Q&A: ICD-10-CM coding for controlled puerperium diabetes

Q: A patient is in the postpartum period after delivering a healthy baby girl. She developed diabetes mellitus during the pregnancy. She is being treated with Metformin, an oral hypoglycemic drug. How would this situation be reported in ICD-10-CM?

A: The code for this encounter is:

• O24.435, Gestational diabetes mellitus in puerperium, controlled by oral hypoglycemic drugs

Diabetes developed during the pregnancy; therefore, it is considered gestational diabetes. It cannot be preexisting diabetes because she did not have diabetes before she became pregnant.

The 2024 ICD-10-CM Alphabetic Index main term is “Diabetes,” the subterm is “gestational (in pregnancy),” then “puerperal,” followed by “oral drug controlled (antidiabetic) (hypoglycemic),” which leads coders to O24.435.

According to section I.C.15.i (Gestational [pregnancy induced] diabetes) of the 2024 ICD-10-CM guidelines, “If a patient with gestational diabetes is treated with both diet and oral hypoglycemic medications, only the code for ‘controlled by oral hypoglycemic drugs’ is required.”

Yet additional codes Z79.4, Long-term (current) use of insulin, and Z79.85, Long-term (current) use of injectable non-insulin antidiabetic drugs, to report the medication would not be assigned in this situation since codes from subcategory O24.4- already report how the condition is controlled.

Editor’s note: This Q&A was originally published in JustCoding. This question was answered by Terry Tropin, MSHAI, RHIA, CCS-P, an AHIMA-approved ICD-10-CM/PCS trainer who taught medical terminology and medical coding at Montgomery College in Maryland for more than two decades, during the HCPro webinar, “2024 ICD-10-CM/CPT Coding for Diabetes Diagnoses and Treatment.”