A 41-year-old woman presents to her primary care provider complaining of fatigue and an unintentional 7-lb weight loss occurring over 2 weeks. The patient denies recent travel, changes in her diet, or the addition of any new supplements or over-the-counter medications. She reports increased thirst and hunger but no fever, chills, or night sweats. She has experienced no changes in her bowel or bladder habits, nor has she had any nausea, vomiting, or abdominal pain. She also reports no palpitations or tachycardia, and no psychological symptoms, such as depression or anxiety.
The patient has a history of autoimmune thyroid disease (Hashimoto thyroiditis) and seasonal allergies. She reports recent uveitis of her right eye that resolved with treatment. She has no surgical history. Her medications include levothyroxine 112 mcg/d and loratadine 10 mg as needed. She is up to date with recommended health maintenance and annual wellness checks. Her family history is significant for Graves disease in her maternal grandfather and Hashimoto thyroiditis in her mother and 2 maternal aunts. She has no family history of diabetes, cardiovascular disease, or cancer.
Physical examination reveals a healthy woman in no apparent distress, with moist mucous membranes, no palpable thyroid mass or nodule, a regular heart rate and rhythm, and clear lung sounds. Her abdomen is soft and nontender, with positive bowel sounds in all quadrants. Laboratory tests indicate the patient is biochemically euthyroid, with unremarkable complete blood cell count and comprehensive metabolic panel except for increased nonfasting glucose level at 324 mg/dL and increased glycated hemoglobin (HbA1c) at 12.1% (Table 1).
The patient is diagnosed with type 2 diabetes (T2D) and started on metformin 500 mg twice a day, with the dosage increase to 1000 mg twice a day after 1 week, and insulin glargine 20 units every evening, titrating up by 2 units every other night to a goal fasting blood sugar level between 80 and 130 mg/dL. She is advised about lifestyle modifications including a healthy diet and exercise regimen, provided with a glucometer and logbook, and asked to check her fasting blood glucose level daily.
She returns to the clinic 4 weeks later on her current dose of insulin glargine (22 units) and reports documenting fasting blood glucose levels between 70 to 150 mg/dL. She notes that she gained 3 lb and her fatigue, appetite, and thirst decreased. The patient reports that she does not feel comfortable with her diagnosis and requests referral to an endocrinologist.
The patient undergoes evaluation by an endocrinologist, who orders a pancreatic islet cell autoantibody panel and C-peptide level. Test results are reported as positive for glutamic acid decarboxylase autoantibody (GAD65) at a level of 0.06 nmol/L (normal is <0.02 nmol/L), and the patient is determined to have a low-normal fasting C-peptide level of 1.0 ng/mL (range, 0.8-3.6 ng/mL). Based on these results, she is diagnosed with latent autoimmune diabetes in adults (LADA), a form of type 1 diabetes (T1D).
Metformin is discontinued, and she is started on a glucagon-like peptide-1 (GLP-1) receptor agonist and continued on insulin glargine 18 units nightly. Three months after the patient’s initial diagnosis, her HbA1c level decreased to 5.8%. Due to some preserved β-cell function, she is able to use only basal insulin and the GLP-1 receptor agonist for the next 8 months, at which time she is switched to intensive basal-bolus therapy via an insulin pump when her HbA1c increases to 7.8%.
With this regimen, she has kept her HbA1c in the 6.5% to 7.8 % range for the past 3 years and does not have any diabetes complications.