Hello Dr Chalam, I am a Diabetologist working in Bangalore India, From my experience these prepubertal patients with thalassemia major with secondary diabetes tend to have high levels of insulin resistance due to deposition of iron in the liver and other organs apart from the resistance due to hormonal changes. Due to this their daily requirements of insulin goes very high in relation to weight. You may need to switch to basal bolus regimen for him is what I feel. We have tried small doses of Metformin in some of these patients and had improvement in control. Although there is not much evidence on such use of Metformin. Ofourse consider iron chelation and discussion with the hematology team. Hope this helps. All the best.