Intravenous glucose tolerance and plasma insulin response in children with homozygous beta-thalassaemia

The different patterns of insulin response during Oral Glucose Tolerance Test (OGTT) in transfused young patients with β-Thalassemia

BACKGROUND AND AIM

Dysregulation of glucose metabolism is a common complication of transfusions in Transfusion Dependent Thalassemia (TDT) patients. For early diagnosis of glucose disturbances, screening is recommended. The age of starting and the type of screening vary; the more common methods are assessment of RPG, FPG, 2h PG and 2 hours OGTT. The combined assessment of glucose tolerance and insulin response during OGTT is rarely recommended. The main objective of the study is the evaluation of simultaneous assessment of Glucose Tolerance (GT) and Insulin Response (IR) during OGTT in patients with TDT.

METHODS

43 TDT patients aged 12-28years, without clinical evidence of glucose disturbances, were randomly selected for the study. The 2-hour OGTT in 30 minutes intervals was applied. Plasma glucose and insulin were assessed in all samples using routine laboratory methods.

RESULTS

Of 43 patients 31(72%) had Normal GT; of them 9 (29%) had normal insulin response  (NIR), 14 (45%) high IR and 8(26%) delayed peak IR. Delayed peak IR was found in 8 of the 9 patients with Impaired GT and in 2 of the 3 with diabetic GT. Deficient IR (hypoinsulinemia) was found in two patients.

CONCLUSIONS

Simultaneous assessment of GT and IR during OGTT in TDT patients, seems to be a most sensitive and creditable screening test for early diagnosis of glucose disturbances. High IR and delayed peak IR in normoglycemic patients are valuable indices for diagnosis of the pre-diabetic state that precede the development of glucose disturbances in TDT patients and start proper follow and management.