Glucose metabolism in the first 3 years after renal transplantation in patients receiving tacrolimus versus cyclosporine-based immunosuppression.

The long-term effects of tacrolimus and cyclosporine on pancreatic islet cell function in renal transplant recipients are unclear. Therefore, a prospective, randomized, longitudinal study was performed that compared glucose metabolism in adult kidney allograft recipients on tacrolimus versus cyclosporine-based immunosuppression. Twenty-three white renal allograft recipients, randomized for either therapy with cyclosporine or tacrolimus, underwent intravenous glucose tolerance tests 6 times during the first 3 yr after transplantation. Concomitant therapy (low-dose steroids and azathioprine) was the same in both groups. Insulin sensitivity index (kG), insulin resistance (insulin/glucose ratio and homeostasis model assessment), and C-peptide and insulin secretion were calculated. Trough levels of tacrolimus and cyclosporine were measured. The occurrence of posttransplantation diabetes mellitus was prospectively monitored. Statistical analysis was performed by ANOVA for repeated measures, and parametric and nonparametric tests were also performed. Although only one patient treated with cyclosporine developed posttransplantation diabetes mellitus, kG levels were below normal in up to one-third of both patients who received tacrolimus and cyclosporine. The only significant difference between patients who received tacrolimus and those who received cyclosporine was in pancreatic secretion capacity at week 3 after transplantation, when the increment of C-peptide secretion was 57% lower and the increment of insulin secretion was 48% lower for patients receiving tacrolimus. In both groups, from week 3 to month 6, there was a tendency toward an increase in kG, despite a significant increase in fasting glucose and insulin resistance calculated by homeostasis model assessment. After month 6, there were no significant changes in any of the parameters of glucose metabolism, indicating that long-term use of either tacrolimus or cyclosporine does not cause chronic, cumulative pancreatic toxicity.     

Glucose metabolism after pancreas transplantation: cyclosporine versus tacrolimus

BACKGROUND: The results of the new immunosuppressants in simultaneous pancreas-kidney transplantation (SPK) concerning organ survival and rejection rates are excellent. Tacrolimus as well as cyclosporine are assumed to be diabetogenic; however, there are no comparative studies investigating their effects on glucose metabolism. METHODS: One hundred thirty-six type 1 diabetic patients who had undergone successful SPK were investigated. Glucose and insulin levels during an oral glucose tolerance test as well as hemoglobin (Hb) A1c were analyzed. Investigations were performed early (3 months, n = 136) and late (3 years, n = 83) after transplantation. Graft recipients were grouped according to the first-line immunosuppression: group 1, cyclosporine; group 2, tacrolimus. There were no differences concerning age, gender, body mass index, and renal function between the groups. RESULTS: Early after transplantation, there was no difference between the groups concerning fasting glucose, HbA1c levels, basal and stimulated insulin secretion, and incidence of normal glucose tolerance. Late after transplantation, the incidence of a normal glucose tolerance tended to be lower (70% vs. 78%), whereas HbA1c (5.3% vs. 5.0%) and fasting glucose (81 vs. 78 mg/dL) levels tended to be higher in tacrolimus-treated patients. However, these differences were not significant. Insulin secretion was not reduced in the tacrolimus group. CONCLUSIONS: Concerning glucose metabolism and secretory capacity of the pancreas graft, no significant differences were found comparing tacrolimus- versus cyclosporine-treated graft recipients.     

Prospective, multicenter, randomized trial to compare incidence of new-onset diabetes mellitus and glucose metabolism in patients receiving cyclosporine microemulsion versus tacrolimus after de novo kidney transplantation

New-onset diabetes mellitus (NODM) is associated with increased risk of graft failure and death in renal transplant recipients. Some clinical studies have indicated that NODM risk is higher with tacrolimus than cyclosporine, but no comparative trial has used American Diabetic Association (ADA)/World Health Organization (WHO) criteria for diagnosis of diabetes mellitus. The Diabetes Incidence After Renal Transplantation, Neoral C2 Monitoring Versus Tacrolimus (DIRECT) study is a 6-month open-label, multicenter trial comparing the impact of tacrolimus and Neoral (cyclosporine microemulsion) on glucose metabolism in 700 de novo kidney transplant recipients, based on ADA/WHO criteria. Patients are randomized to tacrolimus (C0 monitoring) or Neoral (C2 monitoring), stratified by baseline diabetic status and ethnicity. All patients receive basiliximab, corticosteroids, and mycophenolate mofetil or enteric-coated mycophenolate acid (myfortic). Pooled interim 3-month results from a subset of 115 patients receiving either tacrolimus or Neoral showed that the primary efficacy end-point (biopsy-proven acute rejection [BPAR], graft loss or death) occurred in 11 patients (10%). There were four graft losses and only one death, which occurred after graft loss. Eight patients experienced BPAR (7.3%). Among 99 patients who were nondiabetic at baseline, 14 developed NODM by month 3, 17 developed impaired fasting glucose or impaired glucose tolerance, and another 5 patients received hypoglycemic treatment for at least 14 consecutive days or at the month 3 visit, resulting in a 36% incidence of impaired glucose metabolism. At 3 months, median GFR (Nankivell) was 63.7 mL/min; median serum creatinine was 137 micromol/L. Full complete results are expected in December 2005.     

The Higher Diabetogenic Risk of Tacrolimus Depends on Pre‐Existing Insulin Resistance. A Study in Obese and Lean Zucker Rats

Insulin resistance may interact with calcineurin inhibitors, enhancing the diabetogenic effect of tacrolimus compared with cyclosporine‐A. We studied both drugs in insulin‐resistant animals: obese Zucker rats (n = 45), and insulin‐sensitive animals: lean Zucker rats (n = 21). During 11 days, animals received saline‐buffer, cyclosporine‐A (2.5 mg/kg/day) or tacrolimus (0.3 mg/kg/day). At Days 0 and 12 animals underwent intraperitoneal glucose tolerance test (0–30–60–120 min). Islet morphometry, beta‐cell proliferation, apoptosis and Ins2 gene expression were analyzed. By Day 12, no lean animal had developed diabetes, while all obese animals on tacrolimus and 40% on cyclosporine‐A had. In obese animals, tacrolimus reduced beta‐cell proliferation and Ins2 gene expression compared with cyclosporine‐A. Five days after treatment discontinuation, partial recovery was observed, with only 10% and 60% of the animals on cyclosporine and tacrolimus remaining diabetic respectively. Beta‐cell proliferation increased in animals on tacrolimus while Ins2 gene expression remained unaltered. In conclusion, insulin resistance exacerbated the diabetogenic effect of tacrolimus compared with cyclosporine‐A. This may be explained by greater inhibition of Ins2 gene and beta‐cell proliferation by tacrolimus in the insulin resistant state. Discontinuation of the drugs may allow the recovery of the metabolic alterations.     

No influence of immunosuppression on insulin sensitivity and beta-cell function in living donor liver transplantation

In liver transplantation alterations of glucose metabolism are common but not well understood. Influence of immunosuppression is widely presumed but has not proven until now. Using a frequently sampled intravenous glucose tolerance test with a minimal modeling technique of glucose disappearance we analyzed insulin sensitivity (SI) and beta-cell function (first and second phase of pancreatic beta-cell secretion, Phi 1 and Phi 2) in living donor liver transplantation of the right lobe. Initial immunosuppression in recipients was done with tacrolimus, prednisolone, and basiliximab induction. Donors and recipients were investigated before and 10 days, 6 months, and 1 year after operation. Normal SI of controls (donors before operation) decreased markedly 10 days after right lobectomy to SI 2.22 +/- 0.35 x 10(-4) min(-1) x microU/mL (P < .001); Phi 2 was compensatory increased. All parameters normalized within 1 year. Recipients were insulin-resistant with hyperinsulinemia before transplantation. After transplantation no parameter was significantly different from donors; all normalized equally to donors over 1-year follow-up. Thus, immunosuppression in recipients has no influence on glucose metabolism because liver function itself seems to play a more pronounced role than known until now.     

Relative risk of new-onset diabetes during the first year after renal transplantation in patients receiving tacrolimus or cyclosporine immunosuppression

Clinical trials have consistently shown a higher incidence of new-onset diabetes mellitus with tacrolimus than cyclosporine. However, in protocol-driven studies steroid doses are comparable in both treatment arms, while in clinical practice steroid dose used in conjunction with tacrolimus or cyclosporine may differ. This retrospective study analysed renal transplant recipients without pre-existing diabetes receiving tacrolimus (n = 100) or cyclosporine (n = 100) for whom one-year follow-up data were available. Diabetes was defined as use of insulin or oral hypoglycemic agents; fasting glucose >6.9 mmol/L; or non-fasting glucose >11 mmol/L on three consecutive occasions. Tacrolimus-treated patients were significantly older than cyclosporine-treated patients (49 +/- 14 vs. 44 +/- 13 yr, p < 0.05) and received a significantly lower cumulative dose of corticosteroids over the first three months post-transplant (1284 +/- 379 vs. 1714 +/- 486 mg, p < 0.0001). At 3, 6, 9 and 12 months significantly more tacrolimus-treated patients had new-onset diabetes than cyclosporine- treated patients. At 12 months, 18 patients receiving tacrolimus and two receiving cyclosporine had diabetes (p < 0.0001). There was a clear relationship between age and incidence of new-onset diabetes at three months in the tacrolimus cohort. After stratifying patients by age group, the frequency of diabetes was significantly higher with tacrolimus than with cyclosporine in patients aged 40-60 yr [8/46 (17.4%) vs. 2/48 (4.2%), p < 0.05] and >60 yr [9/28 (32.1%) vs. 0/14 (0%), p < 0.05]. The mean tacrolimus trough level during the first three months was similar in patients with diabetes (13.1 +/- 2.3 ng/mL) or without diabetes (13.0 +/- 2.8 ng/mL, n.s.). These results indicate that new-onset diabetes is strongly and significantly associated with tacrolimus vs. cyclosporine in renal transplant recipients, even when steroid dosing is lower with tacrolimus.     

Conversion from tacrolimus to cyclosporin is associated with a significant improvement of glucose metabolism in patients with new-onset diabetes mellitus after renal transplantation

BACKGROUND: The incidence of new-onset posttransplant diabetes mellitus (PTDM) is increased in renal transplant patients treated with tacrolimus. METHODS: We retrospectively analyzed fasting plasma glucose and HbA1c levels as well as the dose of glucose-lowering agents in 34 renal transplant patients converted from tacrolimus to cyclosporine (CsA) for PTDM. Diabetes was defined according to current guidelines as repeated fasting plasma glucose (FPG) levels > or =126 mg/dL. RESULTS: At conversion, 11 patients received insulin, 5 received oral agents, and 18 had no glucose-lowering therapy. Fasting plasma glucose levels decreased from 146 +/- 64 mg/dL at conversion to 111 +/- 26 mg/dL at 3 months and 104 +/- 21 mg/dL at 12 months (P < .001). HbA1c levels decreased from 6.8 +/- 0.8% at conversion to 6.0 +/- 0.6% at 12 months (P = .001). Insulin was stopped in 3, the dose reduced in 7, and remained stable in 1 of the patients. The average daily insulin dose among these patients was reduced from 31 +/- 17 units at conversion to 13 +/- 12 units at 12 months (P < .05). There was no significant change in the number of patients treated with oral glucose-lowering agents. Diabetes reversed (fasting plasma glucose < or = 125 mg/dL without glucose-lowering therapy) in 44% (95% confidence interval, 23% to 64%) of patients during the first year after conversion (P < .001). Graft function, blood pressure, and lipid levels remained stable after conversion but the proportion of patients receiving lipid-lowering therapy increased from 18% to 49% (P < .01). CONCLUSIONS: Conversion from tacrolimus to CsA for PTDM was associated with a marked improvement in glucose metabolism and frequent reversal of diabetes.     

Influence of tacrolimus on glucose metabolism before and after renal transplantation: a prospective study

Most studies concerning the influence of tacrolimus on glucose metabolism have been performed either in animals or after organ transplantation. These clinical studies have largely been transversal with patients who were using steroids. Therefore, this prospective, longitudinal study investigated the influence of tacrolimus on glucose metabolism before and after transplantation. Eighteen Caucasian dialysis patients underwent an intravenous glucose tolerance test before and 5 d after the start of tacrolimus. Insulin sensitivity index (k(G)), insulin resistance (insulin/glucose ratio and homeostasis model assessment), and C-peptide and insulin secretion were calculated. Trough levels of tacrolimus were measured. After transplantation, the occurrence of posttransplantation diabetes mellitus (PTDM) was prospectively monitored. Statistical analysis was performed using the Wilcoxon signed ranks test and Spearman's rho for correlation. Before tacrolimus, k(G) was indeterminate in three patients. During tacrolimus, k(G) decreased in 16 of 18 patients, from a median of 1.74 mmol/L per min to 1.08 mmol/L per min (P<0.0001). The correlation between C-peptide and insulin data was excellent. Insulin secretion decreased from 851.0 mU x min/L to 558.0 mU x min/L (P = 0.014), whereas insulin resistance did not change. Insulin sensitivity correlated negatively with tacrolimus trough level. After transplantation, three patients developed PTDM; before tacrolimus, two had an indeterminate and one a low normal k(G). During tacrolimus administration, k(G) decreased in almost all patients as a result of a diminished insulin secretion response to a glucose load, whereas insulin resistance did not change. Patients with an abnormal or indeterminate k(G) seem to be at risk of developing PTDM while on tacrolimus.     

Early differential defects of insulin secretion and action in 19-year-old caucasian men who had low birth weight

Several studies have linked low birth weight (LBW) and type 2 diabetes. We investigated hepatic and peripheral insulin action including intracellular glucose metabolism in 40 19-year-old men (20 LBW, 20 matched control subjects), using the hyperinsulinemic-euglycemic clamp technique at two physiological insulin levels (10 and 40 mU/m(2) per min), indirect calorimetry, and [3-(3)H]glucose. Insulin secretion was examined during an oral and intravenous glucose tolerance test. Fasting p-glucose was higher in the LBW group (5.6 +/- 0.1 vs. 5.4 +/- 0.1; P < 0.05). Basal plasma glycerol concentrations were significantly lower in the LBW group. Insulin-stimulated glycolytic flux was significantly reduced, and suppression of endogenous glucose production was enhanced in the LBW group. Nevertheless, basal and insulin-stimulated rates of whole-body peripheral glucose disposal, glucose oxidation, lipid oxidation, exogenous glucose storage, and nonoxidative glucose metabolism were similar in the two groups. Insulin secretion was reduced by 30% in the LBW group, when expressed relative to insulin sensitivity (disposition index = insulin secretion x insulin action). We propose that reduced insulin-stimulated glycolysis precedes overt insulin resistance in LBW men. A lower insulin secretion may contribute to impaired glucose tolerance and ultimately lead to diabetes.     

Glucose metabolism before and after conversion from cyclosporine microemulsion to tacrolimus in stable renal recipients.

BACKGROUND: Tacrolimus is more diabetogenic than cyclosporine. However, this difference is only discernible in the first few months after renal transplantation. In randomized trials, investigating the effects of immunosuppression after renal transplantation, no increase in diabetes mellitus has been reported. However, no sensitive technique was used in these trials, so subclinical alteration of glucose metabolism cannot be excluded. METHODS: We, therefore, decided to use an intravenous glucose tolerance test (IV-GTT), to investigate whether conversion from cyclosporine-based immunosuppression, with a median trough level of 120 microg/l, to tacrolimus-based immunosuppression with a median trough level of 6.5 microg/l influences glucose metabolism and whether patients on steroids behave differently from those not on steroids. RESULTS: Thirty stable, non-diabetic patients, transplanted 10 or more years earlier, were converted from cyclosporine to tacrolimus without changing their concomitant medication. IV-GTT's were performed before and 2.5 months after the conversion. Before conversion, 40% of the patients had an abnormal glucose disappearance rate (kG): in 7%, kG was below 0.8 (abnormal range) and in 34%, kG was between 0.8 and 1.2 (indeterminate range). After conversion, stimulated insulin production, kG, HbA1C and fasting glucose did not change significantly. Insulin resistance (HOMA-R) of the whole group increased significantly, mainly due to a rise in HOMA-R in patients on steroids (n = 18). None of these patients developed overt diabetes mellitus. CONCLUSIONS: Some 40% of long-term cyclosporine-treated patients had an abnormal glucose metabolism. Conversion from cyclosporine to tacrolimus does not negatively influence stimulated glucose metabolism or insulin resistance in stable, steroid-free renal transplant recipients. However, in patients receiving steroids, conversion leads to an increase in insulin resistance while insulin output remains the same.     

Glucose metabolism in renal transplant recipients: effect of calcineurin inhibitor withdrawal and conversion to sirolimus

Cyclosporine A (CsA) and tacrolimus have been associated with an increased risk for diabetes after transplantation, whereas sirolimus is deemed to be devoid of any effect on glucose metabolism. This study was performed to investigate the effect of the withdrawal of calcineurin inhibitors and the switch to sirolimus on peripheral insulin resistance and pancreatic beta cell response. Twenty-six patients who received a kidney transplant and discontinued CsA and were converted to sirolimus and 15 recipients of suboptimal kidneys who were treated with tacrolimus plus sirolimus for the first 3 mo after grafting and thereafter with sirolimus alone were enrolled. All patients underwent an oral glucose tolerance test and intravenous insulin tolerance test before and 6 mo after the conversion to sirolimus-alone therapy. The withdrawal of CsA or tacrolimus was associated with a significant fall of insulin sensitivity (both P = 0.01) and with a defect in the compensatory beta cell response, as measured by the disposition index (P = 0.004 and P = 0.02, respectively). The increase of insulin resistance and the decrease of disposition index significantly correlated with the change of serum triglyceride concentration after the conversion to sirolimus-based therapy (R(2) = 0.30, P = 0.0002; and R(2) = 0.19, P = 0.004, respectively). Clinically, the switch to sirolimus was associated with a 30% increase of incidence of impaired glucose tolerance and with four patients' developing new-onset diabetes. In conclusion, the discontinuation of calcineurin inhibitors and their replacement by sirolimus fail to ameliorate the glycometabolic profile of kidney transplant recipients. Rather, it is associated with a worsening of insulin resistance and an inappropriately low insulin response.     

Defining optimal immunosuppression for islet transplantation based on reduced diabetogenicity in canine islet autografts

BACKGROUND: The recent results of clinical islet transplantation have improved substantially with the introduction of a more potent but less diabetogenic immunosuppressant protocol. The successful development of this protocol was based in part on the outcomes of studies reported herein, addressing the diabetogenic potential of a series of immunosuppressant agents used alone or in combination in a canine islet autograft model. Although it is recognized that failure to achieve long-term insulin independence in human islet allotransplantation has been multifactorial, with low engraftment mass, acute or chronic rejection, autoimmune recurrence, loss of islet-acinar integrity, heterotopic site, denervation, and insulin resistance all being implicated to varying degrees, avoidance of diabetogenic immunosuppression has been pivotal to the enhanced outcomes of clinical islet transplantation. We here explore the effects of clinically relevant doses of cyclosporine or tacrolimus when given alone or in combination with glucocorticoids on long-term canine islet autograft function. METHOD: Dogs (n=8) underwent total pancreatectomy, islet isolation, and intrasplenic autotransplantation and were normoglycemic with stable long-term graft function 3 months to 8 years posttransplant. The frequently sampled intravenous glucose tolerance test (FSIGT) was performed predrug (baseline), at 1 month of therapy (on drug), and again 1 month after withdrawal of therapy (postdrug). RESULTS: Monotherapy treatments with low- or high-dose prednisone, Neoral, or tacrolimus had minimal impact on islet autograft function. The combination of Neoral and prednisone led to a marked impairment in glucose decay (25% decline from 1.77+/-0.2 to 1.24+/-0.2, P<0.05), without significant change in insulin responsiveness or glucose effectiveness. However, insulin sensitivity was markedly impaired while on therapy (7.10+/-1.2 to 3.10+/-0.5, P<0.01). Importantly, glucose decay and insulin sensitivity failed to return to baseline after withdrawal of therapy. The combination of tacrolimus and glucocorticoids led to permanent and irreversible diabetes in all recipients (n=6, P<0.001). Similar treatment of healthy control dogs led to a 44% decrease in glucose decay (P<0.01). CONCLUSIONS: Immunosuppression must be specifically tailored for islet transplantation and be glucocorticoid free if insulin independence is to be sustained clinically.     

The impact of impaired insulin release and insulin resistance on glucose intolerance after renal transplantation

The current knowledge of the pathogenesis of post-transplant glucose intolerance is sparse. This study was undertaken to assess the relative importance of insulin secretion (ISec) and insulin sensitivity (IS) in the pathogenesis of post-transplant diabetes mellitus (PTDM), impaired glucose tolerance (IGT) and impaired fasting glucose (IFG) after renal transplantation. An oral glucose tolerance test (OGTT) was performed in 167 non-diabetic recipients 10 wk after renal transplantation. Fasting, 1-h and 2-h insulin and glucose levels were used to estimate the insulin secretory response and IS. One year after transplantation 89 patients were re-examined with an OGTT including measurements of fasting and 2 h glucose. Ten weeks after transplantation the PTDM-patients had significantly lower ISec and IS than patients with IGT/IFG, who again had lower ISec and IS than those with normal glucose tolerance (NGT). One year later, a similar difference in baseline ISec was observed between the three groups, whereas baseline IS did not differ significantly. Patients who improved their glucose tolerance during the first year, were mainly characterized by a significantly greater baseline ISec, and they received a significantly higher median prednisolone dose at baseline with a subsequent larger dose reduction during the first year, than the patients who had their glucose tolerance unchanged or worsened. In conclusion, both impaired ISec and IS characterize patients with PTDM and IGT/IFG in the early course after renal transplantation. The presence of defects in insulin release, rather than insulin action, indicates a poor prognosis regarding later normalization of glucose tolerance.     

Insulin resistance and insulin deficiency in the pathogenesis of posttransplantation diabetes in man.

Although steroids can induce insulin resistance, it is not known whether additional defects in insulin secretion are necessary for the development of diabetes. To address this question, we measured insulin sensitivity (euglycemic insulin clamp in combination with indirect calorimetry and infusion of tritiated glucose) and insulin secretion (hyperglycemic clamp) in three groups of subjects: (1) 10 kidney transplant patients with normal oral glucose tolerance, (2) 14 patients who developed diabetes after kidney transplantation, and (3) 10 healthy controls. Glucose utilization, primarily storage of glucose as glycogen, was reduced by 34% in kidney transplant patients with normal glucose tolerance when compared with healthy control subjects (18.2 +/- 2.9 vs. 27.5 +/- 2.7 microM/L; P less than 0.05). Insulin secretion was normal in relation to the degree of insulin resistance in transplanted non-diabetic patients, thus maintaining a normal oral glucose tolerance. Development of transplantation diabetes was associated with only minor further deterioration of glucose storage (14.7 +/- 2.7 microM/L; P less than 0.001 vs. control subjects), whereas first-phase, second-phase, and glucagon-stimulated insulin secretion measured during hyperglycemic clamping (incremental area under the insulin curve 287 +/- 120, 1275 +/- 419, and 3515 +/- 922 pM) became impaired as compared with nondiabetic kidney transplant patients (769 +/- 216, 3084 +/- 545, and 6293 +/- 533 pM; P less than 0.05). We conclude that both insulin resistance and insulin deficiency are necessary for the development of diabetes in kidney transplant patients.     

Rosiglitazone treatment of diabetes mellitus after solid organ transplantation

BACKGROUND: Diabetes mellitus is a common clinical problem after solid organ transplantation. Whether patients have preexisting diabetes or develop posttransplant diabetes, insulin therapy is usually required. Achieving excellent diabetic control is an important target in reducing the incidence of cardiovascular disease after transplantation. METHODS: The authors treated 18 patients with type 2 diabetes after transplantation with rosiglitazone. Eleven patients had preexisting type 2 diabetes and seven patients developed posttransplant diabetes. Rosiglitazone was added to insulin or glyburide to improve elevated hemoglobin Hb A1C levels in patients with preexisting diabetes or was used to try to avoid insulin therapy in posttransplant diabetics. Blood levels of cyclosporine, tacrolimus, creatinine, and HbA1C were followed for a mean of 381 days (range, 133-718 days). RESULTS: The addition of rosiglitazone did not cause any significant changes in serum creatinine, cyclosporine, or tacrolimus. There were no significant changes in cyclosporine or tacrolimus doses. Mean HbA1C improved from 8.1+/-1.5% to 6.9+/-1.3% (P =0.01) in the 18 patients and from 8.6+/-1.5% to 6.7+/-0.5% (P =0.035) in the 7 patients with posttransplant diabetes. All patients with posttransplant diabetes were well controlled without insulin therapy. CONCLUSIONS: Rosiglitazone is a safe and effective oral agent for the treatment of diabetes mellitus after solid organ transplantation. It is the first agent to allow successful oral therapy for patients with posttransplant diabetes, and is a well-tolerated alternative to insulin for these patients.     

Tacrolimus as a rescue immunosuppressant after heart transplantation.

OBJECTIVE: The purpose of this retrospective study is to review our experience with tacrolimus as a rescue immunosuppressant for heart transplant recipients with refractory rejection or cyclosporine intolerance. METHODS: From June 1995 to November 1998, 15 cardiac transplant recipients were converted from our standard cyclosporine-based immunosuppressive regimen to a tacrolimus-based treatment. Each patient had been treated with cyclosporine, azathioprine and steroids. Six were switched to tacrolimus for persistent rejection, four for recurrent acute rejection and five for severe debilitating side-effects attributed to cyclosporine. All ten patients converted to tacrolimus because of rejection had been treated with high-dose methylprednisolone intravenously and four had also received anti-lymphocyte globulin (ALG; one patient) or anti-thymocyte globulin (ATG; three patients) preparations. RESULTS: The time between transplantation and conversion to tacrolimus ranged from 44 to 1866 (median, 380) days. The range of follow-up after conversion was 84-1379 (median, 806) days. Eleven patients are alive with a follow-up period of 764+/-435 (median, 820) days. Four patients died between 90 and 930 (median, 464) days after conversion. The average number of episodes of acute rejection/recipient decreased from 2.1+/-1.6 on the cyclosporine regimen to 0.2+/-0.4 on the tacrolimus regimen (P<0.001). When the incidence of acute rejection was normalized for follow-up times (episodes/100 patient-days), the results were 1.1+/-1.4 and 0.07+/-0.2, respectively (P<0.01). The persistent/recurrent rejection resolved in all ten patients who were converted to tacrolimus. None of the five cyclosporine intolerant patients converted to tacrolimus experienced rejection after the changeover. CONCLUSIONS: In our experience, conversion from a cyclosporine-based to a tacrolimus-based maintenance immunosuppression has been shown to be an effective and safe approach to the management of patients with persistent or recurrent cardiac allograft rejection or those with cyclosporine intolerance.     

Effects of nonglucose nutrients on insulin secretion and action in people with pre-diabetes

To determine whether nonglucose nutrient-induced insulin secretion is impaired in pre-diabetes, subjects with impaired or normal fasting glucose were studied after ingesting either a mixed meal containing 75 g glucose or 75 g glucose alone. Despite comparable glucose areas above basal, glucose-induced insulin secretion was higher (P < 0.05) and insulin action lower (P < 0.05) during the meal than the oral glucose tolerance test (OGTT) in all subgroups regardless of whether they had abnormal or normal glucose tolerance (NGT). However, the nutrient-induced delta (meal minus OGTT) in insulin secretion and glucagon concentrations did not differ among groups. Furthermore, the decrease in insulin action after meal ingestion was compensated in all groups by an appropriate increase in insulin secretion resulting in disposition indexes during meals that were equal to or greater than those present during the OGTT. In contrast, disposition indexes were reduced (P < 0.01) during the OGTT in the impaired glucose tolerance groups, indicating that reduced glucose induced insulin secretion. We conclude that, whereas glucose-induced insulin secretion is impaired in people with abnormal glucose tolerance, nonglucose nutrient-induced secretion is intact, suggesting that a glucose-specific defect in the insulin secretory pathway is an early event in the evolution of type 2 diabetes.     

Glucose intolerance in the carcinoid syndrome.

We assayed glucose tolerance and insulin secretion in ten patients with metastatic carcinoid tumors and the carcinoid syndrome ("active tumors") and in seven patients with metastatic carcinoid tumors without the carcinoid syndrome ("inactive tumors"). The patients with "active tumors" had elevated serum serotonin levels while the patients with "inactive tumors" had normal serum serotonin levels. Of the ten patients with "active tumors," five had diabetic and three had borderline intravenous glucose disposal rate constants (KG = 0.88 +/- 0.07, M. +/- S.E.M.). Their KG was significantly lower (p less than 0.01) than a group of age-matched normals. All of the patients with "inactive tumors" had normal KG values (KG = 1.67 +/- 0.24). Their KG did not differ from that of age-matched normal subjects. Both groups of carcinoid patients had a comparable decrease in their insulinogenic index. Two days' administration of the serotonin antagonist cyproheptadine (Cypro) to eight of the patients with "active tumors" resulted in a significant increase in the "insulinogenic index" (50%) but a nonsignificant increase in the KG (12%). Administration of p-chlorophenylalanine, a compound that blocks serotonin synthesis, resulted in an increase in both the KG (60%) and the "insulinogenic index" (55%). The insulin half-life (t1/2) of patients with "active tumors" (6.1 +/- 0.4 min.) did not differ from the t1/2 of normal subjects (6.6 +/- 0.4 min.), suggesting that the decreased plasma insulin levels following intravenous glucose were due to impaired insulin secretion rather than accelerated insulin destruction. Seven of the patients received treatment with the antitumor agent streptozotocin (Strepto). The patients received cumulative doses of from 70 to 300 mg. of Strepto per kilogram body weight with no impairment in glucose tolerance or insulin secretion. We conclude that there is high incidence of glucose intolerance (80%) and impaired insulin secretion in patients with the carcinoid syndrome and that serotonin plays a role in producing these alterations.     

Cyclosporine A versus tacrolimus in combination with mycophenolate mofetil and steroids as primary immunosuppression after lung transplantation: one-year results of a 2-center prospective randomized trial

OBJECTIVES: Cyclosporine (INN: ciclosporin) A or tacrolimus have been used mostly in combination with azathioprine as primary immunosuppression after lung transplantation. Benefit or risk deriving from the combination with mycophenolate mofetil are yet unknown. METHODS: In a prospective, 2-center, open randomized trial, the combination of cyclosporine A, mycophenolate mofetil, and steroids was compared with tacrolimus, mycophenolate mofetil, and steroids as primary therapy after primary lung transplantation. All patients underwent induction therapy with rabbit antithymocyte globulin for 3 days. The 2 groups were compared with regard to patient survival, freedom from acute rejection, bronchiolitis obliterans, infectious episodes, and side effects. RESULTS: Between September 1997 and April 1999, 74 lung transplant recipients were randomized to receive either cyclosporine A (n = 37) or tacrolimus (n = 37). Groups were comparable with regard to age, sex, transplant procedure, and cytomegalovirus match. Mean follow-up was 507 +/- 258 and 508 +/- 248 days, respectively. Six- and 12-month survival was similar in both groups (89% vs 84% and 82% vs 71%, respectively; P =.748 at 12 months). Two patients from the cyclosporine A group were retransplanted. Freedom from acute rejection at 6 and 12 months was comparable between groups (46% vs 51% and 35% vs 46%, respectively; P =.774 at 12 months). The mean number of treated acute rejection episodes per 100 patient-days was higher in the cyclosporine A than in the tacrolimus group, but the difference was not statistically significant (0.32 +/- 0.42 vs 0.22 +/- 0.30, respectively; P =.097). Four patients from the cyclosporine A group had to be switched to tacrolimus to control ongoing rejection, whereas no patient from the tacrolimus group had to be switched to cyclosporine A. There was a trend toward more infections (0.7 +/- 0.36 vs 0.55 +/- 0.31, P =.059) in the cyclosporine A group. New-onset diabetes mellitus was observed in the tacrolimus group only (11% vs 0%, P =.151), whereas there was a higher incidence of hypertension (60% vs 11%, P =.03) in the cyclosporine A group. CONCLUSION: This 2-center, prospective randomized study showed high immunosuppressive potency of both cyclosporine A and tacrolimus in combination with mycophenolate mofetil. No significant difference in incidence of acute rejection was observed between the 2 groups. Moreover, survival and incidence of infection were similar. Incidence of drug-related adverse events were similar, yet their spectrum was different.     

Effects of cyclosporine on glucose metabolism

Cyclosporine may have deleterious effects on glucose metabolism. This study was designed to characterize more precisely cyclosporine-induced alterations in glucose homeostasis in a large animal model with hyperglycemic and euglycemic clamp studies in addition to simple bolus glucose (IVGTT) and insulin (IVITT) tolerance tests. In experiment 1, IVGTTs and hyperglycemic clamp studies were performed in eight ewes before and after 4 weeks of cyclosporine treatment. Studies were repeated 4 weeks after cessation of therapy. In experiment 2, IVITTs and euglycemic clamp studies were performed in seven ewes before and after 4 weeks of cyclosporine treatment. Fasting glucose and insulin levels were not affected by cyclosporine treatment. In experiment 1 cyclosporine did not alter IVGTTs; however, during sustained hyperglycemia, cyclosporine caused a 37% decrease in net glucose disposal (p less than 0.001) and a 39% decrease in plateau plasma insulin levels (p less than 0.05). In experiment 2 cyclosporine had no effect on IVITTs. Plateau insulin values in euglycemic clamp studies were lowered by 27% (p less than 0.05) after cyclosporine treatment. In addition, the metabolic clearance rate of insulin was increased by 25% (p less than 0.05), and the steady-state insulin clearance rate was increased by 16% (p less than 0.003). Measurements of insulin sensitivity were unchanged by cyclosporine. These experiments suggest that cyclosporine treatment results in impairment of sustained synthesis and secretion of insulin, increased insulin clearance, and unaltered insulin sensitivity.