Survivors of childhood leukaemia treated with haematopoietic stem cell transplantation and total body irradiation should undergo screening for diabetes by oral glucose tolerance tests.

Aims: Childhood cancer survivors treated with haematopoietic stem cell transplantation (HSCT) and total body irradiation are at an increased risk of developing diabetes early in life due to insulin resistance and β-cell dysfunction, but the optimal screening method is unknown. The National Institute for Health and Care Excellence guidelines for community diabetes screening recommend using fasting glucose ≥ 7 mmol/l and/or HbA1c ≥ 48 mmol/mol (6.5%) for diagnosis and, fasting glucose 5.5-6.9 mmol/l or HbA1c 42-47 mmol/mol (6-6.5%) to indicate high risk. This study aimed to evaluate the sensitivities of fasting glucose and HbA1c in the diagnosis of diabetes and impaired glucose tolerance in childhood HSCT survivors.
Method: The patients were 35 (male = 19) HSCT survivors from a single UK centre under follow-up from 2006 to 2013. Patients had a median age (range) of 19.2 (13.1-26.2) years and had been treated for acute lymphoblastic (n = 31) or myeloid (n = 4) leukaemia when aged 7.8 (2.4-16.7) years. The outcome measures were oral glucose tolerance test (OGTT), fasting glucose and HbA1c .
Results: OGTT identified 6 patients with diabetes (120-min glucose ≥ 11.1 mmol/l), 12 with impaired glucose tolerance (120-min glucose 7.8-11.0 mmol/l) and 2 with impaired fasting glucose (≥ 7 mmol/l). Fasting glucose ≥ 7 mmol/l or HbA1c ≥ 48 mmol/mol identified two of the six patients with diabetes diagnosed on OGTT. Fasting glucose ≥ 5.5 mmol/l and HbA1c ≥ 42 mmol/mol identified three and two patients, respectively, with diabetes. Only 1 of 12 patients with impaired glucose tolerance had a fasting glucose ≥ 5.5 mmol/l and none had HbA1c ≥ 42 mmol/mol (≥ 6%).
Conclusions: The fasting glucose and HbA1c cut-offs used in UK population screening only identified one-third of HSCT survivors with diabetes and do not identify those at risk. Diabetes screening in HSCT survivors requires standard OGTTs.
(© 2016 Diabetes UK.)