Endocrine Abstracts

Background: Obesity is common in young people with Duchenne Muscular Dystrophy (DMD) and may lead to abnormalities of glucose homeostasis and insulin resistance. Annual measurement of HbA1c and sex hormone binding globulin (SHBG), shown to be inversely related to insulin levels, was introduced as local clinical monitoring in 2022. This report is an audit against our local guidance and service evaluation.

Methods: Based on the American Academy Paediatrics definition, HbA1c 39-46 mmol/mol was considered to be indicative of impaired glucose tolerance and HbA1c ≥47 mmol/mol was indicative of diabetes. SHBG was converted to Z scores based on published literature. Results were reported as median (range).

Results: There were 64 and 62 young people undergoing clinical review in paediatric services (neuromuscular and/or endocrine) in 2022 and 2023, respectively. Thirty-four out of 64 (53%) and 37/62 (60%) had HbA1c measured in 2022 and 2023, respectively. Thirty-seven out of 64 (58%) and 36/62 (58%) had SHBG measured in 2022 and 2023, respectively. A total of 30/64 (47%) and 36/62 (58%) had both HbA1c and SHBG measurements in 2022 and 2023, respectively. Of the 37 boys with HbA1c measured in 2023, 33/37 (89%) were <39 mmol/mol, 4/37 (11%) were 39-46 mmol/mol and none were ≥47 mmol/mol. The four boys with impaired results had a median age of 15.6 years (6.5, 18.5), each took daily glucocorticoid, three out of four were ambulant and two were white Caucasian. Two of these boys had oral glucose tolerance test confirming impaired glucose tolerance: two-hour glucose of 8.0 mmol/l (HbA1c 44 mmol/mol) and 9.6 mmol/l (HbA1c 40 mmol/mol), respectively. Median SHBG Z-scores was -0.6 (-1.5, +0.9) in the group with HbA1c 39-46 mmol/mol and was -1.1 (-2.0, +2.5) in the group with HbA1C ≤38 mmol/mol.

Conclusion: Routine HbA1c monitoring identified 11% of boys with DMD in ranges that could be indicative of impaired glucose tolerance. Overall, SHBG was low reflective of insulin resistance but was not discriminatory between those with HbA1c indicative of impaired glucose tolerance and those with normal HbA1c. National consensus guidance in this area is now needed and being developed.