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Insulin resistance and beta cell function in chronically transfused patients of thalassemia major
Jyoti Suvarna1, Hemraj Ingle, C T Deshmukh
1Department of Pediatrics, Seth G.S. Medical College and K.E.M. Hospital, Parel, Mumbai 400 012, India. saumya4@vsnl.com
Insights
Chronically transfused beta-thalassemia major patients exhibit early insulin resistance, compensated by increased insulin secretion, even without diabetes. This metabolic dysfunction correlates with iron overload indicators and treatment factors.
Area of Science:
- Endocrinology
- Hematology
- Metabolic Disorders
Background:
- Beta-thalassemia major requires regular blood transfusions, leading to iron overload.
- Iron overload can affect various organs, including the pancreas, potentially impacting glycometabolic function.
- Understanding metabolic changes in these patients is crucial for early intervention.
Purpose of the Study:
- To evaluate glucose tolerance, insulin secretion, insulin resistance, and beta-cell function in children with beta-thalassemia major.
- To investigate the relationship between glycometabolic parameters and clinical/biochemical markers of iron overload.
Main Methods:
- A glucose tolerance test and assessment of fasting plasma insulin, insulin resistance index, and beta-cell function index were performed.
- 30 children with beta-thalassemia major and 10 healthy controls (ages 8-15) were studied.
- Clinical data including liver enzymes, organ size, and iron overload indicators were recorded.
Main Results:
- No cases of diabetes mellitus or impaired glucose tolerance were observed.
- Patients showed significantly higher fasting insulin levels and insulin resistance compared to controls.
- Insulin resistance correlated with age, blood transfusion volume, serum ferritin, spleen size, and chelation therapy status.
Conclusions:
- Early insulin resistance, compensated by hyperinsulinemia, occurs in chronically transfused beta-thalassemia major patients before overt diabetes.
- Metabolic dysfunction is linked to iron overload markers and treatment adherence.
- Monitoring glycometabolic function is essential in managing beta-thalassemia major.
Objective:
To assess the glycometabolic function in chronically transfused patients of beta- thalassemia major in terms of glucose tolerance, insulin secretion, insulin resistance index, and beta cell function index and to determine their relationship with clinical and biochemical profile.
Methods:
30 homozygous thalassemia major children (aged 8-15 years) receiving regular blood transfusion and 10 age and sex matched normal children attending a tertiary level hospital were subjected to glucose tolerance test, estimation of fasting plasma insulin level, insulin resistance index and beta cell function index. Liver enzymes, liver size and indicators of iron overload (serum ferritin, total units of blood transfused, splenic size) were recorded.
Results:
There was no diabetes mellitus or impaired glucose tolerance test in either the cases or the controls. Fasting plasma insulin levels were significantly higher in cases than controls (P = 0.004), and correlated well with indicators of iron overload like total units of blood transfused (r = 0.41, P = 0.03), serum ferritin (r = 0.38, P = 0.038) and splenic size (r = 0.43, P = 0.03). Insulin resistance was higher in cases compared to controls (P = 0.01). It correlated well with age (r = 0.56, P = 0.006), fasting blood glucose (r = 0.8, P = 0.003), fasting plasma insulin (r = 0.95, P = 0.00001), total units of blood transfused (r = 0.52, P = 0.005), serum ferritin (r = 0.4, P = 0.02) and splenomegaly (r = 0.51, P = 0.004). Insulin resistance was higher in patients not on chelation therapy compared with those on chelation therapy (P = 0.003). The beta cell function index was higher in cases compared to the controls, but not of statistic significance (P = 0.077). It did not correlate well with total amount of blood transfused (r = -0.32, P = 0.08), serum ferritin (r = -0.138, P = 0.46), spleen size (r = 0.16, P = 0.36), or chelation therapy (P = 0.98).
Conclusion:
Diabetes mellitus or impaired glucose was not seen in chronically transfused patients of thalassemia major (between 8 and 15 years of age), in our study. Insulin resistance, compensated by hyperinsulinemia, sets in early even before the onset of frank diabetes mellitus and correlated well with age, chelation therapy and indicators of iron overload like total units of blood transfused, splenomegaly and serum ferritin.
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