Thursday, March 18, 2021

Insulin, Injectables, and Oral Diabetic Medication Guidelines

This installment of “In the kNOW” addresses ICD-10-CM Official Coding Guideline changes to I.C.4.a.3 and I.C.4.a.6.  Both of these guidelines discuss code assignment for diabetes and the use of medication to treat the disease.  Let’s break these guidelines down and look at each component in detail to get a better understanding.

The first clarification we find in guideline I.C.4.a.3 is if a patient uses insulin but the type of diabetes is not specified in the documentation, the default is to code the diabetes to E11- for type 2 diabetes.  This is actually in line with the guideline that immediately precedes this one, I.C.4.a.2 which states unspecified diabetes should be coded as type 2.  It is important to remember that type 2 diabetics may be treated with insulin, oral hypoglycemic medication, or simply with lifestyle changes involving diet and exercise.  Therefore, the use of insulin alone cannot drive a coder to conclude that the diabetes being treated is type 1.

The next bit of information from I.C.4.a.3 is that long-term use of medication codes should be assigned as appropriate.  That means picking up Z79.4 if the patient is on long-term use of insulin; Z79.84 if the long-term medication usage is with oral hypoglycemic drugs; and in a new addition to the guideline for 2021, Z79.899 assigned if the patient is on an injectable non-insulin antidiabetic drug.

The key to assigning the long-term medication codes is to understand the hierarchy built into the guideline:

Treatment                                                                   Code Assignment

Insulin (alone or with oral hypoglycemic med)           Z79.4 ONLY

Insulin with injectable non-insulin                               Z79.4 and Z79.899

Oral hypoglycemic med (alone)                                  Z79.84

Oral hypoglycemic med with injectable noninsulin     Z79.84 and Z79.899

Injectable non-insulin                                                  Z79.899


How is a coder to recognize the different medications?  It is important to be familiar with various types of these medications and/or use reliable resources to make the determination as a patient’s record is reviewed.  Here are some common types of each of these medications to help you get started:

Insulin                                Oral hypoglycemic              Injectable non-insulin

Novolog                             Glyburide                            Victoza

Humulin                             Metformin                           Trulicity

Levemir                              Glipizide                              Byetta


Guideline I.C.4.a.6, which addresses secondary diabetes coding, carries forward the same information regarding the use of long-term medication coding and new addition directed towards the injectable non-insulin medication code assignment.

Both guidelines mentioned here also include the caveat that type 2 diabetics may be treated with insulin short-term to manage a hyperglycemic event.  This short-term use of insulin to bring the diabetes under control does not constitute long-term treatment and the use of Z79.4 is not appropriate in that circumstance.

Now you are In the kNOW!!


About the Author 

Dianna Foley, RHIA, CHPS, CCS  is OHIMA's Coding Education Coordinator. Dianna has been an HIM professional for 20 years. She progressed through the ranks of coder, department supervisor, and department director, to her current role as a coding consultant. 

She recently served as the program director for Medical Coding and HIT at Eastern Gateway Community College. Dianna earned her bachelor's degree from the University of Cincinnati subsequently achieving her RHIA, CHPS, and CCS certifications. She is an AHIMA Approved ICD-10-CM/PCS Trainer and a a presenter at regional HIM meetings and the OHIMA Annual Meeting.