Endocrine Abstracts

JOINT2868

Background: The iron overload occurring in patients with transfusion-dependent B-thalassemia causes a wide range of endocrine disorders, one of the most common being glucose dysregulation. Both insulin deficiency and resistance are reported in these patients. Current recommendations require assessment of glucose abnormalities by testing fasting blood glucose (BG) and performing oral glucose tolerance tests (oGTT) annually after a certain age. A new promising method for determining glucose disorders is the use of continuous glucose monitoring system (CGM).

Case reports: We present three cases of patients with transfusion-dependent B-thalassemia (TDT) with high ferritin levels (above 1000 ng/mL despite of the chelating therapy) and glucose dysregulation. Fasting blood glucose and extended oGTT were conducted to evaluate the glucose homeostasis along with the calculation of HOMA-IR. CGM (Dexcome One) was applied to each of them for a period of one week. MRI was conducted to evaluate the iron overload in the liver and pancreas. The first patient (14 years, male) had normal HOMA-Ir = 0. 88, but oGTT showed pronounced hyperinsulinism and impaired glucose tolerance – BG at 120’- 9. 2 mmol/l. CGM data showed postprandial glucose elevation up to 15. 3 mmol/l and mean BG 6. 2 mmol/l. The second patient (14 years, female) had insulin resistance according to HOMA-Ir = 3. 16, and normal BG and insulin levels during oGTT but the CGM showed postprandial BG up to 12. 5 mmol/l and mean blood glucose 8. 01 mmol/l. The third patient (8 years, female) had normal HOMA-Ir = 0. 7 and insulin levels during oGTT, no hyperglycemia. Three symptomatic episodes of hypoglycemia were observed with BG 3. 1, 2. 5 and 2. 0 mmol/l – two of them during the oGTT and one later the same day. CGM data showed postprandial glucose elevation up to 13 mmol/l, mean BG 6. 1 mmol/l.

Conclusions: The use of CGM seems to be more useful for diagnosing glucose dysregulation in patients with TDT than fasting BG and oGTT alone. More investigations and a longer follow up are needed.