C-peptide Secretion Research Articles

Effective endothelial cell and human pluripotent stem cell interactions generate functional insulin-producing beta cells.

Aims/hypothesisEndothelial cells (ECs) play an essential role in pancreatic organogenesis. We hypothesise that effective in vitro interactions between human microvascular endothelial cells (HMECs) and human pluripotent stem cells (hPSCs) results in the generation of functional pancreatic beta cells.MethodsEmbryoid bodies (EBs) derived from hPSCs were cultured alone (controls) or with ECs in collagen gels. Subsequently, cells were analysed for pancreatic beta cell markers, and then isolated and expanded. Insulin secretion in response to glucose was evaluated in vitro by static and dynamic (perifusion) assays, and in vivo by EB transplantation into immunodeficient mice.ResultsCo-cultured EBs had a higher expression of mature beta cells markers and enhanced insulin secretion in vitro, compared with controls. In mice, transplanted EBs had higher levels of human C-peptide secretion with a significant reduction in hyperglycaemia after the selective destruction of native pancreatic beta cells. In addition, there was significant in vitro upregulation of bone morphogenetic proteins 2 and 4 (BMP-2, 4) in co-cultured cells, compared with controls.Conclusions/interpretationECs provide essential signalling in vitro, such as activation of the BMP pathway, for derivation of functional insulin-producing beta cells from hPSCs.Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-016-4078-1) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

The clinical potential of low-level C-peptide secretion

ABSTRACTIntroduction: In all forms of diabetes, especially so in Type 1 diabetes (T1D), beta cell function is crucial for the course. The interest for residual beta cell function has been meagre, but increased in recent years with interventions to preserve function.Areas covered: Importance and clinical use of C-peptide in Type 1 diabetes. Data for this review were identified by searches of PubMed, and references from relevant articles using the search terms: “type 1 diabetes”, “C-peptide”, “beta cell function”, “HbA1c”, quality of life”, “complications”. s and reports from meetings were not included.Expert commentary: C-peptide may help to get a correct diagnosis, and it is of practical clinical value to know degree of residual insulin secretion to diminish the risk of severe hypoglycaemia and ketoacidosis. Evidence shows that even a quite reduced beta cell function may play an important role for quality of life, for metabolic balance/control, possibility to avoid complications and even for long-term survival. Furthermore, the evidence is increasing for C-peptide being a hormone per se.

Fall in C-Peptide During First 4 Years From Diagnosis of Type 1 Diabetes: Variable Relation to Age, HbA1c, and Insulin Dose.

OBJECTIVEWe aimed to describe the natural history of residual insulin secretion in Type 1 Diabetes TrialNet participants over 4 years from diagnosis and relate this to previously reported alternative clinical measures reflecting β-cell secretory function.RESEARCH DESIGN AND METHODSData from 407 subjects from 5 TrialNet intervention studies were analyzed. All subjects had baseline stimulated C-peptide values of ≥0.2 nmol/L from mixed-meal tolerance tests (MMTTs). During semiannual visits, C-peptide values from MMTTs, HbA1c, and insulin doses were obtained.RESULTSThe percentage of individuals with stimulated C-peptide of ≥0.2 nmol/L or detectable C-peptide of ≥0.017 nmol/L continued to diminish over 4 years; this was markedly influenced by age. At 4 years, only 5% maintained their baseline C-peptide secretion. The expected inverse relationships between C-peptide and HbA1c or insulin doses varied over time and with age. Combined clinical variables, such as insulin-dose adjusted HbA1c (IDAA1C) and the relationship of IDAA1C to C-peptide, also were influenced by age and time from diagnosis. Models using these clinical measures did not fully predict C-peptide responses. IDAA1C ≤9 underestimated the number of individuals with stimulated C-peptide ≥0.2 nmol/L, especially in children.CONCLUSIONSCurrent trials of disease-modifying therapy for type 1 diabetes should continue to use C-peptide as a primary end point of β-cell secretory function. Longer duration of follow-up is likely to provide stronger evidence of the effect of disease-modifying therapy on preservation of β-cell function.

Insulin Plays a Permissive Role for the Vasoactive Effect of GIP Regulating Adipose Tissue Metabolism in Humans.

Glucose-dependent insulinotropic polypeptide (GIP) in combination with hyperinsulinemia increases blood flow and triglyceride (TAG) clearance in subcutaneous (sc) abdominal adipose tissue in lean humans. The present experiments were performed to further investigate the role of insulin for the vasoactive effect of GIP in adipose tissue metabolism and whether the vasodilatory effect of GIP is dependent on C-peptide. Six lean healthy subjects were studied. The sc abdominal adipose tissue metabolism was assessed by Fick's principle during GIP infusion (1.5 pmol/kg/min) in combination with 1) euglycemic-high insulinemic clamp (Eugluc-Hiinsu), raising plasma insulin concentrations to postprandial levels, 2) hyperglycemic-euinsulinemic clamp (Hygluc-Euinsu), and 3) hyperglycemic-hyperinsulinemic clamp, raising plasma insulin concentrations to supraphysiological levels. During the hyperglycemic clamps, endogenous insulin and C-peptide secretion were inhibited by infusion of the somatostatin analogue octreotide. During GIP infusion, Eugluc-Hiinsu, and hyperglycemic-hyperinsulinemic clamps, sc abdominal adipose tissue blood flow (ATBF) was similar and increased from 2.1 ± 0.2 and 2.2 ± 0.4 ml min(-1) (100 g tissue)(-1) to 7.1 ± 0.6 and 7.6 ± 0.1 ml min(-1) (100 g tissue)(-1), respectively (P < .01). ATBF remained virtually constant (2.7 ± 0.4 ml min(-1) [100 g tissue](-1)) during Hygluc-Euinsu and GIP infusion. In addition, adipose tissue TAG clearance increased significantly (P = .03), whereas free fatty acid output (P = .01), glycerol output (P = .02) and free fatty acid/glycerol release ratio (P = .04) decreased during the Eugluc-Hiinsu clamp compared to Hygluc-Euinsu clamp with GIP. In healthy lean humans, insulin is permissive for GIP to induce an increase in blood flow and TAG clearance in sc abdominal adipose tissue. This effect is independent of C-peptide.

117 - C-Peptide Secretion of Engineered Human Pancreatic Like Islets Obtained From Adipose MSC Cultured on an Acellular Matrix in Presence of Activated Effector Cells

Introduction: In ISCT meeting of 2012 (Netherland) was reported morphologic successful production of engineered pancreatic like islets. It was done using human adipose Mesenchymal Stroma Cells (MSC), growing on swine cell free pancreatic islet matrix (PIM) and co cultured with anti pancreatic islet effector T cells (ETC). Peroxidase immune stains showed change in MSC phenotype that become Insulin and Glucagon producing cells. This reports study the functionality of these Pancreatic like Islets.

Correlation Among Hypoglycemia, Glycemic Variability, and C-Peptide Preservation After Alefacept Therapy in Patients with Type 1 Diabetes Mellitus: Analysis of Data from the Immune Tolerance Network T1DAL Trial

PurposeIn natural history studies, maintenance of higher levels of C-peptide secretion (a measure of endogenous insulin production) correlates with a lower incidence of major hypoglycemic events in patients with type 1 diabetes mellitus (T1D), but it is unclear whether this is also true for drug-induced C-peptide preservation. MethodsWe analyzed hypoglycemic events and glycemic control data from the T1DAL (Inducing Remission in New-Onset T1D with Alefacept) study, a trial of alefacept in new-onset T1D, which found significant C-peptide preservation at 1 and 2 years. We performed a post hoc analysis using mixed models of the association between the meal-stimulated 4-hour C-peptide AUC (4-hour AUC) and rates of major hypoglycemia, measures of glycemic control (glycosylated hemoglobin [HbA1c]; mean glucometer readings), and variability (glucometer SDs; highest and lowest readings), and an index of partial remission (insulin dose-adjusted HbA1c[ IDAA1c]). FindingsData from 49 participants (33 in the alefacept group and 16 in the placebo group) were analyzed at baseline and 12 and 24 months. We found that the 4-hour AUC at baseline and at 1 year was a significant predictor of the number of hypoglycemic events during the ensuing 12-month interval (p = 0.030). There was a strong association between the 4-hour AUC and glucometer SDs (P < 0.001), highest readings (p < 0.001), and lowest readings (p = 0.03), all measures of glycemic variability. There was a strong inverse correlation between the 4-hour AUC and 2 measures of glycemic control: HbA1c and mean glucometer readings (both p < 0.001). There was also a strong inverse correlation between the 4-hour AUC and IDAA1c values (p < 0.001), as well as a strong correlation between IDAA1c values and glucometer SDs (p < 0.001), suggesting that reduced glycemic variability is associated with a trend toward partial remission. None of these analyses found a significant difference between the alefacept and placebo groups. ImplicationsMeasures of glycemic variability and control, including rates of hypoglycemia, are significantly correlated with preservation of C-peptide regardless of whether this is achieved by immune intervention with alefacept or natural variability in patients with new-onset T1D. Thus, preservation of endogenous insulin production by an immunomodulatory drug may confer clinical benefits similar to those seen in patients with higher C-peptide secretion due to slow disease progression.

Antithymocyte globulin therapy for patients with recent-onset type 1 diabetes: 2year results of a randomised trial.

Aims/hypothesisType 1 diabetes results from T cell mediated destruction of beta cells. We conducted a trial of antithymocyte globulin (ATG) in new-onset type 1 diabetes (the Study of Thymoglobulin to ARrest T1D [START] trial). Our goal was to evaluate the longer-term safety and efficacy of ATG in preserving islet function at 2 years.MethodsA multicentre, randomised, double-blind, placebo-controlled trial of 6.5 mg/kg ATG (Thymoglobulin) vs placebo in patients with new-onset type 1 diabetes was conducted at seven university medical centres and one Children’s Hospital in the USA. The site-stratified randomisation scheme was computer generated at the data coordinating centre using permuted-blocks of size 3 or 6. Eligible participants were between the ages of 12 and 35, and enrolled within 100 days from diagnosis. Subjects were randomised to 6.5 mg/kg ATG (thymoglobulin) vs placebo in a 2:1 ratio. Participants were blinded, and the study design included two sequential patient-care teams: an unblinded study-drug administration team (for the first 8 weeks), and a blinded diabetes management team (for the remainder of the study). Endpoints assessed at 24 months included meal-stimulated C-peptide AUC, safety and immunological responses.ResultsFifty-eight patients were enrolled; at 2 years, 35 assigned to ATG and 16 to placebo completed the study. The pre-specified endpoints were not met. In post hoc analyses, older patients (age 22–35 years) in the ATG group had significantly greater C-peptide AUCs at 24 months than placebo patients. Using complete preservation of baseline C-peptide at 24 months as threshold, nine of 35 ATG-treated participants (vs 2/16 placebo participants) were classified as responders; nine of 11 responders (67%) were older. All participants reported at least one adverse event (AE), with 1,148 events in the 38 ATG participants vs 415 in the 20 placebo participants; a comparable number of infections were noted in the ATG and placebo groups, with no opportunistic infections nor difficulty clearing infections in either group. Circulating T cell subsets depleted by ATG partially reconstituted, but regulatory, naive and central memory subsets remained significantly depleted at 24 months. Beta cell autoantibodies did not change over the 24 months in the ATG-treated or placebo participants. At 12 months, ATG-treated participants had similar humoral immune responses to tetanus and HepA vaccines as placebo-treated participants, and no increased infections.Conclusions/interpretationA brief course of ATG substantially depleted T cell subsets, including regulatory cells, but did not preserve islet function 24 months later in the majority of patients with new-onset type 1 diabetes. ATG preserved C-peptide secretion in older participants, which may warrant further study.Trial registration:ClinicalTrials.gov NCT00515099Public data repository:START datasets are available in TrialShare www.itntrialshare.org Funding:National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health (NIH). The trial was conducted by the Immune Tolerance Network (ITN).Electronic supplementary materialThe online version of this article (doi:10.1007/s00125-016-3917-4) contains peer-reviewed but unedited supplementary material, which is available to authorised users.

Expanding the indications for pancreas resection and autologous islet cell transplantation (IAT) in both adults and children

Introduction: Pancreas resection combined with IAT is a controversial procedure with limited experience in the UK and is not funded by the NHS. We present our experience of IAT in patients with chronic pancreatitis and pancreatic trauma including the UK's first paediatric transplant. Methods: We have performed 6 pancreatic resections with IAT over 18 months. 3 patients with chronic pancreatitis (2 hereditary, 1 idiopathic) have undergone total pancreatectomy and IAT. Two patients had previous Frey procedures. 3 patients (2 adults, 1 child) sustained blunt pancreatic trauma and underwent extended left pancreatectomy combined with IAT. Complications were graded according to the Clavien-Dindo classification. Results: In the chronic pancreatitis group the islet yield was low due to fibrosis /previous drainage procedures (<50,000 IEQ). The first patient is now opiate independent and the remaining 2 patients continue on reducing doses. All have marked improvement in their quality of life. All require low dose insulin analogue therapy with in vivo C-peptide secretion. In contrast the trauma patients had a much greater islet yield (99,750–298,149 IEQ). All are insulin independent. There were no complications related to portal vein infusion and no deaths, one patient required re-laparotomy for an infected collection. Conclusions: Pancreatectomy and IAT can be used as a salvage procedure in patients who have failed all other therapy but in our opinion results would be superior if performed earlier in the course of their disease. It is also a feasible management option for complex pancreatic trauma in both adults and children.

Transient Suppression of TGFβ Receptor Signaling Facilitates Human Islet Transplantation.

Although islet transplantation is an effective treatment for severe diabetes, its broad application is greatly limited due to a shortage of donor islets. Suppression of TGFβ receptor signaling in β-cells has been shown to increase β-cell proliferation in mice, but has not been rigorously examined in humans. Here, treatment of human islets with a TGFβ receptor I inhibitor, SB-431542 (SB), significantly improved C-peptide secretion by β-cells, and significantly increased β-cell number by increasing β-cell proliferation. In addition, SB increased cell-cycle activators and decreased cell-cycle suppressors in human β-cells. Transplantation of SB-treated human islets into diabetic immune-deficient mice resulted in significant improvement in blood glucose control, significantly higher serum and graft insulin content, and significantly greater increases in β-cell proliferation in the graft, compared with controls. Thus, our data suggest that transient suppression of TGFβ receptor signaling may improve the outcome of human islet transplantation, seemingly through increasing β-cell number and function.

Correction of Murine Diabetic Hyperglycaemia With A Single Systemic Administration of An AAV2/8 Vector Containing A Novel Codon Optimized Human Insulin Gene.

We report the correction of hyperglycemia of STZ induced diabetic mice using one intravenous systemic administration of a single stranded serotype 8 pseudotyped adeno-associated virus (ssAAV2/8) vector encoding the human proinsulin gene under a constitutive liver specific promoter. In vivo dose titration experiments were carried out and we identified an optimal range that achieved maintenance of euglycaemia or a mild diabetic condition for at least 9 months and ongoing to beyond 1 year for some animals, accompanied by human C-peptide secretion and weight gain. Further DNA codon optimization of the insulin gene construct resulted in approximately 3-10 times more human C-peptide secreted in the blood of codon optimized treated animals thereby reducing the number of vector particles required to achieve the same extent of reduction in blood glucose levels as the non-codon optimized vector. The constitutive secretion of insulin achieved with a single administration of the vector could be of therapeutic value for some diabetic patients.

The effect of oral and intravenous dextrose on C-peptide secretion in ponies.

Managing equine hyperinsulinemia is crucial for preventing laminitis, but our understanding of the mechanisms involved in insulin dysregulation in this species is incomplete. C-peptide is co-secreted with insulin but is resistant to hepatic metabolism and can be used to study insulin dysregulation. This study examined C-peptide secretion in serial blood samples collected after oral and i.v. dextrose (0.75 g/kg) administration to 9 ponies (BCS, 7.1 ± 0.5). The ponies were designated as hyperinsulinemic (HI) or normoinsulinemic (NI) responders before the study, using oral glucose tests and fasted glucose-to-insulin ratios, and responses were compared between the 2 groups. C-peptide concentrations increased ( < 0.01) rapidly from fasted levels after both oral and i.v. dextrose, with similar area under the concentration-time curve (AUC) for both tests and a significant correlation with AUC. The AUC was similar in HI and NI ponies after i.v. dextrose, indicating similar pancreatic capacity for both groups. However, for oral dextrose, the AUC and the AUC were markedly higher ( < 0.05) in the HI ponies, indicating a greater secretion rate of these peptides. Slower insulin clearance might have also contributed to the larger AUC in HI ponies, but this hypothesis requires further investigation with specific measures of hepatic insulin clearance.

Double diabetes in Saudi Arabia: A new entity or an underestimated condition.

AIMTo determine the clinical and biological characteristics of double diabetes (DD) among young people in Saudi Arabia.METHODSThis was a retrospective descriptive chart review study including 312 young newly diagnosed diabetic patients (aged 12-20 years), whom were admitted over a five year period (January 2009 to December 2013). Family history of diabetes mellitus (DM) (first degree), physical body mass index (BMI), acanthosis nigricans, history of auto-immune disease and laboratory information for glycosylated hemoglobin, basal C peptide level and diabetes autoantibody response (anti-GAD, anti-IA2 and anti-ICA) were collected from medical report. A mean follow-up of 3 years for these patients was performed.RESULTSPatients were categorized into 4 groups, based on the autoantibody response (Ab+ or Ab-) and C-peptide secretion (β+ for fasting level 0.4-2.1 ng/mL and β- if < 0.4 ng/mL). Group1 (type 1a): Ab+ β- (21%), group 2 (type 1b): Ab- β- (9%), group 3 (DD): Ab+ β+ (31%) and group 4 (classic type 2 DM): Ab- β+ (39%). The mean age of the DD patients in our study was 15.1 ± 6.4 years. A total of 41% of the study population presented with diabetic ketoacidosis and 61% of the study population presented with positive family history of DM. The mean BMI was 26.8 kg/m2 with 64% of overweight or obese patients. Ninety two percent of the patients were started on insulin at the time of diagnosis. During a mean follow-up of 3 years, only 32% of the patients with DD required insulin and 78% were on metformin alone or with insulin.CONCLUSIONOur findings enable us to arrive at the conclusion that almost one-third of the young Saudi diabetic patients reveal atypical forms of DM (double diabetes) expressing features resulting from both T1D and T2D.

Treg activation defect in type 1 diabetes: correction with TNFR2 agonism.

Activated T-regulatory cells (aTregs) prevent or halt various forms of autoimmunity. We show that type 1 diabetics (T1D) have a Treg activation defect through an increase in resting Tregs (rTregs, CD4+CD25+Foxp3+CD45RA) and decrease in aTregs (CD4+CD25+Foxp3+CD45RO) (n= 55 T1D, n=45 controls, P=0.01). The activation defect persists life long in T1D subjects (T1D=45, controls=45, P=0.01, P=0.04). Lower numbers of aTregs had clinical significance because they were associated with a trend for less residual C-peptide secretion from the pancreas (P=0.08), and poorer HbA1C control (P=0.03). In humans, the tumor necrosis factor receptor 2 (TNFR2) is obligatory for Treg induction, maintenance and expansion of aTregs. TNFR2 agonism is a method for stimulating Treg conversion from resting to activated. Using two separate in vitro expansion protocols, TNFR2 agonism corrected the T1D activation defect by triggering conversion of rTregs into aTregs (n=54 T1D, P<0.001). TNFR2 agonism was superior to standard protocols and TNF in proliferating Tregs. In T1D, TNFR2 agonist-expanded Tregs were homogeneous and functionally potent by virtue of suppressing autologous cytotoxic T cells in a dose-dependent manner comparable to controls. Targeting the TNFR2 receptor for Treg expansion in vitro demonstrates a means to correct the activation defect in T1D.

Glucose Effectiveness: The Mouse Trap in the Development of Novel ß-Cell Replacement Therapies.

Cure of diabetes and normalization of glucose disposal during intravenous glucose tolerance tests (IVGTT) remains critical for stringent evaluation of novel replacement therapies in type 1 diabetes. Glucose disposal during an IVGTT depends on a complex interaction of both insulin-dependent and -independent mechanisms. Glucose effectiveness, that is, the function of glucose per se, independent of insulin, to stimulate its uptake and suppress endogenous glucose production is less recognized. To unravel the relative importance of these pathways, rats were injected with streptozotocin to induce diabetes and implanted subcutaneously with slow-release devices of insulin. These animals demonstrated rapid normalization of blood glucose and perfectly normal glucose disposal during an IVGTT with no differences when compared with nondiabetic controls even though no active c-peptide secretion was detected in plasma and almost no remaining insulin-producing cells were present in the pancreas. The present study highlights that glucose is the predominant mediator of its own disposal in rodents having only basal and nonglucose-regulated plasma insulin levels. The herein presented results calls for a reassessment how results obtained in the most commonly used experimental models should be interpreted in the development of future replacement therapies in type 1 diabetes.

Glucagon secretion is increased in patients with Type 2 diabetic nephropathy

AimsCurrently little is known about the relationship between renal function, albuminuria and glucagon; we analyzed the secretion of glucagon (GLA) and C-peptide in Type 2 diabetic patients with different degrees of nephropathy. Methods357 patients with Type 2 diabetes including 119 cases without nephropathy and 238 cases with nephropathy were divided into four groups according to the stages of diabetic nephropathy. Patients with diabetic nephropathy were further classified according to the level of estimated glomerular filtration rate (eGFR). OGTT and insulin, C-peptide, glucagon releasing tests were performed in all patients. Characteristics of glucagon and C-peptide secretion in different groups were compared. Glucagon/glucose ratio (GLA/GLU) and glucagon/insulin ratio (GLA/INS) were used to represent the inhibition of glucose or insulin on glucagon secretion, respectively. ResultsWith the progress of diabetic nephropathy, glucagon level increased significantly; the glucagon peak after glucose load delayed from 60min to 120min, whereas C-peptide level decreased significantly. Related factors analysis suggested that glucagon was independently correlated with eGFR. Further analysis showed that glucagon level was higher in group with eGFR<60ml/min compared with that in group with eGFR≥60ml/min. In addition, both GLA/INS and GLA/GLU were higher in group with eGFR<60ml/min compared with those in group with eGFR≥60ml/min. ConclusionsPatients with Type 2 diabetic nephropathy have worsened islet alpha and beta cell function. Therefore medications based on the regulation of glucagon secretion may improve glycemic control and also be beneficial for delaying the progress of diabetic nephropathy.

Monitoring C-Peptide Storage and Secretion in Islet β-Cells In Vitro and In Vivo.

Human proinsulin with C-peptide–bearing Superfolder Green Fluorescent Protein (CpepSfGFP) has been expressed in transgenic mice, driven by the Ins1 promoter. The protein, expressed exclusively in β-cells, is processed and stored as CpepSfGFP and human insulin comprising only ∼0.04% of total islet proinsulin plus insulin, exerting no metabolic impact. The kinetics of the release of insulin and CpepSfGFP from isolated islets appear identical. Upon a single acute stimulatory challenge in vitro, fractional release of insulin does not detectably deplete islet fluorescence. In vivo, fluorescence imaging of the pancreatic surface allows, for the first time, visual assessment of pancreatic islet insulin content, and we demonstrate that CpepSfGFP visibly declines upon diabetes progression in live lepRdb/db mice. In anesthetized mice, after intragastric or intravenous saline delivery, pancreatic CpepSfGFP (insulin) content remains undiminished. Remarkably, however, within 20 min after acute intragastric or intravenous glucose delivery (with blood glucose concentrations reaching >15 mmol/L), a small subset of islets shows rapid dispossession of a major fraction of their stored CpepSfGFP (insulin) content, whereas most islets exhibit no demonstrable loss of CpepSfGFP (insulin). These studies strongly suggest that there are “first responder” islets to an in vivo glycemic challenge, which cannot be replicated by islets in vitro.

Accelerated Maturation of Human Stem Cell-Derived Pancreatic Progenitor Cells into Insulin-Secreting Cells in Immunodeficient Rats Relative to Mice.

SummaryPluripotent human embryonic stem cells (hESCs) are a potential source of transplantable cells for treating patients with diabetes. To investigate the impact of the host recipient on hESC-derived pancreatic progenitor cell maturation, cells were transplanted into immunodeficient SCID-beige mice or nude rats. Following the transplant, basal human C-peptide levels were consistently higher in mice compared with rats, but only rats showed robust meal- and glucose-responsive human C-peptide secretion by 19–21 weeks. Grafts from rats contained a higher proportion of insulin:glucagon immunoreactivity, fewer exocrine cells, and improved expression of mature β cell markers compared with mice. Moreover, ECM-related genes were enriched, the collagen network was denser, and blood vessels were more intricately integrated into the engrafted endocrine tissue in rats relative to mice. Overall, hESC-derived pancreatic progenitor cells matured faster in nude rats compared with SCID-beige mice, indicating that the host recipient can greatly influence the fate of immature pancreatic progenitor cells post-transplantation.

Clinical polymorphism of type 2 diabetes in children — the first study in Russia

Objective.To elucidate the specific features of diagnostics, clinical course and manifestations of type 2 diabetes mellitus (DM2) in the children of the Russian population.Material and methods.A total of 80 children presenting with DM2 were enrolled in the study including 70 available for the dynamic examination, with the follow-up period of 2.6 years (1.5; 4.5). The general clinical examination of the patients was supplemented by measuring insulin secretion, studying HLA-polymorphism of the DQ and DR-genes, and determination of type 1 diabetes (DM1) — related specific antibodies (At).Results.The median age at diagnosis of DM2 was 13 years (11.5; 15.5). 58.8% of the children had a family history of DM2 but only 26.3% of them had classical complaints of diabetes mellitus. In 65% of the children, DM2 was diagnosed when they were passing medical examination in connection with obesity (in 51.9% with the use the oral glucose tolerance test (OGTP); 48.1% of these children had the fasting blood glucose level above 7.0 mmol/l. Ketonuria at the onset of the disease was documented in 21.3% of the patients while 85% were either obese or overweight. Antibodies (ICA and IAA) were detected in 15.2% of the children at a low titer. The HLA-genotype associated with a high risk of development of DM1 was identified in 5.5% of the cases. The glycosylated hemoglobin test revealed its mean level of 7.1% (6.3; 8.5%) at the onset of diabetes; in the majority of the children, it fell down below 6.5% within the first 3 years of the disease. During this period, insulin and C-peptide secretion remained elevated. Insulin resistance was initially documented in 81.3% of the children; the dynamic observation failed to show its appreciable decrease. Insulin therapy initiated at the onset of the disease was prescribed to 30% of the patients. After 3 years, only 8% of the children retaining endogenous insulin secretion continued to use insulin.Conclusion.The asymptomatic onset of type 2 diabetes mellitus in the children and adolescents emphasizes the importance of its active diagnostics during the pubertal period in the high risk groups comprising the patients with obesity and the family history of DM2. In one third of the children, the diagnosis of DM2 was possible only with the use the oral glucose tolerance test. DM2 in the children and adolescents is characterized by clinical polymorphism in the form of acute manifestations in 21% of the cases and the absence of obesity and insulin resistance in 15 and 18% respectively. This finding suggests the necessity of differential diagnostics of such cases from DM1 and MODY. Rather high insulin and C-peptide secretion persists for 3 years after the onset of DM2 in the children. Therefore, they do not need insulin therapy during this period. The presence of ICA and IAA antibodies at low titers does not compromise diagnosis of DM2.

Post-glucose-load urinary C-peptide and glucose concentration obtained during OGTT do not affect oral minimal model-based plasma indices.

The purpose of this study was to investigate how renal loss of both C-peptide and glucose during oral glucose tolerance test (OGTT) relate to and affect plasma-derived oral minimal model (OMM) indices. All individuals were recruited during family screening between August 2007 and January 2011 and underwent a 3.5-h OGTT, collecting nine plasma samples and urine during OGTT. We obtained the following three subgroups: normoglycemic, at risk, and T2D. We recruited South Asian and Caucasian families, and we report separate analyses if differences occurred. Plasma glucose, insulin, and C-peptide concentrations were analyzed as AUCs during OGTT, OMM estimate of renal C-peptide secretion, and OMM beta-cell and insulin sensitivity indices were calculated to obtain disposition indices. Post-glucose load glucose and C-peptide in urine were measured and related to plasma-based indices. Urinary glucose corresponded well with plasma glucose AUC (Cau r = 0.64, P < 0.01; SA r = 0.69, P < 0.01), SI (Cau r = −0.51, P < 0.01; SA r = −0.41, P < 0.01), Φdynamic (Cau r = −0.41, P < 0.01; SA r = −0.57, P < 0.01), and Φoral (Cau r = −0.61, P < 0.01; SA r = −0.73, P < 0.01). Urinary C-peptide corresponded well to plasma C-peptide AUC (Cau r = 0.45, P < 0.01; SA r = 0.33, P < 0.05) and OMM estimate of renal C-peptide secretion (r = 0.42, P < 0.01). In general, glucose excretion plasma threshold for the presence of glucose in urine was ~10–10.5 mmol L−1 in non-T2D individuals, but not measurable in T2D individuals. Renal glucose secretion during OGTT did not influence OMM indices in general nor in T2D patients (renal clearance range 0–2.1 %, with median 0.2 % of plasma glucose AUC). C-indices of urinary glucose to detect various stages of glucose intolerance were excellent (Cau 0.83–0.98; SA 0.75–0.89). The limited role of renal glucose secretion validates the neglecting of urinary glucose secretion in kinetic models of glucose homeostasis using plasma glucose concentrations. Both C-peptide and glucose in urine collected during OGTT might be used as non-invasive measures for endogenous insulin secretion and glucose tolerance state.

Long-Term Immunosuppression After Solitary Islet Transplantation Is Associated With Preserved C-Peptide Secretion for More Than a Decade

We report on two patients with type 1 diabetes (T1D) after solitary islet transplantation in 2001. They received steroid-sparing immunosuppression (daclizumab, sirolimus, and tacrolimus according to the Edmonton protocol). Both patients became insulin independent for 2 years: Patient A, a 42-year-old female with a 12-year history of T1D, received two islet infusions; patient B, a 53-year-old female with a 40-year T1D history, received one islet infusion. Pretransplant, both had undetectable C-peptide concentrations and frequent and severe hypoglycemia. Pretransplant, hemoglobin A1c (HbA1c) was 7.8% and 8.8% and insulin requirements were 0.47 and 0.33 units/kg/day, respectively. Posttransplant, C-peptide levels remained detectable while immunosuppression was continued, but decreased over time. Insulin was re-started 2 years posttransplant in both patients. Since patient A's glycemia and insulin requirements trended toward pretransplant levels, immunosuppression was discontinued after 13 years. This resulted in a sudden cessation of C-peptide secretion. Patient B continues on immunosuppression, has better HbA1c, and half the insulin requirement compared to pretransplant. Both patients no longer experience severe hypoglycemia. Herein, we document blood glucose concentrations over time (>30 000 measurements per patient) and β cell function based on C-peptide secretion. Despite renewed insulin dependence, both patients express satisfaction with having undergone the procedure.