Reader Question: Assign Type I for Patients With Type 1.5 Diabetes

Question: I just read your June 2004 article "New Edition of ICD-9 Gives Your Diabetes Codes a New Look" and was disappointed to see that type 1.5 diabetes, or latent autoimmune diabetes of adulthood (LADA), still does not have a separate code. This is a "milder form" of type I diabetes with incomplete autoimmune beta-cell destruction. There is no component of insulin resistance. To code a patient as type I, many clinicians and coders mistakenly assume that the patient must be taking insulin -- and type 1.5 diabetics often do not. This often leads me to assign type II to patients with type 1.5 because their treatment includes an oral agent. What is the most accurate code to use when a patient has a diagnosis of type 1.5 diabetes? Do you think there will eventually be a separate ICD-9 code for this diagnosis?

New Mexico Subscriber

Answer: You pose an excellent question, particularly because many coders and clinicians have never even heard of type 1.5 diabetes. The medical community considers this condition to be a latent autoimmune disorder, and physicians frequently refer to type 1.5 diabetes as a slow-acting type I diabetic condition. Experts therefore suggest that you assign type I diabetes, not type II, to a patient with type 1.5 diabetes. This means you should select from the fifth digits "1" and "3" in the 250.xx series (Diabetes mellitus). Code 250.x1 would indicate a type I diabetic not stated as uncontrolled, and 250.x3 would indicate an uncontrolled type I diabetic.

Experts recommend assigning type I diabetes for a type 1.5 diabetic patient because type 1.5 is really a diagnosis of latent autoimmune diabetes -- and type I diabetes is essentially an autoimmune condition. Although a separate code for type 1.5 diabetes would certainly provide greater coding clarity and specificity, it is unclear as of now whether ICD-9 will create a new code for this condition.

Forget about insulin use: And just a reminder -- you can stop worrying about insulin use when you assign a patient's diabetes type. The new ICD-9 changes, which will be effective Oct. 1, 2004, include descriptor changes for type I and type II diabetes. You will no longer see "insulin dependent" and "non-insulin dependent" designations because these terms lead many physicians and coders to incorrectly assign type I diabetes when patients use insulin. ICD-9 also deleted the "adult-onset type" designation from the type II descriptor to eliminate confusion. Patients of all ages can develop type II diabetes, and the term "adult-onset" misled coders.