Insulin Resistance and Iron Overload

Glucose tolerance tests performed in 15 patients (10 males and 5 females, age range 6–34 years, mean 16 years) with transfusional iron overload revealed fasting and subsequent blood glucose concentrations within the normal range in all except one patient who was overtly diabetic. However, in all patients except one, blood glucose concentration at 2 hours was higher than the respective fasting glucose concentration. All but two of the patients (one of whom was diabetic) showed fasting and post glucose hyperinsulinism. All the patients had hepatic dysfunction of varying severity. It is hence suggested that the initial disturbance of carbohydrate metabolism in transfusional siderosis is insulin resistance, similar to that found in chronic liver disease. Overt diabetes is probably a later event, occurring when sufficient damage to pancreatic cells has occurred and appropriate hyperinsulinaemia cannot be sustained.