 pg/mL [interquartile range 7–32]) was significantly reduced compared with the responses in nondiabetic control subjects (38 pg/mL [19–66], P = 0.02). However, there was no correlation between the incremental increase in plasma glucagon during the hypoglycemic clamp and the incremental increase and peak plasma C-peptide level during the MMTT. Similarly, the seven T1D subjects who failed to achieve an increase in glucagon ≥12 pg/mL (i.e., 3 SD above baseline values) had C-peptide response ≥0.2 nmol/L (0.54–1.12), and the one T1D subject with peak stimulated <0.2 nmol/L had a 14 pg/mL increase in plasma glucagon in response to hypoglycemia.CONCLUSIONSImpaired plasma glucagon responses to hypoglycemia are evident in youth with T1D during the first year of the disease. Moreover, defective and absent glucagon responses to hypoglycemia were observed in patients who retained clinically important residual endogenous β-cell function.

Hyperglycaemia is associated with impaired pulsatile insulin secretion: effect of basal insulin therapy

Postprandial insulin pulsatility is impaired in patients with type 2 diabetes, but the effects of exogenous insulin therapy on pulsatile insulin secretion are not known. We addressed, whether pulsatile insulin secretion is related to glycaemic control, whether basal insulin supplementation increases postprandial insulin secretion, and if so, is this accomplished by a specific improvement in pulsatile insulin secretion? Fourteen patients with type 2 diabetes underwent a mixed meal test before and after an 8-week treatment period with insulin glargine. Glucose, insulin and C-peptide levels were measured, and insulin pulsatility was determined by deconvolution analysis. Insulin treatment lowered fasting glycaemia from 179.6 ± 7.5 mg/dl to 117.6 ± 6.5 mg/dl (p < 0.001). Postprandial insulin and C-peptide levels increased significantly after the treatment period (p < 0.0001). The total calculated insulin secretion rate increased with insulin treatment (p = 0.0039), with non-significant increases in both pulsatile and non-pulsatile insulin secretion. Insulin pulse frequency was unchanged by the intervention. There was an inverse relationship between fasting and postprandial glycaemia and insulin pulse mass (r(2) = 0.51 and 0.56, respectively), whereas non-pulsatile insulin secretion was unrelated to either fasting or postprandial glucose concentrations (r(2) = 0.0073 and 0.031). Hyperglycaemia in type 2 diabetes is associated with a reduction in postprandial insulin secretion, specifically through a reduction in insulin pulsatility. Reducing chronic hyperglycaemia by basal insulin therapy enhances endogenous β-cell function in the postprandial state. These data support the use of basal insulin regimens in the pharmacotherapy of overtly hyperglycaemic patients with type 2 diabetes.

Sensor augmented pump therapy from onset of type 1 diabetes: late follow-up results of the Pediatric Onset Study

To evaluate the metabolic control and β-cell function 1 yr after the end of the European multicentre randomized Pediatric Onset Study. Of 154 study patients, 131 were re-examined 24 months after type 1 diabetes onset (49.6% boys, age at onset 8.9 ± 4.3 yrs). Of which, 62 patients belonged to the primary group of the main study applying a sensor-augmented pump system during the first yr and 69 patients to the control group performing conventional insulin pump therapy with self-monitoring blood glucose. HbA1c, fasting blood glucose, and C-peptide were centrally measured (Clinical Trail Registration Number: ISRCTN05450731). At 24 months, i.e., 1 yr after the end of the interventional study, 52.4% of the patients used the sensor-augmented pump system, 46.0% conventional pump, and 1.6% multiple daily injections. HbA1c was 7.6 ± 1.3% in the primary and 7.7 ± 1.2% in the control group (p = 0.493). Frequent sensor use during the first yr was associated with statistically insignificant lowering of the HbA1c at 24 months (p = 0.236) as compared with irregular or no sensor use (7.4 ± 1.0% vs. 7.7 ± 1.3%). Although fasting C-peptide was not clearly different between the primary and control group (0.13 ± 0.17 vs. 0.09 ± 0.10 nmol/L, p = 0.121), patients with frequent sensor use had significantly less C-peptide loss within 24 months (C-peptide reduction 0.02 ± 0.18 vs. 0.07 ± 0.11 nmol/L, p = 0.046). There was no difference between the groups regarding daily insulin requirements. Sensor-augmented pump therapy from onset of diabetes may lead to better long-term glycemic control and help to preserve endogenous β-cell function, if patients comply with frequent use of continuous glucose monitoring.

Recovery of Endogenous β-Cell Function in Nonhuman Primates After Chemical Diabetes Induction and Islet Transplantation

OBJECTIVE—To describe the ability of nonhuman primate endocrine pancreata to reestablish endogenous insulin production after chemical β-cell destruction.RESEARCH DESIGN AND METHODS—Eleven monkeys (Macaca fascicularis) were rendered diabetic with streptozotocin. Eight diabetic monkeys received intraportal porcine islet transplantation.RESULTS—Two monkeys transplanted after 75 days of type 1 diabetes showed recovery of endogenous C-peptide production a few weeks after transplantation, concomitant with graft failure. Histological analysis of the pancreas of these monkeys showed insulin-positive cells, single or in small aggregates, scattered in the pancreas and adjacent to ducts. Interestingly, numerous CK19+ cells costained with proinsulin and PDX-1 antibodies. Furthermore, the peculiar double phenotype glucagon-positive/GLUT2+ was observed. In these monkeys as well as in all others, the original islets showed no insulin staining.CONCLUSIONS—Our data provide evidence that, in nonhuman primates, the pancreas can reestablish endogenous insulin production after chemical β-cell destruction. This seems to be a nongeneralizable event with only 2 out of 11 monkeys recovering β-cell function. In these two monkeys, younger age and islet graft behavior might have played a role in triggering endogenous β-cell recovery.

Exploring the Substitution of Exenatide for Insulin in Patients With Type 2 Diabetes Treated With Insulin in Combination With Oral Antidiabetes Agents

This 16-week study explored the safety of substituting exenatide for insulin in patients with type 2 diabetes using insulin in combination with oral antidiabetes agents. Successful maintenance of glycemic control was predefined as an A1C increase of < 0.5%. A total of 49 patients (aged 53 +/- 8 years, with BMI 34 +/- 4 kg/m2, A1C 8.1 +/- 1.1%, and duration of diabetes 11 +/- 7 years) were randomized to either substitute exenatide for insulin or remain on their current insulin regimen. Patients who either completed > or = 8 weeks of study or discontinued because of loss of glycemic control were included in primary efficacy analysis. A total of 62% (18 of 29) of the exenatide-treated patients maintained glycemic control compared with 81% (13 of 16) of the insulin-treated patients. Of the 11 exenatide-treated patients who did not maintain control, 5 discontinued before week 16 because of loss of glucose control. The overall safety profile was generally consistent with previous exenatide trials. The mean overall hypoglycemia rates were 1.72 and 0.97 events/patient-year for the exenatide and insulin reference groups, respectively. This pilot study suggests that it is feasible to sustain glycemic control when substituting exenatide for insulin. Although it is not possible to characterize clear predictors of outcome given the size and exploratory nature of the study, the data suggest that patients with longer disease duration, who are taking higher doses of insulin and have less endogenous beta-cell function, may experience deterioration in glucose control if exenatide is substituted for insulin therapy.

Five-Year Follow-Up After Clinical Islet Transplantation

Islet transplantation can restore endogenous beta-cell function to subjects with type 1 diabetes. Sixty-five patients received an islet transplant in Edmonton as of 1 November 2004. Their mean age was 42.9 +/- 1.2 years, their mean duration of diabetes was 27.1 +/- 1.3 years, and 57% were women. The main indication was problematic hypoglycemia. Forty-four patients completed the islet transplant as defined by insulin independence, and three further patients received >16,000 islet equivalents (IE)/kg but remained on insulin and are deemed complete. Those who became insulin independent received a total of 799,912 +/- 30,220 IE (11,910 +/- 469 IE/kg). Five subjects became insulin independent after one transplant. Fifty-two patients had two transplants, and 11 subjects had three transplants. In the completed patients, 5-year follow-up reveals that the majority ( approximately 80%) have C-peptide present post-islet transplant, but only a minority ( approximately 10%) maintain insulin independence. The median duration of insulin independence was 15 months (interquartile range 6.2-25.5). The HbA(1c) (A1C) level was well controlled in those off insulin (6.4% [6.1-6.7]) and in those back on insulin but C-peptide positive (6.7% [5.9-7.5]) and higher in those who lost all graft function (9.0% [6.7-9.3]) (P < 0.05). Those who resumed insulin therapy did not appear more insulin resistant compared with those off insulin and required half their pretransplant daily dose of insulin but had a lower increment of C-peptide to a standard meal challenge (0.44 +/- 0.06 vs. 0.76 +/- 0.06 nmol/l, P < 0.001). The Hypoglycemic score and lability index both improved significantly posttransplant. In the 128 procedures performed, bleeding occurred in 15 and branch portal vein thrombosis in 5 subjects. Complications of immunosuppressive therapy included mouth ulcers, diarrhea, anemia, and ovarian cysts. Of the 47 completed patients, 4 required retinal laser photocoagulation or vitrectomy and 5 patients with microalbuminuria developed macroproteinuria. The need for multiple antihypertensive medications increased from 6% pretransplant to 42% posttransplant, while the use of statin therapy increased from 23 to 83% posttransplant. There was no change in the neurothesiometer scores pre- versus posttransplant. In conclusion, islet transplantation can relieve glucose instability and problems with hypoglycemia. C-peptide secretion was maintained in the majority of subjects for up to 5 years, although most reverted to using some insulin. The results, though promising, still point to the need for further progress in the availability of transplantable islets, improving islet engraftment, preserving islet function, and reducing toxic immunosuppression.