Certified Diabetes Care and Education Specialist (CDCES) Practice Exam

A new patient, unsure of her diabetes type, presents with a low normal C-peptide and positive GAD and islet antibodies. What type of diabetes does she likely have?

1. Type 2 diabetes mellitus

2. Type 1 diabetes mellitus

3. Latent autoimmune diabetes in adults (LADA)

4. Maturity onset diabetes of the young

The correct answer is: Latent autoimmune diabetes in adults (LADA)

The presence of low normal C-peptide levels alongside positive GAD (glutamic acid decarboxylase) and islet antibodies strongly suggests that the patient likely has Latent Autoimmune Diabetes in Adults (LADA). LADA is characterized by an autoimmune process similar to that in type 1 diabetes, which leads to the destruction of insulin-producing beta cells, but it typically presents later in life, often resembling type 2 diabetes initially. The low normal C-peptide indicates that the pancreas is producing some insulin, but not enough to meet the body’s needs, distinguishing it from type 1 diabetes where C-peptide levels are usually very low or undetectable due to significant beta-cell destruction. The presence of autoantibodies (such as GAD antibodies) is a hallmark of autoimmune diabetes. These antibodies indicate the patient's immune system is attacking the beta cells, which is consistent with LADA. In contrast, type 2 diabetes is often associated with insulin resistance and usually presents with higher C-peptide levels, reflecting increased insulin production due to insulin resistance. The distinction from maturity onset diabetes of the young (MODY) is important as MODY typically presents with a family history of diabetes, a different genetic basis, and