Diabetes Mellitus Type 1 in Patient with Medium-Chain Acyl-Coenzyme A Dehydrogenase Deficiency

Abstract

Introduction: Medium-chain acyl-coenzyme A dehydrogenase deficiency (MCADD) is an inborn error of fatty acid oxidation requiring carbohydrate (CHO) to avoid disabling encephalopathy with non-ketotic hypoglycemia. We report diagnosis and management of T1DM in an MCADD patient. Case Presentation: Our patient was born prior to MCADD newborn screening. She did well until 2 months of age when she slept 12 hours without feeding and BG 20 mg/dl in ER required IV glucose. By 1 1/2 y/o she had 3 similar events. Pediatric endocrine identified MCADD. She avoided severe hypoglycemia by attending to CHO intake especially during illness. At 8 y/o, she noted glucosuria without ketonuria. Her test results were normal with hemoglobin A1c (HgbA1c) 5.3%. She responded well to adjusted CHO diet until 13 y/o when she noted lethargy with persistent high BG. T1DM was diagnosed with her HgbA1c 6.7%. We hypothesized long-acting glargine insulin could assist BG control without hypoglycemia. She responded well to insulin to maintain HgbA1c less than 7.5% until 15 years of age when she expressed compliance problems to present. Results: Her MCADD presented with non-ketotic hypoglycemia events, normal plasma carnitine but elevated MCADD specific octanoyl-acyl-carnitine levels. A known MCADD mutation was identified. At 13 y/o her BG 335 mg/dl, abnormal insulin release and positive pancreas islet directed antibodies were consistent with T1DM. After 1 year glargine therapy alone she required additional insulin to maintain excellent T1DM control. Discussion: MCADD requires early detection to reduce risk for tragic mortality and morbidity. Our patient requires CHO favored diet but is not obese as sometimes reported with MCADD. Management of her T1DM with MCADD requires insulin monitored to avoid hypoglycemia. T1DM is rarely or not reported in patients with MCADD. Conclusion: BG control in MCADD patients must focus on avoiding hypoglycemia but consider T1DM or other DM when an MCADD patient has persistent hyperglycemia. Disclosure G.W. Moll: None.