Endocrine Abstracts

A 47-year-old Caucasian gentleman was diagnosed with diabetes mellitus in September 2019. He presented with blood glucose 29.5 mmol/l and negative ketones in December 2020 and was treated with variable rate insulin infusion. He had short stature with height of 161 cm and weight 53.5 kg (BMI 20). There was mild weakness of quadriceps (4/5). Laboratory tests revealed high lactate (5.38 mmol/l) and HBA1c (70 mmol/mol), reduced eGFR (47 ml/min) and negative antibody. He had gradual decline in hearing required hearing aids from May 2019 and two episodes acute heart failure from 2018. Echocardiogram and cardiac MRI revealed extensive myocardial fibrosis with severely impaired left ventricular (LV) systolic function and LV thrombus requiring warfarin. He had undergone implantation of a CRT-D device in 2020 for progression of hypertrophic cardiomyopathy. He had chronic renal impairment preceding the diagnosis of diabetes with high urine PCR (235 mg/mmol) His mother had diabetes, hearing loss short stature and died of myocardial infarction. His grandmother had deafness and heart failure. His maternal two uncles had deafness and neuropathy. His sister had gestational diabetes and her child was under investigation for deafness. Genetic testing confirmed maternally inherited diabetes and deafness (MIDD) with presence of heteroplasmic m.3243A>G pathogenic mutation of MT-T11 at a level of 24%.

Discussion: Early diagnosis of MIDD is challenging when other clinical manifestations precede the diagnosis of diabetes. This case is a reminder of the importance of considering a genetic condition when diabetes is associated with additional key clinical features and a significant family history.