SUN-532 Mitochondrial Diabetes In Pregnancy: A Case Report

Abstract Disclosure: L. Hamann: None. A forty year old patient with T2DM presented to our clinic for diabetes management during pregnancy. Her DM had developed in her thirties with metformin failure; at the time of presentation she was utilizing SGLT2i and GLP1 therapies. Given pregnancy, she was initiated on an algorithm-driven insulin pump by our team and was seen for monthly follow-up. We reviewed the indication for retinal evaluation each trimester and the patient commented that she followed with a retina specialist for retinal dysplasia. This prompted a conversation about her diabetes history. The patient shared her DM had been suboptimally-controlled, even on insulin, and that she had multiple family members with DM. Further conversation revealed a family history of renal disease and hearing loss along her maternal line. The possibility of atypical diabetes was raised due to late-onset of insulin-requiring diabetes and the comorbidities of retinal dysplasia, recurrent pregnancy loss, lactic acidosis, exercise intolerance, fibromyalgia, hypertriglyceridemia, and adrenal incidentaloma. This patient had negative diabetes autoantibodies and measurable c-peptide. We evaluated her details using the Exeter monogenic diabetes calculator. Genetic testing confirmed a diagnosis of MIDD/MELAS with m.3243A>G mutation in MTTL1 gene. We reached out to specialty sites for the management of rare diabetes subtypes and mitochondrial disease specialists. There are limited case reports for mitochondrial disease in pregnancy and only six that focus on MIDD/MELAS. We connected our patient with cardiology and nephrology services at our site as well as a mitochondrial disease center. She continued with maternal fetal medicine, ophthalmology, and endocrinology. She was found to have cardiomyopathy; her screening was negative for arrhythmias and nephropathy. A primary c-section was planned given her newly-diagnosed structural heart disease. The patient was managed on pump therapy for the remainder of her pregnancy. Her insulin resistance increased significantly and at the time of delivery she was requiring more than 200 units of insulin daily and had an insulin to carb ratio of 1:1 A growth scan at 34 weeks demonstrated severe intrauterine fetal growth restriction with male fetus measuring <5%ile. Pearls to remember when treating diabetes associated with mitochondrial disease include the strict avoidance of metformin, the potential addition of pioglitazone to assist with glucose uptake in the skeletal muscle, the need to monitor for lactic acidosis during physically stressful periods, and prompt treatment of stroke-like symptoms with L-arginine. It is also important to use a genetic testing organization that can perform testing on mitochondrial DNA; most genetics labs can check for monogenic diabetes by germline panel and will not identify mitochondrial variants. Presentation: Sunday, July 13, 2025