Abstract
The most accurate method with which to evaluate altered glucose metabolism in patients with TM is still controversial. Even if the annual oral glucose tolerance test (OGTT) by the age of 10 years is the recommended method, a diagnosis of 'normal' glucose tolerance during OGTT does not exclude abnormal postprandial glucose levels at home . There is now evidence that the OGTT method, evaluating fasting and 2-h post load glucose, may miss episodes of hyperglycaemia . Furthermore, the credibility of Hb A1c has been questioned because the hemoglobin composition of patients' erythrocytes are considerably modified, due to regular and frequent transfusions. The results may be falsely increased or decreased depending on the proximity to transfusion, shortened erythrocyte lifespan and the assay used . It has been demonstrated recently that the continuous glucose monitoring system (CGMS) is a useful and valid tool in defining glucose metabolism in children and adults affected by TM with early glucose derangements . Indeed, the CGMS allows monitoring of glycaemic profiles throughout a period of 72 h for a total of 288 glycaemic registrations per day. It identifies glycaemic excursions and constitutes a valid device to understand the 24-h glycaemic trend and profiles. Rimondiet al. investigated the value of using CGMS in six TM patients with abnormal glucose homeostasis after an oral glucose tolerance test (OGTT) . Two-hour OGTT glucose values and CGMS fluctuations were classified as normal if < 7.8 mmol/l, impaired if 7.8 to 11.1 mmol/l, diabetic if > 11.1 mmol/l. The TM patients spent from 1 to 23% of the time with a blood glucose level from 7.8 to 11.1 mmol/l. we evaluate three patients with Beta Thalassemai major using CGMS
Patient 1 A 15 year old male with TM presented with nocturia. His FBG was 5.6 mmol/L and OGTT showed a BG level at 2hrs of 8.5 mmol/l. His CGMS showed a diabetic range of BG after dinner and overnight. Based on this tracing, a basal insulin (Glargine) was prescribed at night. A satisfactory response was recorded by CGMS .
Patient 2 A 14 year old girl with TM with no symptoms related to glycemic abnormalities. Her FBG was 4.9 mmol/L and an OGTT showed a BG level at 2 hrs of 6.9 mmol/L (IGT). CGMS tracing showed prolonged persistent hyperglycemia after lunch suggesting a need for prandial insulin to cover her carbohydrate load. Insulin aspart before lunch properly controlled her glycemia . Patient 3 A 13 year old boy with TM had a normal FBG (4.5 mmol/L) and OGTT (2h BG =7.6 mmo/l). Applying CGMS monitoring showed IGT state. Furthermore, the effect of packed red cell transfusion showed marked reduction of his BG before meals and overnight. This is the first case to document the rapid beneficial effect of blood transfusion on glycemia in patiens with Beta thalssemia Major Advances in TM care have led to improved survival and quality of life in patients with TM; however, many chronic endocrine diseases have emerged as a result of potential endocrine complications by routine screening and a high index of suspicion is imperative for patients with TM to receive timely treatment.Our results demonstrate that the CGMS is a useful method to detect the variability of glucose fluctuations and offers the opportunity for better assessment of glucose homeostasis in TM patients. Proper and early iron chelation or the use of intensive iron chelation in those with high iron load the new oral chelators have been shown to decrease or reversethese glycemic abnormalities.In addition, optimization of insulin therapy with the help of CGMS appears to be clinically useful and costeffective approach.
No relevant conflicts of interest to declare.
Author notes
Asterisk with author names denotes non-ASH members.
