ICD 10 Coding Alert

Question: The provider documents type 2 diabetes with hyperglycemia managed with metformin, basal insulin, and a weekly injectable GLP-1 receptor agonist. When should I report Z79.4, Z79.84, or Z79.85 with a diabetes diagnosis? If a patient uses more than one type of diabetes medication, may I report multiple Z79.- codes?

South Carolina Subscriber

Answer: According to the FY 2026 ICD-10-CM Official Guidelines for Coding and Reporting, you should assign the appropriate additional code from category Z79.- (Long term (current) drug therapy) when the record shows that a patient with diabetes routinely uses insulin, an oral hypoglycemic drug, or an injectable noninsulin antidiabetic drug as ongoing therapy. Remember, too, that the way the patient takes the medication matters for code selection.

Here’s a look at when you should report these codes:

• Report Z79.4 (Long term (current) use of insulin) for insulin and Z79.84 (Long term (current) use of oral hypoglycemic drugs) for oral agents.
• Report Z79.85 (Long-term (current) use of injectable non-insulin antidiabetic drugs) when the patient uses an injectable glucagon-like peptide-1 (GLP-1) receptor agonist or another injectable noninsulin antidiabetic drug to treat diabetes.

An oral GLP-1 receptor agonist used for diabetes supports Z79.84, not Z79.85. Do not assign Z79.85 solely because a GLP-1 drug is prescribed for obesity or another nondiabetes indication; link the medication-use code to the condition being treated based on the documentation. If the patient routinely uses medications from more than one class, assign the respective Z79.- code for each class.

Do not assign Z79.4 when insulin is administered only temporarily to bring a patient with type 2 or secondary diabetes under control during an encounter. Also, do not add Z79.4 routinely to an E10.- (Type 1 diabetes mellitus) code because type 1 diabetes inherently requires insulin use. For gestational diabetes, do not assign Z79.4, Z79.84, or Z79.85 with a code from subcategory O24.4 (Gestational diabetes mellitus); the gestational diabetes code itself identifies the method of control.

So, for this situation, you’ll report the appropriate E11.- (Type 2 diabetes mellitus) code for the diabetes and documented complication, plus Z79.4, Z79.84, and Z79.85 to identify all three forms of long-term therapy.

Rachel Dorrell, MA, MS, CPC-A, CPPM, Production Editor, AAPC