When a patient uses insulin but the type of diabetes is not documented, what code should be assigned?

The assignment of code E11.- for a patient who uses insulin but does not have the type of diabetes documented is appropriate because E11 refers to Type 2 diabetes mellitus. According to ICD-10-CM coding guidelines, when the specific type of diabetes is not specified but the patient is on insulin, it is safer to assume they have Type 2 diabetes.

Type 1 diabetes (coded E10) is typically associated with a complete lack of insulin production, while Type 2 diabetes may require insulin due to progression or other factors. Selecting E11 acknowledges that while the specific type is not clear, the patient’s need for insulin indicates a more advanced state of diabetes that aligns with Type 2.

Therefore, coding E11.- is the most accurate choice in this scenario, considering the lack of documentation regarding the exact type of diabetes while also recognizing the patient's treatment regimen.