Abnormal glucose tolerance in beta-thalassemia: assessment of risk factors.

In beta-thalassemia (beta-thal) major, the pathogenetic mechanisms leading from siderosis to diabetes are poorly understood. We assessed the glycometabolic status in transfusion-dependent Egyptian beta-thal patients and evaluated their possible risk factors for abnormal glucose tolerance (AGT). An oral glucose tolerance test (OGTT) was done on 54 multi-transfused patients and 28 age-matched normal controls, measuring their serum insulin levels at 0 and 120 min. Insulin sensitivity and insulin release indices were calculated. Indicators of iron overload and liver status were recorded. Thirteen patients (24.1%) had AGT. Cases with AGT had significantly higher mean postprandial insulin, fasting insulin resistance index (FIRI) and homeostasis model assessment (HOMA) insulin resistance (IR), p = 0.0001 for all, and significantly lower mean HOMA beta cell, p = 0.007, when compared with normal glucose tolerance (NGT) cases. Abnormal glucose tolerance is common in multi-transfused beta-thal major patients and could be attributed to early impaired beta-cell function with increasing IR.