الفهرس 
THALASSEMIAOnly 14 pages are availabe for public view
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Abstract
Background: Glucose metabolism disturbances, among other endocrinopathies, are a common feature of β-thalssemia major (β-TM). Pancreatic iron overload and diabetes mellitus (DM) are common in β-TM patients. However, the relationship between iron stores and glucose disturbances is not well defined. Continuous glucose monitoring (CGM) system enables more diagnostic accuracy and a better achievement of an optimal glycemic control. Aim: To assess the pattern of glucose homeostasis in patients with β-TM and detect early impairment in glucose metabolism and prediabetic state in β-thalassemia patients comparing oral glucose tolerance test (OGTT) and CGM system. In addition, we sought to compare standard insulin therapy and insulin pump therapy among TM patients with DM. Methods: This cross sectional study was conducted on 200 patients β-TM patients. Patients were studied focusing on transfusion history, transfusion index, iron chelation therapy and compliance to chelation. Complete blood picture, markers of hemolysis, serum ferritin and random blood glucose (RBG) were measured. Patients with RBG ≥140 mg/dL were subjected to OGTT, insertion of CGMS for 3 days, measurement of fasting C peptide, and serum insulin with calculation of (HOMA-IR) and assessment of HbA1c%. Insulin pump was tried on two of diabetic TM patient compared with conventional insulin therapy. Results: Screening with RBG revealed that 20 patients (10%) had RBG ≥140mg/dL. Using OGTT, 7 (3.5%) patients were in the diabetic range, 7 (3.5%) had normal OGTT while 6 (3%) had impaired glucose tolerance. Only one patient had impaired FBG (135mg/dL). The CGMS showed that 7 (3.5%) patients had IGTT (6.5%) and 13 patients had diabetes mellitus. The percentage of diabetic patients diagnosed by CGMS was significantly higher than that with OGTT (P= 0.012). Ten of the 13 (6.5-9.9%) studied patients with diabetes according to the CGMS readings had abnormal HbA1c readings of diabetic range while 5 of the 7 studied patients with impaired glucose tolerance according to the CGMS had HbA1c readings in the prediabetic range (5.5-6.1%). It was noted that 60% of patients on combined chelation therapy had RBG≥140mg/dL and 85% of patients with RBG≥ 140mg/dL were noncompliant. Also, it was found that 75% of patients on desferrioxamine therapy had RBG≥140mg/dL. Serum ferritin were significantly higher among patients with RBG≥140mg/dl (P= 0.001). In addition, 70% of patients with RBG≥140mg/dL had serum ferritin ≥2500 µg/L. A total of 76.1% of noncompliant TM patients had serum ferritin ≥2500mg/dL and 6% had RBG ≥200mg/dL. All patients with DM according to the OGTT were noncompliant to therapy. There was a significant positive correlation between HbA1C% and FBG among the studied thalassemia patients with elevated RBG≥ 140mg/dL, while HbA1C% was negatively correlated with fasting C-peptide. Serum ferritin was positively correlated with RBG. As regards CGMS data, HbA1C was positively correlated to maximum blood glucose, average blood glucose, SDS blood glucose and AUC≥140mg/dL. The only significant independent factor for elevated RBG ≥140 mg/dL was serum ferritin. Mean blood glucose levels per day were higher in those on subcutaneous insulin than on insulin pump. Conclusions: The use of CGMS in the diagnosis of early glycemic abnormalities (prediabetes) among patients with β-TM appears to be promising and superior to other known diagnostic modalities namely OGTT and HbA1c. Insulin pump has provided better glycemic control to diabetic TM patients compared to the traditional methods of insulin therapy.