Prevalence of impaired glucose metabolism in beta-thalassemic children receiving hypertransfusions with a suboptimal dosage of iron-chelating therapy

Magnetic resonance imaging T2* of the pancreas value using an online software tool and correlate with T2* value of myocardium and liver among patients with transfusion-dependent thalassemia major

Objective

Patients with thalassemia major do require lifetime blood transfusions that eventually result in iron accumulation in different organs. We described the usefulness of using magnetic resonance imaging (MRI) T2^*imaging values for the evaluation of pancreatic iron load in these patients, and we correlated it with MRI T2^* haemosiderosis of the myocardium and liver that has been recognized as a non-invasive assessment of iron overload among patients with thalassemia major.

Materials and methods

We conducted a cross-sectional study on 39 patients with thalassemia major in one of the tertiary university hospitals for a 1-year period. Demographic data were collected from the patient's history. MRI T2^* of the pancreas, liver, and heart were executed on all patients in the same setting. Objective values of iron overload in these organs were obtained using the MRI post-processing software from online software.

Results

A total of 32 (82.1%) patients had pancreatic iron overload including 2 patients (5.1%) with severe iron overload and 15 patients (38.5%) with moderate and mild iron overload, respectively. Nine patients (23.1%) had myocardial iron overload, which included 3 patients (7.7%) who had severe cardiac haemosiderosis. Notably, 37 patients (94.9%) had liver iron overload, which included 15 patients (38.5%) who had severe liver haemosiderosis. There was a moderate positive correlation between the relaxation time of the pancreas and heart haemosiderosis (r = 0.504, P < 0.001). No significant correlation was found between the relaxation time of the pancreas with the liver and the heart with the liver.

Conclusion

Pancreatic haemosiderosis precedes cardiac haemosiderosis, which establishes a basis for initiating earlier iron chelation therapy to patients with thalassemia major.

Long-Term Follow-up of β-Transfusion-Dependent Thalassemia (TDT) Normoglycemic Patients with Reduced Insulin Secretion to Oral Glucose Tolerance Test (OGTT): A Pilot Study

Objective

To study the endocrine pancreas’ function in transfusion-dependent β-thalassemia (β-TDT) patients with a normal glucose tolerance test (NGT) and hypoinsulinemia. In addition, the prospective long–term follow-up using an annual oral glucose tolerance test (OGTT) to detect any abnormality of glucose metabolism.

Patients and methods

Seven β-TDT patients (mean age 22.4 ± 4.2 years) with NGT and inadequate insulin response (hypoinsulinemia) to OGTT were referred for a second opinion to an Italian Centre.

Results

The first-phase insulin response (FPIR), expressed as the sum of 1 and 3 minutes insulin, to intravenous glucose tolerance test (IVGTT), was between the 1^st and 3^rd percentile in two patients and between the 3^rd and 10^th percentile in five. The results were not associated with β-cell autoimmunity. After 43 ± 26 months (range 11 – 80 months) of follow-up, two patients developed impaired glucose tolerance (IGT), three both IGT and impaired fasting glucose (IFG) and two overt diabetes mellitus (DM). Interestingly, the patients who developed DM had, at baseline, the lowest value of the insulinogenic index (IGI: 0.08 and 0.25), defined as the ratio of the increment of plasma insulin to plasma glucose during the first 30 minutes after OGTT. Moreover, a significant correlation was found between the IGI at baseline and at follow-up in the patients who developed IGT with or without IFG (R= 0.927; P: 0.023). A significant reduction of Matsuda insulin sensitivity index (ISIM) and Insulin Secretion-Sensitivity Index-2 (ISSI-2) was documented in the study cohort at the diagnosis of IFG, IGT, and DM. There was a significant inverse correlation between ISSI-2 and area under the curve plasma glucose (AUC-PG).

Conclusions

These data demonstrated, for the first time, progressive deterioration in glucose homeostasis in β-TDT subjects with NGT and hypoinsulinemia and that the ISSI-2 index may be a valuable parameter to identify patients at high risk for developing glucose dysregulation.

A mitophagic response to iron overload-induced oxidative damage associated with the PINK1/Parkin pathway in pancreatic beta cells

BACKGROUND

Iron overload can result in a disorder in glucose metabolism. However, the underlining mechanism through which iron overload induces beta cell death remains unknown.

METHODS

According to the concentration of ferric ammonium citrate (FAC) and N-acetylcysteine, INS-1 cells were randomly divided into four groups: normal control (FAC 0 μM) group, FAC 80 μM group, FAC 160 μM group, FAC 160μM + NAC group. Cell proliferation was assessed by Cell Counting Kit-8. Reactive oxygen species (ROS) level was further evaluated using flow cytometer with a fluorescent probe. The mitochondrial membrane potential was detected by JC-1 kit, and transmission electron microscopy was used to observe the mitochondrial changes. The related protein expressions were detected by western bolt to evaluate mitophagy status.

RESULTS

It was shown that FAC treatment decreased INS-1 cell viability in vitro, resulted in a decline in mitochondrial membrane potential, increased oxidative stress level and suppressed mitophagy. Furthermore, these effects could be alleviated by the ROS scavenger.

CONCLUSIONS

We proved that increased iron overload primarily increased oxidative stress and further suppressed mitophagy via PTEN-induced putative kinase 1/Parkin pathway, resulting in cytotoxicity in INS-1 cells.

Early development of decreased β-cell insulin secretion in children and adolescents with hemoglobin H disease and its relationship with levels of anemia

BACKGROUND

Diabetes mellitus (DM) associated with iron overload has been reported among adults with transfusion-dependent thalassemia and those with non-transfusion-dependent thalassemia (NTDT), especially in β-thalassemia disease. However, little is known about glucose metabolism and how early its dysregulation can develop in α-thalassemia hemoglobin H (Hb H) disease, which is one of the most common types of NTDT worldwide.

PROCEDURE

We prospectively calculated glucose metabolism index in 40 patients (aged 10-25 years) with Hb H disease. Glucose metabolism data were compared between patients with deletional versus nondeletional Hb H, and between patients with normal versus abnormal insulin secretion/sensitivity.

RESULTS

Despite normal glucose tolerance in all patients, 52.5% had abnormal insulinogenic index indicating decreased β-cell insulin secretion. Patients with functional hemoglobin < 8 g/dL had significantly higher percentages of abnormal insulinogenic index. There was no significant difference in abnormal insulinogenic index between deletional and nondeletional Hb H.

CONCLUSION

Decreased β-cell insulin secretion is highly prevalent among children and adolescents with Hb H disease, and it is associated with levels of functional anemia at baseline, but not with the type of Hb H disease. This result warrants heightened awareness among hematologists due to potentially increased risk of DM later in life.

Elevated Prevalence of Abnormal Glucose Metabolism and Other Endocrine Disorders in Patients with β-Thalassemia Major: A Meta-Analysis

Background

Endocrinopathies are common in patients with β-thalassemia major despite parenteral iron chelation therapy with deferoxamine. Prevalence of abnormal glucose metabolism in previous studies was controversial. The aim of this study was to discuss the prevalence of abnormal glucose metabolism in β-thalassemia major based on a meta-analysis.

Methods

PubMed, ScienceDirect, Springerlink, Ovid, Web of Science, MEDLINE, Wanfang database, and Chinese National Knowledge Internet were searched for relevant articles. Two authors selected the articles according to the inclusion criteria and then extracted the data. The prevalence of diabetes mellitus (DM) in β-thalassemia major was defined as the primary outcome. The prevalence with the 95% confidence interval (95%CI) was used to evaluate the proportion of abnormal glucose metabolism and other endocrine disorders in patients with β-thalassemia major. Subgroup analyses were applied to explore the prevalence in different regions. Sensitivity analysis and publication bias assessment were also conducted.

Results

A total of 44 studies with 16605 cases were included in this analysis. Diabetes mellitus was present in 6.54% (95% CI: 5.30%-7.78%). The fixed subgroup study revealed that the region with the highest prevalence was the Middle East (prevalence= 7.90%, 95% CI: 5.75%-10.05%). The accumulated meta-analysis revealed that the prevalence of DM in β-thalassemia major was relatively steady in each year. The prevalence of impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and other endocrine disorders in β-thalassemia major was 17.21% (95% CI: 8.43%-26.00%), 12.46% (95% CI: 5.98%-18.94%), and 43.92% (95% CI: 37.94%-49.89%), respectively. Sensitivity analysis showed that the pooled results were robust; publication bias assessment revealed that there was no significant evidence that the pooled results were influenced by publication bias.

Conclusion

High prevalence of endocrine disorders involving abnormal glucose metabolism was detected in β-thalassemia major. Treatment and prevention measurements may be necessary to prevent growth and endocrine problems.

Prenatal iron exposure and childhood type 1 diabetes

Iron overload due to environmental or genetic causes have been associated diabetes. We hypothesized that prenatal iron exposure is associated with higher risk of childhood type 1 diabetes. In the Norwegian Mother and Child cohort study (n = 94,209 pregnancies, n = 373 developed type 1 diabetes) the incidence of type 1 diabetes was higher in children exposed to maternal iron supplementation than unexposed (36.8/100,000/year compared to 28.6/100,000/year, adjusted hazard ratio 1.33, 95%CI: 1.06-1.67). Cord plasma biomarkers of high iron status were non-significantly associated with higher risk of type 1 diabetes (ferritin OR = 1.05 [95%CI: 0.99-1.13] per 50 mg/L increase; soluble transferrin receptor: OR = 0.91 [95%CI: 0.81-1.01] per 0.5 mg/L increase). Maternal but not fetal HFE genotypes causing high/intermediate iron stores were associated with offspring diabetes (odds ratio: 1.45, 95%CI: 1.04, 2.02). Maternal anaemia or non-iron dietary supplements did not significantly predict type 1 diabetes. Perinatal iron exposures were not associated with cord blood DNA genome-wide methylation, but fetal HFE genotype was associated with differential fetal methylation near HFE. Maternal cytokines in mid-pregnancy of the pro-inflammatory M1 pathway differed by maternal iron supplements and HFE genotype. Our results suggest that exposure to iron during pregnancy may be a risk factor for type 1 diabetes in the offspring.

Insulin Secretion and Resistance in Normoglycemic Patients with Sickle Cell Disease

Diabetes mellitus has been described in chronic hemolytic anemias, but data are scarce regarding glucose metabolism in normoglycemic patients. To address this issue, we evaluated insulin sensitivity and secretion in patients with sickle cell disease (SCD) and normal oral glucose tolerance test (OGTT). Forty-five adult patients with homozygous sickle cell disease and Hb S/β-thalassemia (β-thal) (mean age 42.5 ± 9.5 years) and 45 healthy individuals matched for age and body mass index (BMI) were included in the study. All participants underwent an oral glucose tolerance test (OGTT) after an overnight fast. All patients had normal OGTT. Fasting glucose values did not differ significantly between groups, however, fasting insulin levels were significantly lower in the patient group compared to the control group (5.1 ± 2.7 μUI/mL vs. 11.3 ± 6.6 μUI/mL, p <0.005, respectively). Pancreatic β-cell insulin secretion index in the fasting state was significantly lower in patients with sickle cell disease compared with controls as assessed by calculations of the homeostatic model assessment for β-cell function (HOMA β%) (77.0 vs. 106.0%, respectively, p <0.001), while HOMA insulin resistance (HOMA IR), was lower in the sickle cell disease patients, albeit not statistically significant (0.8 vs. 1.1, respectively, p = 0.054). The HOMA β% was significantly correlated with ferritin levels (r = -526, p <0.001) (negative correlation) and with 25-hydroxy (OH)-vitamin D levels (r = 0.479, p <0.001) (positive correlation), even when adjusted for serum ferritin levels. Normoglycemic patients with sickle cell disease demonstrated impaired β-cell function with reduced insulin secretion even before OGTT was impaired.

Effect of long-term transfusion therapy on the glycometabolic status and pancreatic Beta cell function in patients with Beta thalassemia major

BACKGROUND

Diabetes mellitus is a major complication of iron overload in patients with beta thalassemia major.

DESIGN

This is a descriptive study conducted in a Tertiary Care Teaching Hospital to analyze beta cell function and insulin resistance, and their relation to iron overload status in beta thalassemia major. Fasting glucose, two-hour post load glucose, fasting insulin, alanine amino transaminase (ALT), and ferritin were used as outcome measures. The homeostatic model assessment (HOMA model) was used to calculate the beta cell function and insulin resistance index.

RESULTS

Of the 30 cases, 20% had impaired fasting glucose, 3.3% had impaired glucose tolerance, and none had diabetes. Fasting glucose was not significant between the cases and controls (P = 0.113). Fasting insulin (P = 0.001), ferritin (P = 0.001), and ALT (P = 0.001) levels were significantly high in the cases. Insulin resistance index was significantly higher in the cases (P = 0.001) as also the beta cell function (P = 0.001). With increase in age and the number of units transfused there is a decline in beta cell function, fasting insulin, and insulin resistance after attaining the maximum level. This suggests that initial insulin resistance is followed by insulin depletion due to loss of beta cell function, leading to diabetes mellitus.

CONCLUSION

Impaired glucose tolerance (IGT) and insulin resistance precede the onset of insulin-dependent diabetes and adequate chelation therapy is essential for delaying the onset or for prevention of diabetes.

Effect of splenectomy on iron balance in patients with β-thalassemia major: a long-term follow-up

OBJECTIVE

A retrospective study was performed to explore the effect of splenectomy on iron balance in thalassemia major (TM).

METHODS

Twenty two TM patients treated with splenectomy were compared with a control group (non-splenectomized patients) matched for sex, age, pretransfusional Hb, chelation therapy, and duration of follow-up in a retrospective study to evaluate blood consumption, iron intake, and serum ferritin during an overall observation period of 6 yrs before and 10 yrs after splenectomy.

RESULTS

Splenectomy improved parameters of iron balance, determining a significant reduction in blood consumption (P < 0.01), iron intake (P < 0.01), and serum ferritin (P < 0.01). Comparing the two groups, blood consumption and iron intake were similar in presplenectomy period (P > 0.05), but serum ferritin was significantly higher in splenectomized patients (P < 0.01). After splenectomy, blood consumption and iron intake were significantly lower (P < 0.01) in splenectomized group while serum ferritin did not differ significantly (P > 0.05) between two groups, except for the first year (P < 0.05).

CONCLUSION

Splenectomy determines immediate drop in blood consumption and iron intake but slow downtrend of ferritin; direct measurements of iron overload, such as magnetic resonance studies, are needed to better understand the effect of splenectomy on iron balance parameters. Tailoring chelation therapy and eventually its intensification seem more efficient measures to manage iron accumulation in TM and to lower iron level to safety threshold.

Iron and diabetes risk

Iron overload is a risk factor for diabetes. The link between iron and diabetes was first recognized in pathologic conditions-hereditary hemochromatosis and thalassemia-but high levels of dietary iron also impart diabetes risk. Iron plays a direct and causal role in diabetes pathogenesis mediated both by β cell failure and insulin resistance. Iron also regulates metabolism in most tissues involved in fuel homeostasis, with the adipocyte in particular serving an iron-sensing role. The underlying molecular mechanisms mediating these effects are numerous and incompletely understood but include oxidant stress and modulation of adipokines and intracellular signal transduction pathways.

Pancreatic iron and glucose dysregulation in thalassemia major

Pancreatic iron overload and diabetes mellitus (DM) are common in thalassemia major patients. However, the relationship between iron stores and glucose disturbances is not well defined. We used a frequently sampled oral glucose tolerance test (OGTT), coupled with mathematical modeling, and magnetic resonance imaging (MRI) to examine the impact of pancreatic, cardiac, and hepatic iron overload on glucose regulation in 59 patients with thalassemia major. According to OGTT results, 11 patients had DM, 12 had impaired glucose tolerance (IGT), 8 had isolated impaired fasting glucose (IFG), and 28 patients had normal glucose tolerance (NGT). Patients with DM had significantly impaired insulin sensitivity and insulin release. Insulin resistance was most strongly associated with markers of inflammation and somatic iron overload, while disposition index (DI) (a measure of beta cell function) was most strongly correlated with pancreas R2*. Patients with DM and IGT had significantly worse DI than those with NGT or IFG, suggesting significant beta cell toxicity. One-third of patients having elevated pancreas R2* had normal glucose regulation (preclinical iron burden), but these patients were younger and had lower hepatic iron burdens. Our study indicates that pancreatic iron is the strongest predictor of beta cell toxicity, but total body iron burden, age, and body habitus also influence glucose regulation. We also demonstrate that MRI and fasting glucose/insulin are complementary screening tools, reducing the need for oral glucose tolerance testing, and identify high-risk patients before irreversible pancreatic damage.

Oral chelators in transfusion-dependent thalassemia major patients may prevent or reverse iron overload complications

Combined chelation treatment may be a better approach for transfusion-dependent thalassemia major patients with iron overload complications because of increased efficacy. Combination therapy with desferrioxamine and deferiprone has already been reported to improve survival dramatically by reversing cardiac dysfunction and other endocrine complications. Some patients have intolerance or inconvenience to parenteral desferrioxamine. The hypothesis of this study was that combining two oral chelators, deferiprone and deferasirox, might lead to similar results. Following approval by the hospital ethical committee and a written informed consent from each patient, 16 patients who fulfilled the criteria participated in a study protocol for a period of up to 2 years. Efficacy measures analysis demonstrated a statistically significant decrease of total body iron load as estimated by serum ferritin, LIC and MRI T2* indices. Regarding the safety assessment, the incidence of adverse events was minor compared to the associated toxicity of monotherapy of each drug. No new onset of iron overload-related complications was demonstrated. A reversal of cardiac dysfunction was observed in 2/4 patients, while the mean LVEF increased significantly. Regarding endocrine assessment, in 2/8 patients with impaired glucose tolerance, we noted a significant decrease in the mean 2h glucose in OGTT. Additionally an improvement in gonadal function was observed and one male and one female gave birth to two healthy children without hormonal stimulation. Combined oral chelation in thalassemia offers the promise of easier administration, better compliance and may lead to an improvement of patient quality of life by preventing or even reversing iron overload complications.