Glucose Homeostasis Markers in Beta-Thalassemia.

Background: Glycosylated hemoglobin (HbA1c) has been a well-recognized marker of glucose homeostasis among thalassemics. Recently some studies have proposed the role of fructosamine as a better marker as compared with HbA1c. Hence, the study was carried out to find out which marker holds promise among Indian beta-thalassemic children.
Methods: In this case-control study, 60 diagnosed cases of beta-thalassemia major and equal number of normal controls who were ≥8 years of age were enrolled. HbA1c, fructosamine, and fasting insulin levels were measured in all. Oral glucose tolerance test was done as a gold standard and the measured parameters were compared.
Results: HbA1c was significantly higher in cases (7.10% [±0.47%]) than in controls (5.15% [±0.19%]) (P<0.001). Thalassemics with abnormal glucose tolerance had higher HbA1c level (7.34% [±0.57%]) than those with normal glucose tolerance (7.05% [±0.43%]) (P=0.05). Insulin resistance was noticed among thalassemics with abnormal glucose tolerance as compared with their normal counterparts (P=0.04). No significant difference was found in fructosamine levels between cases (239.80 [±31.80] μmol/L) and controls (234.10 [±21.34] μmol/L) (P=0.25) or between thalassemics with abnormal glucose tolerance (243.92 [±21.94] μmol/L) and their normal counterparts (238.77 [±33.93] μmol/L) (P=0.62).
Conclusions: The use of HbA1c as a diagnostic marker for diabetes in hemolytic anemias has to be done with caution as its baseline values are higher in them. Despite this finding, HbA1c continues to be a good marker for worsening glucose homeostasis in thalassemics as higher values were found in thalassemics with abnormal glucose tolerance compared with their normal counterparts. The present study did not find any relationship of fructosamine levels with impaired glucose tolerance in beta-thalassemia.