Edmond A. Ryan

Islet Transplantation in Seven Patients with Type 1 Diabetes Mellitus Using a Glucocorticoid-Free Immunosuppressive Regimen

BACKGROUND Registry data on patients with type 1 diabetes mellitus who undergo pancreatic islet transplantation indicate that only 8 percent are free of the need for insulin therapy at one year. METHODS Seven consecutive patients with type 1 diabetes and a history of severe hypoglycemia and metabolic instability underwent islet transplantation in conjunction with a glucocorticoid-free immunosuppressive regimen consisting of sirolimus, tacrolimus, and daclizumab. Islets were isolated by ductal perfusion with cold, purified collagenase, digested and purified in xenoprotein-free medium, and transplanted immediately by means of a percutaneous transhepatic portal embolization. RESULTS All seven patients quickly attained sustained insulin independence after transplantation of a mean (+/-SD) islet mass of 11,547+/-1604 islet equivalents per kilogram of body weight (median follow-up, 11.9 months; range, 4.4 to 14.9). All recipients required islets from two donor pancreases, and one required a third transplant from two donors to achieve sustained insulin independence. The mean glycosylated hemoglobin values were normal after transplantation in all recipients. The mean amplitude of glycemic excursions (a measure of fluctuations in blood glucose concentrations) was significantly decreased after the attainment of insulin independence (from 198+/-32 mg per deciliter [11.1+/-1.8 mmol per liter] before transplantation to 119+/-37 mg per deciliter [6.7+/-2.1 mmol per liter] after the first transplantation and 51+/-30 mg per deciliter [2.8+/-1.7 mmol per liter] after the attainment of insulin independence; P<0.001). There were no further episodes of hypoglycemic coma. Complications were minor, and there were no significant increases in lipid concentrations during follow-up. CONCLUSIONS Our observations in patients with type 1 diabetes indicate that islet transplantation can result in insulin independence with excellent metabolic control when glucocorticoid-free immunosuppression is combined with the infusion of an adequate islet mass.

Insulin action during pregnancy. Studies with the euglycemic clamp technique

To assess the mechanisms responsible for the insulin resistance associated with both normal human pregnancy and gestational-onset diabetes, we have measured exogenous glucose disposal using sequential insulin infusions with the euglycemic glucose clamp technique and erythrocyte insulin binding. Three groups of women were studied: nonpregnant women with normal glucose tolerance (N = 7, mean age 32.9 ± 2.1 yr), pregnant women with normal glucose tolerance (N = 5, mean age 24.8 ± 3.5 yr), and pregnant women with gestational-onset diabetes (N = 5, mean age 34.6 ± 2.6 yr). Despite normal plasma glucose levels obtained during a 100-g oral glucose tolerance test, plasma insulin levels were significantly elevated in the pregnant women compared with the nonpregnant control subjects, suggesting a state of insulin resistance. Insulin binding to erythrocytes was similar in all three groups (maximum specific binding being 5.0 ± 0.6%, 5.5 ± 1.1%, and 6.0 ± 0.7% in nonpregnant, nondiabetic pregnant, and gestational-onset diabetic women, respectively). In vivo peripheral insulin action was measured using the euglycemic glucose clamp technique during an insulin infusion of 40 mil/ m2 · min, with blood glucose clamped at a concentration of 75 mg/dl using a variable glucose infusion. Glucose infusion rates were 213 ± 11 mg/m2 min, 143 ± 23 mg/m2 · min, and 57 ± 18 mg/m2 · min in nonpregnant, nondiabetic pregnant, and gestationalonset diabetic women, respectively. This demonstrates that pregnant subjects display a state of insulin resistance, and that this appears to be more marked in gestational-onset diabetic subjects. To further define the possible mechanism of insulin resistance during pregnancy, the insulin infusion rate was increased to 240 mU/m2 · min and further euglycemic clamp measurements performed. Glucose infusion rates were 372 ± 11 mg/m2 · min, 270 ± 31 mg/m2 · min, and 157 ± 26 mg/m2 · min, in nonpregnant, nondiabetic pregnant, and gestational-onset diabetic women, respectively. This demonstrates a shift to the right of the dose-response curve of insulin action and suggests that the insulin resistance of pregnancy may include a decrease in presumed “maximum” insulin responsivity. In four subjects, studies were repeated in the postpartum period, and these demonstrated that the insulin resistance of pregnancy is ameliorated shortly after delivery. These studies suggest that the insulin resistance of pregnancy results from a target cell defect in insulin action beyond the initial step of insulin binding to cellular receptors, a postreceptor (or postbinding) defect in insulin action.

Long-term follow-up after transplantation of insulin-producing pancreatic islets into patients with Type 1 (insulin-dependent) diabetes mellitus

SummaryPurified human islets and a kidney from the same donor were transplanted into four patients with Type 1 (insulin-dependent) diabetes mellitus. Two of the patients received additional islets that were isolated from multiple donors, cryopreserved, and stored in a tissue bank. The islets were embolized into the liver via the portal vein. Immunosuppression was induced with antilymphocyte globulin and maintained with azathioprine, prednisone and cyclosporine. In the first two patients, fasting serum C-peptide rose to levels of 0.5–2.0 ng/ml during the first 4–8 weeks and mixed meal feeding elicited increases to 2–3 ng/ml. C-peptide secretion persisted for 8 months, but at progressively lower levels and insulin therapy could not be withdrawn. In the next two patients who received cryopreserved islets in addition to fresh islets, serum C-peptide levels (fasting/post-meal) rose to 4–7 ng/ml and serum glucose was more stable, allowing withdrawal of insulin therapy after 69 days in one patient, and reduced insulin doses in the other. The insulin-independent patient has maintained normal fasting glucose, glycosylated haemoglobin, and oral glucose tolerance at 1 year following cessation of daily insulin therapy. Episodes of renal graft rejection occurred in three patients, including the insulin-independent patient. High-dose steroid therapy reversed the rejection in all instances, with apparent preservation of C-peptide secretion. These data show that transplantation of purified freshly-prepared and cryopreserved islets into Type 1 diabetic patients results in prolonged insulin secretion, and that sufficient function could be provided in one patient to sustain euglycaemia in the absence of insulin therapy at 1 year of follow-up.

Normoglycaemia after transplantation of freshly isolated and cryopreserved pancreatic islets in Type 1 (insulin-dependent) diabetes mellitus

SummaryPurified islets of Langerhans and a kidney were transplanted into a 36-year-old patient who suffeded from renal failure secondary to a 25 year history of Type 1 (insulin-dependent) diabetes mellitus. The islet graft contained 243 000 fresh islets (mean islet diameter 150 μm) that were syngeneic with the kidney fraft and 368 000 cryopreserved islets that had been collected from four other donors. The total of 10 000 islets/kg body weight was infused into the liver via the umbilical vein. Immunosupperession was induced with antilymphocyte globulin and maintained with prednisone, cyclosporine and azathioprine. Serum C-peptide levels (ng/ml) during fasting and after standard mixed metal feeding (Sustacal) were <0.12 preoperatively. Postoperatively, insulin secretion was restored: fasting C-peptide rose during the first 4 weeks to levels of 4 to 5 and Sustacal elicited a further rise to 6 to 7. Transplant renal function was stable. Dialy fasting glucose (mmol/l, mean±SD) was 5.6±1 and 5.3±0.6 during the first and second months respectively and post-Sustacal glucose was 5.7+-0.8. Exogenous insulin therapy was progressively withdrawn and stopped duting the ninth week. Thereafter, fasting glucose was 4.7+-0.5, 24 h mean glucose was 6.6+-0.5, and normoglycaemia was maintained after Sustacal. These data show that this mass of freshly isolated and cryopreserved islets from multiple donors provided sustained function (3 months) that reversed insulin-dependence in an immunosuppressed Type 1 diabetic patient treated with simultaneous islet-kedney transplantation.

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) ≥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.

Defects in Insulin Secretion and Action in Women With a History of Gestational Diabetes

Gestational diabetes mellitus (GDM) is associated with defects in insulin secretion and insulin action, and women with a history of GDM carry a high risk for the development of non-insulin-dependent diabetes mellitus (NIDDM). Assessment of subjects with a history of GDM who are currently normoglycemic should help elucidate some of the underlying defects in insulin secretion or action in the evolution of NIDDM. We have studied 14 women with normal oral glucose tolerance who had a history of GDM. They were compared with a group of control subjects who were matched for both body mass index (BMI) and waist-to-hip ratio (WHR). All subjects underwent tests for the determination of oral glucose tolerance, ultradian oscillations in insulin secretion during a 28-h glucose infusion, insulin secretion in response to intravenous glucose, glucose disappearance after intravenous glucose (Kg), and insulin sensitivity (SI) as measured by the Bergman minimal model method. The BMI in the post-GDM women was similar to that in the control subjects (24.9 ± 1.2 vs. 25.4 ± 1.4 kg/m2, respectively), as was the WHR ratio (0.80 ± 0.01 vs. 0.76 ± 0.01, respectively). The post-GDM women were slightly older (35.2 ± 0.9 vs. 32.1 ± 1.4 years, P = 0.04). The fasting plasma glucose levels were significantly higher in the post-GDM group than in the control group (4.9 ± 0.1 vs. 4.4 ± 0.1 mmol/l, respectively, P < 0.001) and remained higher at each of the subsequent determinations during the oral glucose tolerance test, although none had a result indicative of either diabetes or impaired glucose tolerance. All measures of ultradian insulin secretory oscillations in post-GDM subjects were indistinguishable from those in the control subjects. The first-phase insulin release to intravenous glucose was lower in the post-GDM group. SI was also impaired in the post-GDM group compared with the control subjects (4.6 ± 0.5 vs. 6.8 ± 1.0·10−4·min−1· ³U−1·ml, respectively, P < 0.05). Kg was reduced in the post-GDM women compared with the control subjects (1.3 ± 0.1 vs. 2.7 ± 0.4%, P < 0.01). When the subjects were divided according to their BMI, lean post-GDM subjects (<24.2, n = 8) were more insulin resistant than the lean control subjects: SI 5.3 ± 0.6 vs. 8.8 ± 1 · 1·10−4 min −1· ³U−1·ml, P = 0.02, whereas obese post-GDM (>24.2 kg/m2, n = 6) and control subjects had a lower SI than the lean subjects, but they were not different from each other (3.6 ± 0.7 vs. 4.2 ± 1.2· 10−4· min−1 · ³U−1 · ml, respectively, P = 0.67). The acute insulin responses to glucose (0–10 min) within these groups showed that the lean post-GDM group had a significantly lower insulin response compared with control subjects (1,205 ± 179 vs. 2,404 ± 416 pmol· 1−1 min, respectively, P = 0.007), whereas the obese groups had similar responses (2,777 ± 1,112 vs. 3,114 ± 847 pmol ·1−·min, post-GDM vs. control subjects, P = 0.8). We have found defects in insulin secretion and action in post-GDM subjects who are at high risk for the development of NIDDM at a time that oral glucose tolerance is normal. These defects are present in the absence of obesity. Ultradian insulin secretory oscillations during constant glucose infusion are normal in these post-GDM subjects predisposed to NIDDM. We conclude that defects in both insulin secretion and insulin action are present before the development of hyperglycemia in women with a history of GDM.

Diagnosing gestational diabetes

The newly proposed criteria for diagnosing gestational diabetes will result in a gestational diabetes prevalence of 17.8%, doubling the numbers of pregnant women currently diagnosed. These new diagnostic criteria are based primarily on the levels of glucose associated with a 1.75-fold increased risk of giving birth to large-for-gestational age infants (LGA) in the Hyperglycemia Adverse Pregnancy Outcome (HAPO) study; they use a single OGTT. Thus, of 23,316 pregnancies, gestational diabetes would be diagnosed in 4,150 women rather than in 2,448 women if a twofold increased risk of LGA were used. It should be recognised that the majority of women with LGA have normal glucose levels during pregnancy by these proposed criteria and that maternal obesity is a stronger predictor of LGA. The expected benefit of a diagnosis of gestational diabetes in these 1,702 additional women would be the prevention of 140 cases of LGA, 21 cases of shoulder dystocia and 16 cases of birth injury. The reproducibility of an OGTT for diagnosing mild hyperglycaemia is poor. Given that (1) glucose is a weak predictor of LGA, (2) treating these extra numbers has a modest outcome benefit and (3) the diagnosis may be based on a single raised OGTT value, further debate should occur before resources are allocated to implementing this change.

Resistance exercise decreases the need for insulin in overweight women with gestational diabetes mellitus

OBJECTIVE This study examines the effects of circuit-type resistance training on the need for insulin in women with gestational diabetes mellitus. STUDY DESIGN Thirty-two patients with gestational diabetes mellitus were randomly assigned either to a group that was treated with diet alone or to a group that was treated with diet plus resistance exercise. RESULTS The number of women whose condition required insulin therapy was the same, regardless of treatment. However, a subgroup analysis that examined only overweight women (prepregnant body mass index, >25 kg/m(2)) showed a lower incidence of insulin use in the diet-plus-exercise group (P<.05). Women in the diet-plus-exercise group were prescribed less insulin (P<.05) and showed a longer delay from diagnosis to the initiation of insulin therapy (P<.05), compared with the diet-alone group. CONCLUSION Resistance exercise training may help to avoid insulin therapy for overweight women with gestational diabetes mellitus.

Portal venous pressure changes after sequential clinical islet transplantation.

Background. Sequential pancreatic islet transplantation via the portal vein has led to insulin independence in patients with type 1 diabetes. Complications associated with the injection of islets into the portal vein have been reported; therefore, in this study we sought to further characterize changes in portal venous pressure associated with islet infusion. Methods. Pre- and posttransplant portal venous pressures were recorded in 50 consecutive transplant procedures in 26 patients receiving highly purified, heparinized allogeneic islet preparations via a radiologically placed portal venous cannula. Doppler ultrasound scans of the portal vein were completed within 24 hr of transplantation. Results. Posttransplant portal vein pressures rose significantly with sequential transplantation (12.4 mm Hg vs. 17.3 mm Hg, P <0.05). Portal pressure change correlated significantly with islet packed cell volume (r =0.66, P <0.001) and also with the number of islets transplanted (r =0.49, P <0.001). Segmental portal vein thrombosis was radiologically detected after two procedures (4%). Conclusion. Multiple sequential islet transplants can be safely performed via the portal vein, provided that care is taken with islet purification and attention is paid to portal venous monitoring.

Variation of Postprandial Plasma Glucose, Palatability, and Symptoms Associated With a Standardized Mixed Test Meal Versus 75 g Oral Glucose

OBJECTIVE To compare within-subject variability of plasma glucose measured 2 h after a glucose tolerance test (GTT) with that of plasma glucose measured 2 h after administration of a standardized test meal (diabetes screening product [DSP], Ceapro, Edmonton, Alberta, Canada) and to determine the relationship between the two sets of plasma glucose measurements. RESEARCH DESIGN AND METHODS Plasma glucose and insulin responses of 36 overnight-fasted subjects (10 lean normal, 9 obese normal, 9 with impaired glucose tolerance [IGT], and 8 with mild diabetes) were studied on eight different mornings after they consumed 75 g oral glucose or 50 g carbohydrate from the DSP. Each test meal was repeated four times by each subject. Within-subject coefficients of variation (CVs) (CV = 100 × SD/mean) of plasma glucose concentrations 2 h after administration of the GTT and DSP were compared by repeated measures ANOVA and linear regression analysis. RESULTS Mean plasma glucose 2 h after administration of the DSP (D) was linearly related to that 2 h after the GTT (G): G = 1.5 × D − 1.6 (r = 0.97, P < 0.0001). The CV of 2-h plasma glucose was significantly lower after administration of the DSP, 10.5 ± 1.0%, than after the GTT, 12.7 ± 1.18% (P = 0.025). The effect of test meal on CV differed in different groups of subjects (P = 0.018), with the largest difference found in IGT subjects, in whom the CV after DSP administration was 47% < after the GTT (P = 0.0005). The DSP was significantly more palatable and produced fewer adverse symptoms than the GTT. CONCLUSIONS Plasma glucose concentrations measured 2 h after DSP administration are closely related to those measured 2 h after the GTT but are more consistent than the 2-h post-GTT concentrations within the critical IGT range. This finding suggests that measurement of plasma glucose 2 h after administration of the DSP may allow more precise discrimination among normal glucose levels, IGT, and diabetes than measurement of plasma glucose 2 h after the GTT.