Endocrine Abstracts

Background: A 29 year old female presented to the Emergency department with headache, vomiting and loose stools for 24 hours. She was not known to have diabetes. She had a background of bilateral sensorineural deafness for 6 years and resolved Gillian Barre syndrome 8 years prior. She has a family history of deafness and diabetes mellitus in her maternal grandmother and mother; and diabetes in her maternal aunty and two maternal uncles diagnosed with prediabetes. She has a partner and two children aged two and nine years with no history of diabetes or deafness.

Investigations and management: On admission her blood glucose was 22.3 mmol/l, blood ketones were raised (4.9 mmol/l), low blood low PH (6.836) and low bicarbonate (5.7 mmol/l). Other investigations were as follows: WCC 19.2, serum sodium 130 mmol/l, creatinine 68 umol/l; calcium 2.15 mmol/l, magnesium 0.50 mmol/l, HbA1c 26 mmol/mol, vitamin B12 114 ng/l, folate 7.0 mg/l, ferritin 40 mg/l and negative pregnancy test. Examination revealed low BMI (18.3) with no signs of infection on systemic examination. Patient was managed as Diabetic Ketoacidosis with fixed rate insulin infusion followed by variable rate insulin infusion. She was then assessed by the diabetic team and started on basal-bolus insulin regime; diabetes education provided on discharge. Further investigations revealed negative Anti-GAD antibodies, negative Anti-islet cell antibodies, negative TTG IGA, normal Thyroid function test. Patient is managed by Diabetes Community team and awaiting results from genetic testing for MIDD.

Discussion: Type 1 and Type 2 diabetes constitute the most common types of DM. With increasing insight into genetic medicine, monogenic diabetes has gained interest as rare aetiology of adult onset diabetes. Maternally Inherited Diabetes and Deafness is caused by mitochondrial DNA defect accounting for 1% of diabetes mellitus. A to G (adenine to guanine) substitution at 3243 is the most common associated DNA mutation which then results in defective oxidative production of energy. Salient features comprise of Diabetes, Deafness, Maculopathy and Positive family History of Deafness and Diabetes. Other features consist of left ventricular failure, focal segmental glomerular sclerosis. Approximately 20% present as type 1 DM and 8% as DKA. Diagnosis involves genetic testing of 3243 A > G mutation in blood or urine sample. Management includes early recognition and prevention of systemic complications by commencing patient on appropriate treatment and regular follow up.

Conclusion: Clinicians should have low threshold for suspecting MIDD in a patient with low BMI, Anti Gad negative and a family history of Diabetes and Deafness.