Status of Glucose Metabolism and the Factors Affecting It, in Children with Thalassemia Major.

Abnormalities of the glucose metabolism are well documented in patients with Thalassemia Major who are frequently transfused and receiving therapy for chelation, due to excess iron deposition in the pancreas. The incidence of abnormalities in the glucose metabolism increase with age, with peak incidence between 16–20 years. The Indian (Asian) population is genetically predisposed to developing type 2 diabetes mellitus which is an additional risk factor for our Thalassemic population. Chelation is suboptimal in most of the patients due to economic reasons and ignorance. Impaired glucose tolerance (IGT) usually precedes the development of frank diabetes mellitus and intensive chelation in those with impaired glucose tolerance test may delay/prevent the onset of diabetes mellitus. Hence it is important to know the glyco-metabolic status of these children. At our Thalassemia endocrinology clinic, glucose tolerance test (GTT) is performed routinely in all subjects with Thalassemia major who have not already developed diabetes to identify the “at risk” population.GTT is performed by drawing a baseline fasting sample for blood glucose, oral glucose was given in a dose of 1.75mg/kg upto a maximum of 75 gms. Blood glucose level is measured 2 hours after oral glucose. According to the WHO criteria, Fasting plasma glucose between 110–126mg/dl is classified as impaired fasting and above 126mg/dl as diabetes. 2-hour plasma glucose value between 140–200mg/dl is classified as impaired glucose tolerance and above 200 mg/dl as diabetes. The purpose of this study was to analyze the status of the glucose metabolism of children and young adults with Thalassemia major who were attending our Thalassemia endocrinology clinic and to compare the factors affecting subjects with an abnormal glucose metabolism with those who have a normal glucose metabolism. The parameters compared were: effect of mean S. ferritin levels, age of onset of chelation and genetic predisposition. Retrospective analysis of our case records was done to determine the prevalence of diabetes and impaired glucose tolerance in children and young adults between 13 and 25 years of age. Of the 33 subjects evaluated, 16 out of 33 (48.5%) subjects had an abnormality of the glucose metabolism. 14/33 subjects (42.4%) had developed diabetes mellitus and 2 had an impaired GTT. Of the 16 affected subjects 9 were males and 7 were females (M:F = 1.28:1). The mean serum ferritin for this group was 5464ng/ml, 5503ng/ml for the diabetic group and 5425 for those with impaired GTT. (Range 2523–10904ng/ml). History of diabetes in a first or second degree relative was positive in 9 subjects(56.25%), negative in 2 and unknown in 5 subjects. Average age of onset of chelation was 8 years in this group. Oral glucose tolerance test was normal in 17/33(51.5%) subjects of which 10 were males and 7 were females (1.42:1). Average serum ferritin was 4747.4ng/ml in the group with a normal glucose tolerance. (1600–8294ng/ml). Family history of diabetes in a first or second degree relative was positive in 8 subjects(47%), negative in 4 and unknown in 5 subjects. Average age of onset of chelation was 6.5 years in the group with normal glucose metabolism. In conclusion of the 33 subjects evaluated, 48.5% had an abnormal glucose metabolism.