Ultrasound detection of insulin-induced lipohypertrophy in Type 1 and Type 2 diabetes

AIMS

To define standard criteria for the detection of lipohypertrophy using ultrasonography and to determine the accuracy of this method.

METHOD

Individuals using insulin therapy for ≥2 years with unknown lipohypertrophy status were enrolled at a diabetes education centre. A team of diabetes educator nurses performed a clinical examination for evidence of lipohypertrophy and a separate team of ultrasonographers examined participants in a blinded fashion.

RESULTS

The echo signature for lipohypertrophy consisted of location in the subcutaneous layer and lesions that were 1) well circumscribed either by hyperechoic foci with defined borders or a nodular shape with a hypoechoic halo, 2) heterogeneous in echotexture compared with surrounding tissue, 3) associated with distortion of surrounding connective tissue with 4) absence of vascularity and 5) absence of capsule. Ultrasonography identified individuals with lipohypertrophy significantly more frequently than inspection or palpation (P<0.0001). Inter-observer agreement was moderate (κ=0.50) and limited by the presence of subclinical lesions in 73% of the participants.

CONCLUSIONS

The ultrasound detection of lipohypertrophy is consistent with clinical examination and is reproducible using a defined echo signature. (ClinicalTrials.gov registration no: NCT02348099).

Pretransplant HLA antibodies are associated with reduced graft survival after clinical islet transplantation

Despite significant improvements in islet transplantation, long-term graft function is still not optimal. It is likely that both immune and nonimmune factors are involved in the deterioration of islet function over time. Historically, the pretransplant T-cell crossmatch and antibody screening were done by anti-human globulin--complement-dependent cytotoxicity (AHG-CDC). Class II antibodies were not evaluated. In 2003, we introduced solid-phase antibody screening using flow-based beads and flow crossmatching. We were interested to know whether pretransplant human leukocyte antigen (HLA) antibodies or a positive flow crossmatch impacted islet function post-transplant. A total of 152 islet transplants was performed in 81 patients. Islet function was determined by a positive C-peptide. Results were analyzed by procedure. Class I and class II panel reactive antibody (PRA) > 15% and donor-specific antibodies (DSA) were associated with a reduced C-peptide survival (p<0.0001 and p<0.0001, respectively). A positive T- and or B-cell crossmatch alone was not. Pretransplant HLA antibodies detectable by flow beads are associated with reduced graft survival. This suggests that the sirolimus and low-dose tacrolimus-based immunosuppression may not control the alloimmune response in this presensitized population and individuals with a PRA > 15% may require more aggressive inductive and maintenance immunosuppression, or represent a group that may not benefit from islet transplantation.

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.

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.

Inhibitory effects of immunosuppressive drugs on insulin secretion from HIT-T15 cells and Wistar rat islets

Until recently, islet allotransplantation for type 1 diabetic patients has been largely unsuccessful. Previous pharmacologic studies of single drugs have suggested that one factor contributing to this poor success is toxicity of immunosuppressive drugs on transplanted islets. However, no comprehensive study of agents currently used for islet transplantation has been previously reported. Consequently, we exposed HIT-T15 cells and Wistar rat islets to various concentrations of five immunosuppressive agents for 48 and 24 hr, respectively, and measured glucose-stimulated insulin secretion during subsequent static incubations. Results are expressed as percent reduction of insulin secretion at the lower and upper limits, respectively, of plasma drug concentrations used in clinical transplantation compared with control (no drug exposure). Insulin secretion from HIT-T15 cells was significantly inhibited by 74% and 90% after exposure to methylprednisolone (P<0.05), 11% and 24% after exposure to cyclosporine (P<0.01), 60% and 83% after exposure to mycophenolate (P<0.05), 56% and 63% after exposure to sirolimus (P<0.001), and 10% and 20% after exposure to tacrolimus (P<0.001). Insulin secretion from Wistar rat islets was reduced by 0% and 48% after exposure to mycophenolate (P<0.001) and 20% and 31% after exposure to tacrolimus (P<0.05). No reduction in insulin secretion was observed from either HIT-T15 cells or rat islets after exposure to daclizumab. The results support the hypothesis that toxicity of certain immunosuppressive drugs on beta-cell function plays a role in the poor success of islet allotransplantation. This is especially true of intrahepatically transplanted islets, which are exposed to higher portal concentrations of immunosuppressive agents. These findings support the use of low-dose immunosuppressive drug protocols in clinical islet transplantation.

Restored hypoglycemic counterregulation is stable in successful pancreas transplant recipients for up to 19 years after transplantation

BACKGROUND

Pancreas transplantation has been shown to fully restore glucagon response and partially restore epinephrine response to hypoglycemia during the first few years after transplantation in patients with type 1 diabetes. However, prior studies have not examined hypoglycemic counterregulation in any pancreas transplant recipient of more than 6 years' duration.

METHODS

To determine whether restoration of hypoglycemic counterregulation is maintained over a prolonged period after transplantation, we studied counterregulatory responses and symptom recognition in two groups of pancreas transplant recipients using a stepped hypoglycemic, hyperinsulinemic clamp. Group 1 consisted of 11 successful transplant recipients of 11 to 19 years' duration (mean+/-SE, 13.9+/-0.7 years). Group 2A consisted of seven successful pancreas transplant recipients of 5 to 11 years' duration (mean+/-SE, 8.7+/-0.9 years) who had been studied approximately 5 years earlier using the same stepped, hypoglycemic clamp technique.

RESULTS

Both groups had significant rises in plasma glucagon during the hypoglycemic clamp similar to that seen in short-term recipients and normal controls. Both groups also had significant increases in plasma epinephrine responses similar to that seen in short-term transplant recipients but less than that of normal control subjects. The mean symptom scores of group 1 were significantly less than those of the control group at glucose levels of 60 and 50 mg/dL but not at 40 mg/dL. The mean symptom scores of group 2A were not significantly different than that of control subjects.

CONCLUSION

These results indicate that the restoration of hypoglycemic counterregulation by pancreas transplantation remains stable in successful pancreas transplant recipients for up to 19 years after transplantation.

Managing myocardial infarction in the diabetic patient

Myocardial infarction is the leading cause of death among persons with diabetes. Recent advances in the understanding and treatment of cardiovascular disease in diabetes have made it increasingly important to tailor therapy when treating this high-risk population. Because patients with diabetes are at significantly higher risk for complications and death from MI, these patients are most likely to benefit from early and aggressive therapeutic intervention. Strong recommendations can be given for the use of beta-blockers, ACE inhibitors, and thrombolysis when indicated in the management of acute MI in the diabetic patient. Acetylsalicylic acid is also likely to be beneficial with little risk of adverse events in this setting. In the absence of more definitive data, cautious use of mechanical intervention in diabetic patients is recommended. The use of intravenous insulin therapy may benefit diabetic patients during the acute phase of MI, but more definitive studies are required before it can be recommended for broad use.