Against the Grain: Insulinoma-Associated Protein 2 Positive Latent Autoimmune Diabetes in Adults Defying Ethnic...

Latent autoimmune diabetes in adults (LADA) combines features of type 1 and type 2 diabetes, characterized by autoantibodies and progression to insulin dependence. Glutamic acid decarboxylase antibody is more prevalent in White populations and also prevalent to a lesser degree in Asian populations, while insulinoma-associated protein 2 (IA-2) antibodies are much less frequent in Asian populations. The objective of this report is to emphasize diagnostic reconsideration in cases of diabetes that present with atypical phenotypic or ethnic features, highlighting the value of comprehensive autoantibody testing.

A 56-year-old Japanese-American male with a history of diabetes mellitus, deep vein thrombosis, hypokalemia, and hypophosphatemia presented with hyperglycemia and fatigue. Laboratory evaluation revealed glucose 262 mg/dL (reference 70-99), glycated hemoglobin 11.6% (reference <5.7%), arterial pH 7.07 (reference 7.35-7.45), bicarbonate 2.7 mmol/L (reference 22-28), potassium 2.7 mmol/L (reference 3.5-5.0), and phosphate 0.8 mg/dL (reference 2.5-4.5). Autoimmune testing revealed IA-2 antibody positivity. He was treated with standard diabetic ketoacidosis protocol, transitioned to subcutaneous insulin, and discharged with diabetic education.

LADA involves gradual autoimmune-mediated beta-cell destruction. IA-2 positivity, while less common in Asian populations, is linked to more rapid beta-cell decline. Early insulin initiation is essential. This case emphasizes the importance of considering ethnicity gender, age, and body mass index in diagnostic evaluations.

This case highlights the importance of distinguishing LADA from type 2 diabetes in patients with atypical clinical features and emphasizes how antibody status and factors such as age, sex, and body mass index can influence diagnostic accuracy.