Case: A South Indian boy diagnosed with ataxic telangectaisa(AT) since aged 5 years (homozygous mutations for ATM gene at C1966A>C and 1968-X.delI), presented with type 2 diabetes (T2DM) aged 15.9 years. There was a 4-week history of polyuria and polydipsia without weight loss. Investigations showed fasting glucose 11.5 mmol/l, insulin 209 pmol/l, HbA1c 103 mmol/mol, negative glutamic acid decarboxylase and islet cell antibodies, and urinary C-peptide 2.84 nmol/mol. Intellectually he is normal and attends mainstream school with physical assistance. His father and five paternal siblings were diagnosed with T2DM aged <50 years. On examination, he was Tanner stage 5 and non-obese (BMI 23.2 kg/m2, SDS 1.15). There were no signs of acanthosis nigricans. Telangiectasia were present on his sclerae and he was ataxic with limited mobility with a mild scoliosis. Metformin 500 mg once daily was started and he responded well with fasting glucose maintained between 5 and 6 mmol/l most days and achieved an HbA1c of 47 mmol/mol 1 year after diagnosis. Screening for coeliac disease, thyroid dysfunction, diabetic nephropathy and retinopathy were negative. However, mildly raised total cholesterol 5.3 mmol/l and triglyceride 2.7 mmol/l, and low HDL 0.9 mmol/l were noted. He also has raised transaminase (ALT 209 U/l) and ultrasound findings of hepatic steatosis.
Discussion: T2DM is a rare complication in patients with AT which usually presents in adulthood. It is characterised by hyperinsulinism, negative antibodies and liver dysfunction, without clinical obesity and responds well to metformin. It has been proposed that mutations of the ATM gene in AT leads to disruption of the downstream signalling pathways in the insulin-stimulated glucose transport at the skeletal muscles, and hence glucose clearance. Our case demonstrates that diabetes and metabolic complications in AT can present in the paediatric age range, and screening should be part of the follow-up of AT from childhood.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology