When Diabetes Doesn't Fit the Box: Understanding Ketosis-Prone Diabetes

Type 1 diabetes and type 2 diabetes are the most common forms, but doctors have identified other, rarer conditions that don't fit either mold. One of these is ketosis-prone diabetes (KPD). While KPD can present with the same serious symptoms as type 1 or type 2—like very high blood sugar or diabetic ketoacidosis—its underlying biology and progression are distinct.

KPD is challenging to diagnose because it can masquerade as type 2 diabetes at first, leading to delayed recognition and incorrect treatment approaches. The condition remains under-recognized in clinical practice, meaning many patients may live with a misdiagnosis for years.

A recent case published in medical literature illustrates how tricky KPD can be to identify. A 22-year-old man came to the emergency room with high blood sugar and was initially diagnosed with type 2 diabetes. His doctors adjusted his treatment carefully, monitoring him closely over months.

What happened next was unusual: as insulin doses kept increasing—eventually reaching 56 units of basal insulin at night plus 12 units with meals—the patient's blood sugar remained difficult to control. After several months of treatment, his patterns shifted again. He began experiencing low blood sugar episodes, so his doctors gradually removed him from insulin. Remarkably, he maintained stable blood sugar without any insulin for eight months before his condition flared up again.

This roller coaster—severe insulin resistance, then sudden improvement without insulin, then relapse—is a red flag for ketosis-prone diabetes, not typical type 2 diabetes.

To distinguish KPD from type 1 or type 2 diabetes, doctors use an A-β classification system. This system looks at two key features: whether a person has diabetes-related autoantibodies in their blood, and whether their pancreas still has functional beta cells (the cells that make insulin).

In the case described, autoantibody testing showed mildly elevated levels, but doctors determined these were not high enough to indicate classic type 1 diabetes. Combined with the patient's unusual clinical course, this suggested a KPD presentation known as the A-β+ phenotype—meaning some autoantibodies are present alongside retained beta-cell function.

Continuous glucose monitoring played an important role in tracking the patient's patterns over time, revealing the shifts in insulin needs that helped point toward the real diagnosis.

Because KPD is under-recognized, patients may receive treatment designed for type 2 diabetes or type 1 diabetes when their condition actually requires a different approach. A correct diagnosis helps doctors tailor monitoring and treatment to match how the disease actually behaves in each person.

If you or a loved one has been diagnosed with diabetes but your disease course seems unusual—such as needing very high insulin doses initially, then later needing much less, or showing patterns that don't match your diagnosis—it may be worth discussing the possibility of KPD with your healthcare team. Asking for a thorough evaluation, including autoantibody testing and assessment of pancreatic function, can help ensure you get an accurate diagnosis.

Source: Cureus. Evidence type: PubMed indexed literature. Type1Cure is an information and intelligence hub, not a medical advice service. This article summarizes published research and does not provide diagnosis, treatment, or personal medical guidance. Always talk to your own care team before changing anything about your Type 1 diabetes management.