Clinical determinants of glucose homeostasis after pancreas transplantation

Glucose metabolism after pancreas-kidney transplantation

Simultaneous pancreas-kidney (SPK) transplantation is a promising treatment option for patients with type 1 diabetes and end-stage renal disease. Most of these patients can achieve normalization of glucose and hemoglobin A(1c) levels. Patient and graft survival continues to improve; however, defects in beta-cell function and insulin resistance can be seen over time after transplant. Various methods can be used to assess the SPK recipient for the development of hyperglycemia and graft dysfunction, with treatment aimed at minimizing diabetogenic immunosuppression, using agents that may preserve beta-cell function, and improving insulin resistance.

The long-term management of pancreas transplantation

Diabetes mellitus (DM) is a major health problem worldwide, which affects 18.2 million individuals (6.3% of the population) in the United States. Currently, the prevalence of Type 1 DM in the United States is estimated to be 1,000,000 individuals, and 30,000 new cases are diagnosed each year. In addition to end-stage renal disease (ESRD), DM is associated with blindness, accelerated atherosclerosis, dyslipidemia, cardio- and cerebrovascular disease, amputation, poor quality of life, and overall lifespan reduction. It accounts for more than 160,000 deaths per year in the United States alone. In 2002, the annual national direct and indirect costs of Types 1 and 2 DM exceeded $130 billion, which included hospital and physician care, laboratory tests, pharmaceutical products, and patient workdays lost because of disability or premature death. Hyperglycemia alone or in concert with hypertension is the primary factor influencing the development of major diabetic complications. From 1990 to 2001, the number of existing ESRD cases to DM increased by more than 300%, while the rate per million populations increased from 167% to 491%. The number is expected to grow 10-fold by 2030 to 1.3 million accounting for 60% of ESRD population. To date, DM is the leading indication for transplantation and is the cause of ESRD in more than 40% of all transplant recipients each year.

In vivo imaging of human pancreatic microcirculation and pancreatic tissue injury in clinical pancreas transplantation

Pancreatitis remains to be a major complication following clinical pancreas transplantation. We performed orthogonal polarized spectral (OPS) imaging for direct in vivo visualization and quantification of human pancreatic microcirculation in six healthy donors for living donor liver transplantation and 13 patients undergoing simultaneous pancreas-kidney transplantation. We further determined the impact of microvascular dysfunction during early reperfusion on pancreatic graft injury. Exocrine and endocrine pancreatic impairment was determined by analysis of serum lipase, amylase and C-peptide levels. Compared to normal pancreas in liver donors (homogeneous acinar perfusion) functional capillary density (FCD) and capillary red blood flow velocity of reperfused grafts were significantly decreased. Elevated CRP concentrations on day 2 post-transplant and serum lipase and amylase levels determined on days 4-5 significantly correlated with microvascular dysfunction during the first 30 min of graft reperfusion. Post-transplant serum C-peptide also correlated significantly with pancreatic capillary perfusion. OPS imaging allows to intra-operatively assess physiologic pancreatic microcirculation and to determine microcirculatory impairment during early graft reperfusion. This impairment correlated with the manifestation of post-transplant dysfunction of both exocrine and endocrine pancreatic tissue. OPS imaging may be used clinically to determine the efficacy of interventions, aiming at attenuating microcirculatory impairment during the acute post-transplant reperfusion phase.

EFFECT OF VENOUS DRAINAGE SITE ON INSULIN ACTION AFTER SIMULTANEOUS PANCREAS-KIDNEY TRANSPLANTATION

BACKGROUND

The aim of the present study was to determine the influence of the venous drainage site on insulin homeostasis in simultaneous pancreas-kidney (SPK) transplant recipients.

METHODS

The study included 12 SPK patients with portal venous drainage (P) and 11 SPK patients with systemic venous drainage (S) of pancreas allograft. All of the participants presented similar characteristics. The euglycemic hyperinsulinemic clamp was performed using a 0.4-mU/kg/min insulin infusion. An infusion of [6,6-(2)H2] glucose was used to determine glucose turnover at the basal state and during the clamp to determine liver and peripheral tissue sensitivity to insulin.

RESULTS

Minor changes in glycemia and insulinemia were shown: fasting plasma glucose was significantly higher in the SPK-P group and insulinemia was higher in the SPK-S group. Hepatic glucose production was similar in both groups. During the clamp, insulin levels were higher in SPK-S recipients, but hepatic glucose production was suppressed in both groups. Glucose use was lower in SPK-S recipients than in SPK-P recipients, 3.32 +/-1.41 mg/kg/min and 4.70 +/-1.64 mg/kg/min, respectively (P<0.02). Basal and under-clamp free fatty acid levels were similar. In addition, no significant difference in cholesterol and low-density lipoprotein levels was shown, whereas high-density lipoprotein levels were higher in the SPK-S group; triglycerides during fasting and under clamp were significantly higher in the SPK-P group.

CONCLUSIONS

In both groups, neither hepatic nor peripheral insulin resistance was detected. In SPK-S recipients, the authors have showed only a lower insulin clearance and a slight decreased peripheral responsiveness to insulin without modifications of lipid status.

Successful PTA and stenting for acute iliac arterial injury following pancreas transplantation

Iliac artery injuries may occur during solid organ transplantation. We describe an approach to an iliac artery clamp injury after pancreatic allotransplantation. The patient is a 48-year-old diabetic male who underwent successful cadaveric pancreatico-duodenal transplantation complicated by a left common iliac artery clamp injury. The injury resulted in both graft and lower leg ischemia. The injury was recognized promptly and diagnosed by magnetic resonance angiogram (MRA). The lesion was successfully treated with percutaneous transluminal angioplasty and stenting with resolution of both graft and leg ischemia. We propose this technique as a minimally invasive approach to an iliac injury that can be used to treat vascular injuries during solid organ transplantation.

[Pancreas and kidney transplantation: long-term metabolic results]

STUDY AIM

Pancreas and kidney transplantation (PKTx) is indicated in uremic patients with insulin-dependent diabetes mellitus (IDDM). The aim of this study was to determine its long-term effect on metabolic control in order to establish the real efficacy of this treatment in diabetic patients.

PATIENTS AND METHOD

Among a total experience of 191 pancreas and kidney transplantations, a metabolic control was performed in 80 patients who underwent PKTx in our center, with both grafts functioning for more than one year. Immunological markers of diabetes mellitus were also evaluated (ICA and GADab) in 50 patients.

RESULTS

Basal glycemia and glycosylated hemoglobin (HbA1c) levels throughout follow-up were within the normal range. Hyperinsulinemia was present throughout follow-up till the fourth year. The oral glucose tolerance test (OGTT) was normal in 82.5% of the patients beyond one year after the graft. Over time, no differences were detected on basal glucose and insulin levels and areas under the curve (AUC) of glycemia and insulinemia. During the evolution, no differences were found in the fasting insulin resistance index (FIRI), in spite of increasing body weight. ICA were + in 2 patients before graft and + in 7 after graft (14%). GADab were + in 10 patients before graft and + in 11 after graft (22%).

CONCLUSION

Pancreas and kidney transplantation provides without any insulin treatment and diet long-term normalization of glycemic control, assessed by HbA1c and OGTT, despite the existence of sustained hyperinsulinemia. Our results strongly suggest that pancreas and kidney transplantation is the most efficient treatment for uremic patients with insulin-dependent diabetes mellitus from a metabolic point of view.

Trends and perspectives in pancreas and simultaneous pancreas and kidney transplantation

Pancreas transplantation is still the best option to achieve normoglycaemia and insulin independence in patients with type I diabetes. As a result of improvements in surgical techniques, immunosuppression and patient selection, one year survival rates of 95, 83, and 88% for patient, pancreas, and kidney survival, respectively, are reported for patients with simultaneous pancreas and kidney transplantation. The main goals for the future are to reduce postoperative morbidity, to identify the relevant indications for single pancreas transplantation, to adopt the best surgical technique for individual patients' needs (bladder versus enteric drainage with or without portal venous delivery of insulin), and to develop immunosuppressive strategies with low nephrotoxic and diabetogenic potential.

Ulceration of the urethral meatus after simultaneous pancreas-kidney transplantation

A 39-year-old male developed painful ulceration of the glans penis following simultaneous pancreas and kidney transplantation for end-stage renal failure complicating insulin-dependent diabetes mellitus. Infection was excluded. Diversion of the pancreatic secretions away from the urinary bladder into the bowel resulted in healing.

Insulin secretion and sensitivity after simultaneous pancreas-kidney transplantation estimated by continuous infusion of glucose with model assessment

BACKGROUND

Monitoring of insulin secretion and sensitivity after pancreas transplantation remains a practical problem.

METHODS

We introduced the simple structural model, continuous infusion of glucose with model assessment (CIGMA), to obtain insulin secretion and insulin sensitivity estimations after 35 successful simultaneous pancreas-kidney transplantations. Eighteen non-diabetic kidney transplant recipients were used as control group.

RESULTS

The baseline characteristics were equal between the two groups except for higher fasting insulin levels in the pancreas transplant group. After the 1-hr CIGMA glucose load, the pancreas transplant group reached a mean +/- SD blood glucose of 8.2+/-1.7 mmol/L compared with 7.3+/-1.0 mmol/L in the control group (P = 0.05). Concurrent stimulated insulin and C-peptide levels were 48+/-28 mU/L and 2.3+/-0.9 nmol/L in the pancreas transplant group compared with 36+/-21 mU/L and 2.9+/-1.1 nmol/L in the control group (P = 0.1 and P = 0.03, respectively). Both the CIGMA estimation for secretion as well as the CIGMA estimation for sensitivity were lower in pancreas transplant group (P = 0.003 and P = 0.01, respectively). Mean +/- SE coefficients of variation for the model estimations were 15+/-4% for secretion and 17+/-6% for sensitivity.

CONCLUSIONS

We conclude that CIGMA can be used clinically to evaluate carbohydrate metabolism in pancreas-kidney transplant recipients. These patients have a reduction in insulin secretory capacity and evidence of more insulin resistance than non-diabetic kidney transplant recipients.

Progression of macrovascular disease after transplantation

INTRODUCTION

Cardiovascular and cerebrovascular disease are major causes of morbidity and mortality after kidney transplantation. The aim of this longitudinal study was to examine the natural history of carotid plaque and to determine risk factors for the progression of vascular disease in uremic, type 1 diabetic patients who received a combined kidney and pancreas transplant.

METHODS

Carotid artery (n=765) and lower limb vascular duplex scanning (n=656) were prospectively undertaken in 82 recipients before transplantation, at 6 months, and then at annual intervals for up to 10 years. Plaque in the internal carotid artery (ICA), external carotid artery, and common carotid artery was classified by type, location, extent, and degree of functional obstruction, and evaluated using multivariate analysis.

RESULTS

Carotid plaque was present in 22.5% of patients at initial scanning, but increased to 56.6% by 7-10 years after transplantation, especially in the ICA and common carotid artery. Both the severity and extent of plaque increased, and plaque became more complex and heterogeneous with time after transplantation (P<0.001). Carotid plaque was associated with older age, current cigarette smoking, hyperphosphatemia, hypoalbuminemia, duration of pretransplantation dialysis, and presence of lower limb plaque (P<0.05-0.001). The severity of carotid plaque increased in older, hypertensive recipients and was associated with metabolic acidosis and hyperphosphatemia (all P<0.05). Severity of ICA disease correlated with disease in the contralateral ICA (r=0.57, P<0.001) and femoral arteries (r=0.42, P<0.001). Paradoxically, each carotid artery progressed independently of the other. ICA disease severity progressed when heterogenous, calcified, or new plaque was present on scanning, and with reduced renal transplant function (P<0.01-0.001). The mean ICA blood flow remained stable with time but was progressively impaired by hypertension, fasting hyperglycemia, and a lower prednisolone dose (P<0.05). Cerebrovascular events occurred in only four patients and were unrelated to carotid disease, implying relative plaque stability.

CONCLUSION

Extensive carotid vascular wall abnormalities increased significantly despite kidney and pancreas transplantation. Initiation of plaque was associated with systemic factors, whereas progression of established plaque was largely influenced by local factors within the arterial wall.

Pancreas and pancreas-kidney transplantation

Pancreas transplantation consistently results in an insulin-independent normoglycemic state in insulin-dependent diabetic recipients. Registry data show insulin independence is achieved in 80% of simultaneous kidney and pancreas recipients, more than 70% of pancreas after kidney recipients, and more than 60% of nonuremic pancreas transplant alone recipients. Advances in immunosuppression and careful monitoring for rejection in conjunction with biopsies are largely responsible for improved results. However, complications do occur, and improvements in surgical technique and patient care continue to evolve.

Diabetic neuropathy after pancreas transplantation: determinants of recovery

Although simultaneous pancreas and kidney transplantation (SPK) achieves normoglycemia and correction of uremia in type I diabetic patients with renal failure, little data are available on long-term outcome and clinical determinants of recovery of peripheral neuropathy. In this prospective study, 219 electrophysiological studies using a standardized protocol were performed before and up to 8 years after SPK in 44 patients. Nine control diabetic recipients with functioning kidney but nonfunctioning pancreas transplants were studied on 35 occasions. Patients were 38.5+/-7.9 years old (mean+/-SD) with pretransplant diabetes present for 25.2+/-7.6 years. Significant polyneuropathy (total nerve conduction scores [NCS] <-1.0) was present in 89% before transplantation, which correlated with body weight (r=0.628, P<0.001). Two distinct patterns of neurological recovery were observed after SPK. Conduction velocity (CV) improved in a biphasic pattern, with a rapid initial recovery followed by subsequent stabilization. In contrast, the recovery of nerve amplitude was monophasic, and continued to improve for up to 8 years. Initial improvement in NCS was primarily due to an increase in CV (P=0.002 vs. baseline), and was best in shorter and younger patients. Recovery of total NCS at 6 months after SPK, assessed by multivariate analysis, was least in obese recipients and when performed in patients who had started dialysis before SPK, and was associated with lower transplant kidney isotopic glomerular filtration rate and HLA mismatch (P<0.05 to 0.001). Subsequent improvement was associated with less severe initial neuropathy, smaller body weight, and longer duration of diabetes (P<0.01 to 0.001). Fasting hyperinsulinemia was associated with impairment of initial recovery and subsequent NCS after SPK, but was worse in the control group. Recovery of nerve action potential amplitudes was predicted by better initial amplitudes and HLA mismatch, lower body weight, and the use of nifedipine (P<0.05 to 0.001). Nifedipine was used for hypertension in 33% of SPK and was associated with better CV and amplitudes, particularly in the upper limbs, where there was less neuropathy. The use of angiotensin-converting enzyme inhibitors also appeared beneficial, but this was confined to the lower limbs. SPK resulted in a gradual, sustained, and late improvement in nerve action potential amplitudes, consistent with axonal regeneration and partial reversal of diabetic neuropathy. These data suggest that early transplantation of uremic diabetic patients before onset of severe neuropathy, minimizing obesity and optimizing renal transplant function, maximizes neurological recovery after SPK. Furthermore, the preliminary data support randomized clinical trials for evaluation of nifedipine and angiotensin-converting enzyme inhibitors in diabetic neuropathy.

Simultaneous pancreas and kidney transplant rejection: separate or synchronous events?

The results of simultaneous pancreas and kidney transplantation (SPK) cannot be matched by pancreas transplantation alone (PTA), in part because an independent diagnosis of pancreas graft rejection remains difficult. The relationship between rejection of the pancreas and rejection of the kidney is poorly understood, and it is not known whether simultaneous transplantation of both organs confers true protection to either graft. To study these questions, reliable canine allotransplant models of kidney transplantation alone (KTA), PTA, and SPK were established. Sixty-seven mongrel dogs received KTA (n=21), PTA (n=23), or SPK (n=23) with either no immunosuppression, low-dose cyclosporine (CsA)-based immunosuppression, or high-dose CsA-based immunosuppression. Needle core biopsy (NCB) and fine needle aspiration biopsy (FNAB) were performed at 0, 2, 4, 7, 9, 11, 14, 21, and 30 days or at the time of graft failure. Pancreas and kidney graft survival after SPK was significantly shorter in dogs given low-dose CsA than in dogs given high-dose CsA (pancreas, P<0.04; kidney, P<0.03). Concurrent NCBs and FNABs were performed on 227 occasions in pancreas grafts and 229 occasions in kidney grafts. The time to initial evidence of rejection by NCB was not different in any immunosuppressed group. Synchronous rejection occurred in 73% of immunosuppressed SPK biopsies. Kidney-only rejection occurred in 23% of biopsies and pancreas-only rejection occurred in only 3% after SPK. All markers of pancreas graft rejection were poor, with the most sensitive being NCB of the simultaneously transplanted kidney. In summary, recipients of SPK required more immunosuppression than recipients of PTA, and improved PTA survival should be achievable with more sensitive markers of rejection. Markers of kidney rejection were the most sensitive indicators of pancreas rejection, and independent pancreas rejection was uncommon after SPK.