THU363 Misdiagnosing Latent Autoimmune Diabetes Mellitus In Adults: A Case Report

Abstract

Abstract Disclosure: U. Rafat: None. W. Akhter: None. R. Alshantti: None. J.L. Gilden: None. Background: Latent Autoimmune Diabetes Mellitus (DM) in Adults (LADA) is often misdiagnosed as Type 2 DM. This can lead to increased risk of complications. Therefore, knowledge and awareness of LADA is essential. LADA is diagnosed based on three features, age greater than 35 years, presence of antibodies to pancreatic islet cell antigens (Glutamic Acid Decarboxylase GAD, Insulinoma antigen-2 IA-2A, Zinc Transporter 8 ZnT8A) and lack of insulin requirement for at least 6 months after diagnosis. It is important to diagnose LADA early, so that patients can be started on insulin earlier, thereby achieving better glycemic control and preserving residual beta cell function. Case Presentation: We present the case of a 44-year-old female of mixed African American and Greek ethnicity with a history of DM complicated by nephropathy, hypertension, obesity, acne and uterine fibroids. She was diagnosed with Type 2 DM at age 36 from routine screening with a HbA1c of 6.9% and started on Metformin by primary care provider. Family history was significant for transient postpartum hypothyroidism in her mother, and DM in both maternal and paternal grandparents. She was unable to tolerate Metformin due to gastrointestinal side effects and was switched to Insulin Detemir therapy one year later. She first presented to the endocrine clinic for evaluation and management of abnormal thyroid function tests with symptoms of weight loss, excessive hair fall, anxiety, and palpitations. Vital signs: Blood pressure 146/65 mmHg, Heart rate 89 bpm, Respiration 14 breaths/min, BMI 31 kg/m2. Physical examination was significant for marked edema of eyelids, but no thyromegaly or tremors, and marked acanthosis nigricans. Laboratory tests were consistent with Grave’s disease with TSH less than 0.005 uIU/mL (n= 0.358-3.74), free T3 22.93 pg/mL (n=2.18-3.98), free T4 4.63 ng/dL (n=0.76-1.46) and positive TSI of 291%. (n<140). The patient was started with methimazole therapy. GAD 65 was found to be positive >250 IU/mL (n<5) and islet cell antibodies were negative. A revised diagnosis of LADA was made. The co-existence of Grave’s disease enabled reclassifying the type of her DM. Conclusion: Type 1 diabetes mellitus or autoimmune diabetes mellitus should always be ruled out if the clinical picture does not match with type 2 Diabetes Mellitus or in a relatively young patient. Our case aims to increase awareness of Autoimmune Polyendocrine syndrome, which occurs as a result of loss of immune tolerance, leading to impairment of multiple endocrine glands.