MON-640 Maturity Onset Diabetes of the Young Type 5 Diagnosed Following Motor Vehicle Accident

Abstract Disclosure: H. Abdalla: None. A.M. Elobeid: None. P. Takalloo: None. A. Zenebe: None. G.L. Nunlee-Bland: None. W. Odonkor: None. V. Ganta: None. N. Amadife: None. F. Adeleye: None. Background: Maturity-Onset Diabetes of the Young Type 5 (Mody-5) is a rare form of monogenic diabetes caused by mutations in the hepatocyte nuclear factor 1 beta (HNF1B) gene. In addition to diabetes, patients often experience other clinical manifestations. We present a case of HNF1B-MODY with significant extra-pancreatic features.Case History:A 19-year-old female presented after a motor vehicle accident. She had no known medical conditions and was not on any medications. She has had no weight loss, increased thirst or urination. Her family history included a father with diabetes, diagnosed 3 years ago at age 52, who is currently on oral medication. There was no other family history of diabetes. The patient had a normal BMI of 19 kg/m². Laboratory results showed elevated random blood glucose levels of 160 and 200 mg/dL, an elevated creatinine level of 1.29 mg/dL, and a low estimated glomerular filtration rate (eGFR) of 60 mL/min. Her Hb A1C was 7.6%, and 7.8% on repeat testing -diagnosing diabetes mellitus. An abdominal CT scan, performed as part of the trauma workup, revealed an atrophic right kidney and bilateral renal cysts. Testing for diabetes autoantibodies was negative, and her C-peptide level was 3.2 ng/mL. After ruling out type 1 diabetes mellitus, the patient was tested for MODY-5, as the CT findings supported the possibility of this diagnosis. Genetic testing identified a heterozygous pathogenic variant in the HNF1B gene, confirming the diagnosis of MODY-5. Further tests showed hypomagnesemia (serum magnesium: 1.5 mg/dL) and hyperuricemia (uric acid: 7.4 mg/dL), both of which are commonly associated with MODY-5. Treatment options were discussed with the patient, who chose to focus on lifestyle modifications at this time. She received comprehensive diabetes and nutrition education, and her Hb A1C improved, with a current level of 6.5%—14 months post-diagnosis. She is being monitored closely in conjunction with nephrology. Additionally, she is being treated with magnesium supplements for hypomagnesemia and allopurinol for hyperuricemia. Conclusion: This case highlights the importance of considering HNF1B mutations in patients with diabetes and kidney cysts, as well as the need to assess uric acid and magnesium levels once the diagnosis is made. While insulin therapy is often necessary, this patient showed improvement with a management plan focused on lifestyle modifications. Presentation: Monday, July 14, 2025