DIABETES-MELLITUS IN CHILDREN SUFFERING FROM BETA-THALASSEMIA

Insulin-dependent diabetes mellitus (IDDM) is a frequent complication in patients with beta-thalassaemia major. It is believed to be a conse quence of the damage inflicted by iron overload to the pancreatic beta -cell. Liver disorders and genetic influences seem to be additional pr edisposing factors to diabetes mellitus in patients with beta-thalassa emia. Ethnic variations are frequently reported on prevalence and comp lications of diabetes mellitus in the beta-thalassaemia patients. We i nvestigated 50 Saudi children (<15 years) with beta-thalassaemia major and 50 beta-thalassaemia minor, and age- and sex-matched controls for the prevalence of diabetes mellitus, and its relation to hitherto cla imed predisposing factors. Easting blood glucose, plasma insulin level , liver function tests, plasma ferritin, iron, and transferrin were as sessed in each patient and glucose tolerance was evaluated. Results in patients with beta-thalassaemia major were compared with those obtain ed for beta-thalassaemia minor and the controls. The results showed mo derate elevation of ferritin level in the majority of the beta-thalass aemia major despite desferroxamine therapy. Either hyperinsulinaemia o r hypoinsulinaemia was encountered in the majority of these patients. The prevalence of diabetes mellitus was 6 per cent compared to 2 per c ent in the beta-thalassaemia minor and normal children. Impaired gluco se tolerance (IGT) occurred at a significantly higher (24 per cent) fr equency in the beta-thalassaemia major compared to 2 and 0 per cent in the beta-thalassaemia minor patients and normal controls, respectivel y. The prevalence of diabetes mellitus was significantly lower in the Saudi thalassaemic patients compared to the results obtained from pati ents of other ethnic groups reported in literature. Liver function abn ormalities were more frequent in this group than in the beta-thalassae mia minor and the controls. It appears from the inference of our resul ts that combinations of factors including iron overload and liver dama ge, predispose the beta-thalassaemia major patients to beta-cell damag e and, hence, to impaired glucose tolerance.