Stem cell therapies for Type 1 diabetes: current status and proposed road map to guide successful clinical trials.

Many people with Type 1 diabetes struggle with the burden of self-management and are unable to achieve optimal glycaemic control without risk of hypoglycaemia. Future therapies with the potential to reduce the risk for short- and long-term complications while simultaneously reducing the burden of diabetes are therefore attractive. ß-cell replacement is one strategy which might achieve this. Islet transplantation is limited by organ supply and the risks of long-term immunosuppression. Encapsulated stem-cell-derived ß cells have the potential to address both of these issues and phase I/II clinical trials of encapsulated pancreatic progenitors have begun. A significant risk associated with the translation of stem-cell science to the clinical management of Type 1 diabetes is an underestimation of the complexity of the process and a mismatch between the hype and the expectations of both people with Type 1 diabetes and the public. We provide an update on progress in clinical trials of encapsulated stem-cell-derived ß cells and propose a road map for the design and conduct of future trials to facilitate the translation of this exciting science to clinical care.

Sitagliptin plus pantoprazole can restore but not maintain insulin independence after clinical islet transplantation: results of a pilot study.

AIMS: Resuming insulin use due to waning function is common after islet transplantation. Animal studies suggest that gastrointestinal hormones, including gastrin and incretins may increase ß-cell mass. We tested the hypothesis that pantoprazole plus sitagliptin, would restore insulin independence in islet transplant recipients with early graft insufficiency and determined whether this would persist after a 3-month washout. METHODS: Single-centre, uncontrolled, open label study of sitagliptin 100 mg daily plus pantoprazole 40 mg twice daily for 6 months. RESULTS: After 6 months of treatment, two of eight participants (25%) achieved the primary endpoint, defined as HbA1C < 42 mmol/mol (6%), fasting plasma glucose < 7.0 mmol, C-peptide > 0.5 nmol and no insulin use. There was a significant reduction in mean insulin dose, but no change in HbA1C or weight. There were no changes in the acute insulin response to arginine, the mixed meal tolerance test or blinded continuous glucose monitoring. After the washout, no participants met the primary endpoint and HbA1C increased from 45 ± 8 mmol/mol (6.3 ± 0.7%) to 51 ± 6 mmol/mol (6.8 ± 0.6%) (P < 0.05). Two participants had mild-moderate transient gastrointestinal side effects. There were no episodes of hypoglycaemia. CONCLUSIONS: Sitagliptin plus pantoprazole is well tolerated and safe and may restore insulin independence in some islet transplant recipients with early graft insufficiency, but this was not sustained when treatment was withdrawn. A larger, controlled trial is required to confirm the effectiveness of this combination to achieve insulin independence and to confidently exclude any persistent benefit for graft function. (Clinical Trials Registry No.: NCT00768651).

Validation of the BETA-2 Score: An Improved Tool to Estimate Beta Cell Function After Clinical Islet Transplantation Using a Single Fasting Blood Sample.

The beta score, a composite measure of beta cell function after islet transplantation, has limited sensitivity because of its categorical nature and requires a mixed-meal tolerance test (MMTT). We developed a novel score based on a single fasting blood sample. The BETA-2 score used stepwise forward linear regression incorporating glucose (in millimoles per liter), C-peptide (in nanomoles per liter), hemoglobin A1c (as a percentage) and insulin dose (U/kg per day) as continuous variables from the original beta score data set (n = 183 MMTTs). Primary and secondary analyses assessed the score's ability to detect glucose intolerance (90-min MMTT glucose ≥8 mmol/L) and insulin independence, respectively. A validation cohort of islet transplant recipients (n = 114 MMTTs) examined 12 mo after transplantation was used to compare the score's ability to detect these outcomes. The BETA-2 score was expressed as follows (range 0-42): [Formula: see text] A score <20 and ≥15 detected glucose intolerance and insulin independence, respectively, with >82% sensitivity and specificity. The BETA-2 score demonstrated greater discrimination than the beta score for these outcomes (p < 0.05). Using a fasting blood sample, the BETA-2 score estimates graft function as a continuous variable and shows greater discrimination of glucose intolerance and insulin independence after transplantation versus the beta score, allowing frequent assessments of graft function. Studies examining its utility to track long-term graft function are required.

Cardiovascular safety of sulphonylureas: over 40 years of continuous controversy without an answer.

More than 40 years after publication of the University Group Diabetes Program trial, the cardiovascular safety of sulphonylureas is still contentious. Although several hypotheses linking sulphonylureas to adverse cardiovascular effects exist, none provide conclusive evidence. Adding to the controversy, current clinical trials and observational studies provide inconsistent, and sometimes conflicting, evidence for the cardiovascular effects of sulphonylureas. Overall, observational evidence suggests that an increased risk of adverse cardiovascular outcomes is associated with sulphonylureas; however, these data may be subject to residual confounding and bias. Although evidence from randomized controlled trials has suggested a neutral effect, the majority of these studies were not specifically designed to assess the effect of sulphonylureas on adverse cardiovascular event risk. Current ongoing large clinical trials may provide some clarity on the cardiovascular safety of sulphonylureas, but the results are not expected for several years. With the continued uncertainties concerning the cardiovascular safety of all antidiabetic drugs, a clear answer with regard to sulphonylureas is warranted. The objectives of the present article were to provide an overview of the controversy surrounding sulphonylurea-related cardiovascular effects, to discuss the limitations of the current literature, and to provide recommendations for future studies aiming to elucidate the true relationship between sulphonylureas and adverse cardiovascular effects in people with type 2 diabetes.

A practical, clinical approach to the assessment and management of suspected insulin allergy.

BACKGROUND: Although allergic reactions to insulin are uncommon, they can be difficult to diagnose and management may be very difficult in subjects with Type 1 diabetes with severe allergy. Access to allergists and specialist diagnostic tests is limited and few diabetes specialists are familiar with desensitization as a means of treating allergy. People with diabetes may develop symptoms which mimic insulin allergy but are attributable to other conditions. CASE REPORTS: Here we describe three cases of insulin allergy. One patient presented with severe, albeit localized, urticarial reactions at injection sites. The most severe case was a woman with recent-onset Type 1 diabetes who presented with grade 2 anaphylaxis. The third patient presented with generalized urticaria and angioedema. Insulin allergy was confirmed in all three cases. METHODS: Assessment involved measurement of immunoglobulin and anti-insulin antibody levels. Skin testing was performed in two cases. Treatments included desensitization in one case, alternative insulin preparations, antihistamines and continuous subcutaneous insulin infusion. In all three cases of insulin allergy there has been successful resolution of symptoms. CONCLUSIONS: The clinical assessment and investigation in cases of suspected insulin allergy is described, along with detailed algorithms for skin testing and desensitization. This case series demonstrates an approach to challenging cases of suspected insulin allergy which will be helpful for diabetes specialists.

Three cases of alopecia following clinical islet transplantation.

Successful clinical islet allotransplantation requires control of both allo- and autoimmunity by using immunosuppressant drugs which have a number of side effects. The development of the autoimmune condition alopecia areata following successful islet transplantation is therefore unexpected. Three cases of alopecia affecting female islet transplant recipients are described. In all cases, alopecia developed approximately 7 years after initial transplant. All had received daclizumab, sirolimus and tacrolimus with their initial transplants, but all were receiving a combination of tacrolimus and mycophenolate mofetil at the time alopecia developed. Two subjects had received thymoglobulin for a subsequent islet infusion and prior to the onset of alopecia. The progression of alopecia has been halted or reversed in all cases. Tacrolimus has been continued in two cases (one as monotherapy) while cyclosporine was used in place of tacrolimus in the third case. These three cases represent a crude incidence of <2.5% over 5 years compared with a prevalence of alopecia in islet transplant candidates (pretransplant) of <1%. Although alopecia might be expected in a proportion of individuals with type 1 diabetes, the risk may be increased after islet transplantation, and may be associated with the use of anti-TNF drugs, lymphodepleting antibodies or higher dose tacrolimus.

Late cytomegalovirus transmission and impact of T-depletion in clinical islet transplantation.

The epidemiology of cytomegalovirus infection (CMV) in islet transplantation (IT) is not well defined. This study defines incidence, transmission and clinical sequelae of CMV reactivation or disease in 121 patients receiving 266 islet infusions at a single institution. The donor (D)/recipient (R) serostatus was D+/R- 31.2%, D+/R+ 26.3%, D-/R+ 13.2% and D-/R- 29.3%. CMV prophylaxis with oral ganciclovir/valganciclovir was given in 68%. CMV infection occurred in 14/121 patients (11.6%); six had asymptomatic seroconversion and eight others had positive viremia (six asymptomatic and two with CMV febrile symptoms). Median peak viral loads were 1755 copies/mL (range 625-9 100 000). Risk factors for viremia included lymphocyte depletion (thymoglobulin or alemtuzumab, p < 0.001). Viremia was more common in D+/R+ versus D+/R- (p = 0.12), occurring mostly late after transplant (median 306 days). Presumed transmission from IT occurred in 8/83 of D+/R- procedures (9.6%). Of the two cases of CMV disease, one resulted from islet transmission from a CMV positive donor (D+/R-); the other was due to de novo exogenous infection (D-/R-). Therefore, CMV transmission presents rarely after IT and with low incidence compared to solid organ transplantation, but occurs late posttransplant. The use of lymphocyte depleting therapies is a primary risk factor.

Portal vein thrombosis is a potentially preventable complication in clinical islet transplantation.

Percutaneous transhepatic portal access avoids surgery but is rarely associated with bleeding or portal venous thrombosis (PVT). We herein report our large, single-center experience of percutaneous islet implantation and evaluate risk factors of PVT and graft function. Prospective data were collected on 268 intraportal islet transplants (122 subjects). A portal venous Doppler ultrasound was obtained on Days 1 and 7 posttransplant. Therapeutic heparinization, complete ablation of the portal catheter tract with Avitene paste and limiting packed cell volume (PCV) to <5 mL completely prevented any portal thrombosis in the most recent 101 islet transplant procedures over the past 5 years. In the previous cumulative experience, partial thrombosis did not affect islet function. Standard liver volume correlated negatively (r =-0.257, p < 0.001) and PCV correlated positively with portal pressure rise (r = 0.463, p < 0.001). Overall, partial portal thrombosis occurred after 10 procedures (overall incidence 3.7%, most recent 101 patient incidence 0%). There were no cases of complete thrombosis and no patient developed sequelae of portal hypertension. In conclusion, portal thrombosis is a preventable complication in clinical islet transplantation, provided therapeutic anticoagulation is maintained and PCV is limited to <5 mL.

Short report: suboptimal diabetes care in high-risk diabetic patients attending a specialist retina clinic.

AIMS: Individuals with diabetic retinopathy (DR) represent a high-risk group who would benefit from intensive metabolic control and risk factor management. This brief report examines quality of care among diabetic patients attending a tertiary retinal clinic. METHODS: A cross-sectional survey, notes review, and slit-lamp examination was conducted in 139 diabetic patients attending a specialist retinal clinic to assess the quality of comprehensive diabetes care. DR was graded according to the Early Treatment Diabetic Retinopathy Study scale. RESULTS: The prevalence of non-proliferative DR (NPDR) and proliferative DR (PDR) was 39.6 and 35.2%, respectively. The prevalence of microalbuminuria in patients with no DR, NPDR and PDR was 32, 54.1 and 68.8%, respectively. Glycaemic control was suboptimal (mean HbA(1c) 8.0 +/- 1.8%) and 15.8% were current smokers. Drugs affecting the renin-angiotensin system were used by only 61.9% of patients with both DR and microalbuminuria, and aspirin by only 35.3%. CONCLUSIONS: These data suggest that diabetes care in this high-risk population with established microvascular complications was suboptimal. Specialist clinics dealing with diabetic complications may be a setting where quality improvement strategies to reduce morbidity and mortality should be focused.

Vitamin D status, body composition and glycemic control in an ambulatory population with diabetes and chronic kidney disease.

BACKGROUND/OBJECTIVES: To determine the interrelationships between body composition, glycemic control and vitamin D status in an ambulatory population with diabetes (DM) and chronic kidney disease (CKD). SUBJECTS/METHODS: Adult (18-80 years) patients (n=60) with DM and stage 1-4 CKD were recruited from the Northern Alberta Renal Program. Outcome variables included body composition (absolute/regional fat (FM)/lean soft tissue/total mass, percent fat/lean/fat-free (FFM) mass), glycemic control (glycated hemoglobin (HbA1c)), vitamin D intake (dietary/supplemental) and vitamin D status (25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)2D)) measured by validated methodologies. Sarcopenia was determined as an appendicular skeletal mass/height(2) less than 7.26 kg/m(2) (males) and 5.45 kg/m(2) (females). RESULTS: Suboptimal HbA1c (>7%), 25(OH)D (<50 nmol/l) and 1,25(OH)2D (<43 pmol/l) concentrations were present in 57, 8 and 11% of participants. Ten percent of subjects had sarcopenia. Gender/age/DM type, not CKD, significantly influenced regional/whole body composition. Females, older participants and those with type 2 DM had higher %FM. No significant interrelationships between vitamin D status and glycemic control were observed (P>0.05). Serum 25(OH)D concentrations were inversely associated with arm lean soft tissue/FFM/total mass, weight, appendicular skeletal mass, lean soft tissue/height(2), FFM/height(2), appendicular skeletal mass/height(2) and body mass index (P<0.05). Sarcopenia occurred more frequently in patients with 25(OH)D concentrations ⩾100 nmol/l. Regional/whole body %FM was inversely related to 1,25(OH)2D, not 25(OH)D. CONCLUSIONS: Body composition, not glycemic control, is associated with vitamin D status in an ambulatory population of adults with DM and CKD.

Dysregulation of PMN antigen expression in Type 2 diabetes may reflect a generalized defect of exocytosis: influence of hypertension and microalbuminuria.

Defective exocytosis could underlie clinical and metabolic abnormalities in Type 2 diabetes. Because many SNARE proteins appear to be common mediators of exocytosis, we examined phorbol myristate acetate-stimulated expression of CD11b and CD69 on polymorphonuclear leukocytes (PMN) from Type 2 diabetic subjects with hypertension and microalbuminuria (D-htma), hypertension only (D-ht) or uncomplicated (D-uc), and normal controls (NC) by flow cytometry. CD11b expression was rapid (half maximal by 7 min), initially on all PMN. CD69 expression took place subsequently but on PMN that did not express CD11b. The proportion of CD11b-positive PMN at 30 min was higher in all diabetic groups than in NC. Expression of CD11b was higher and CD69 lower in D-uc and D-htma but were similar in NC and D-ht. In Type 2 diabetes the transition from the CD11b-positive to CD69-positive state is impaired. The defect in the process of CD69 expression appeared most marked in diabetic subjects with hypertension and microalbuminuria.

Ethnicity as a variable in epidemiological research.

Ethnicity is used increasingly as a key variable to describe health data, and ethnic monitoring in the NHS will further stimulate this trend. We identify four fundamental problems with ethnicity in this type of research: the difficulties of measurement, the heterogeneity of the populations being studied, lack of clarity about the research purpose of the research, and ethnocentricity affecting the interpretation and use of data. Ethnicity needs to be used carefully to be a useful tool for health research. We make nine recommendations for future practice, one of which is that ethnicity and race should be recognised and treated as distinct concepts.

Changes in renal function after clinical islet transplantation: four-year observational study.

Tight glycemic control can reduce progression of diabetic nephropathy (DN) while the histological changes may regress after pancreas transplantation. Clinical islet transplantation (CIT) can restore euglycemia but the effects of CIT and concomitant immunosuppression on renal function are not known. Renal function (modification of diet in renal disease estimated glomerular filtration rate [GFR]) is reported in 41 type 1 diabetes subjects followed for 29.8 (6-57) months after CIT who received sirolimus and tacrolimus. HbA(1c) improved by 3 months (6.1 +/- 0.5 vs. 8.1 +/- 1.3%, p < 0.001) and was sustained. Over 4 years estimated GFR (eGFR) declined (repeated measures ANOVA: p = 0.0011). The median rate of change in eGFR was -0.39 mL/min/1.73 m(2)/month but was highly variable (range: +1.62 to -2.79 mL/min/1.73 m(2)/month). Progression of albuminuria was observed in ten individuals while regression of microalbuminuria was observed in only one (chi square = 22.51, df = 4, p = 0.0002). Despite improved glycemia, CIT and concomitant immunosuppression, was associated with a fall in eGFR and progression of albuminuria over 4 years of observation. The rate of decline in eGFR was extremely variable and difficult to predict. The risk of progressive nephrotoxicity with decline in eGFR should be discussed with prospective CIT candidates and the risk: benefit ratio carefully considered in individuals with pre-existing renal impairment.

Prevalence of autoimmune diseases in islet transplant candidates with severe hypoglycaemia and glycaemic lability: previously undiagnosed coeliac and autoimmune thyroid disease is identified by screening.

AIMS: Autoimmune diseases such as Addison's or coeliac disease can contribute to hypoglycaemia or malabsorption and are more common in Type 1 diabetes (T1DM). This brief report describes the prevalence of known and newly detected autoimmune disease in clinical islet transplant candidates with longstanding T1DM and severe hypoglycaemia and/or glycaemic lability who are routinely screened for coexisting autoimmune disease. METHODS: One hundred and twenty-four C-peptide negative T1DM subjects [77 (62%) female, mean age 44 +/- 9 years, diabetes duration 28 +/- 11 years, body mass index 24.9 +/- 3.5 kg/m(2)] with indications for clinical islet transplantation at the University of Alberta were screened for autoimmune disease by history and measurement of anti-transglutaminase antibodies (positive > 10 U/ml), 09.00 h cortisol (followed by adrenocorticotrophic hormone-stimulation if < 495 nmol/l) and thyroid-stimulating hormone to determine the prevalence of coeliac disease, Addison's disease and autoimmune thyroid disease, respectively. RESULTS: Forty per cent of subjects had one or more coexisting autoimmune disease. The prevalence of autoimmune disease was 35%, coeliac disease 8% and Addison's disease 1.6%. In 11 individuals (9%), one or more autoimmune disease were newly detected (seven coeliac disease and five thyroid disease). Seven of 10 cases of coeliac disease were newly detected. A gluten-free diet in individuals with newly diagnosed coeliac disease reduced gastrointestinal symptoms, but indications for clinical islet cell transplantation persisted. CONCLUSIONS: Coexisting autoimmune disease is common in candidates for clinical islet cell transplantation. Screening in this group identified a substantial number of previously unrecognized cases. Clinicians should consider the presence of autoimmune disease even in the absence of classical symptoms.

High risk of sensitization after failed islet transplantation.

Human Leukocyte Antigen (HLA) antibodies posttransplant have been associated with an increased risk of early graft failure in kidney transplants. Whether this also applies to islet transplantation is not clear. To achieve insulin independence after islet transplants multiple donor infusions may be required. Hence, islet transplant recipients are at risk of sensitization after transplantation. Islet transplant recipients were screened for HLA antibodies posttransplant by flow-based methods. A total of 98 patients were studied. Twenty-nine patients (31%) developed de novo donor specific antibodies (DSA) posttransplant. Twenty-three patients developed DSA while on immunosuppression (IS). Among recipients who have discontinued IS, 10/14 (71%) are broadly sensitized with panel reactive antibody (PRA) >or=50%. The risk of becoming broadly sensitized after transplant was 11/69 (16%) if the recipient was unsensitized prior to transplant. The majority of these antibodies have persisted over time. Appearance of HLA antibodies posttransplant is concerning, and the incidence rises abruptly in subjects weaned completely from IS. This may negatively impact the ability of these individuals to undergo further islet, pancreas or kidney transplantation and should be discussed upfront during evaluation of candidates for islet transplantation.

Abnormal thiol group modulation of sodium-lithium countertransport and membrane fluidity is associated with a disturbed relationship between serum triacylglycerols and membrane function in type II diabetes.

In essential hypertension and diabetic nephropathy, sodium-lithium countertransport (Na-Li CT) is an inherited marker, subject to metabolic influences, of cardiovascular risk. Studies in Type II diabetes, taking clinical phenotypes as their starting point, are conflicting. We sought to identify Na-Li CT kinetic abnormalities in Type II diabetes, and only subsequently to seek relationships with clinical variables. Na-Li CT kinetics, membrane fluidity and their modulation by thiol proteins were measured in erythrocytes from 38 patients with Type II diabetes and in 16 normal control subjects. In untreated erythrocytes, Na-Li CT kinetics were similar. Thiol protein alkylation with N-ethylmaleimide generally caused both V(max) and K(m) to fall, but caused K(m) to rise in erythrocytes from 13 out of 38 diabetic subjects, whose native K(m) was low (P=0. 0013 compared with control). V(max) and serum triacylglycerol levels were related in normal controls (r(s)=0.54, P=0.038) and in diabetic subjects whose K(m) fell after N-ethylmaleimide (n=25, r(s)=0.62, P=0.001). Where the K(m) rose after N-ethylmaleimide, V(max) and triacylglycerol levels were not related (n=13, r(s)=-0.39, P=0.183) and membrane fluidity did not increase after N-ethylmaleimide. However, these subgroups were indistinguishable in terms of blood pressure, albuminuria, glycaemia or lipid profiles. Thus abnormalities in the regulation of Na-Li CT and membrane fluidity by key thiol proteins, resembling those seen in essential hypertension and diabetic nephropathy, were apparent in one-third of subjects with Type II diabetes. Membrane abnormalities may indicate a common pathological mechanism. The prognostic significance of Na-Li CT kinetic abnormalities in Type II diabetes must now be confirmed.