O24.420Gestational diabetes mellitus in childbirth, diet controlled

O24.420 is the ICD-10-CM diagnosis code for gestational diabetes mellitus in childbirth, diet controlled. It belongs to category O24 (diabetes mellitus in pregnancy, childbirth, and the puerperium), block O20-O29 (other maternal disorders predominantly related to pregnancy) and chapter 15 (pregnancy, childbirth and the puerperium). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within O24.42 (gestational diabetes mellitus in childbirth), O24.420 is specifically for gestational diabetes mellitus in childbirth, diet controlled. Related codes cover insulin controlled (O24.424), controlled by oral hypoglycemic drugs (O24.425) and unspecified control (O24.429).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 998 (Principal Diagnosis Invalid as Discharge Diagnosis), in MDC 14 (Pregnancy, Childbirth and the Puerperium), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

The Medicare Code Editor treats this as a maternity diagnosis, expected only for patients age 9 through 64.

It is on the CMS list of diagnoses consistent only with female patients (the sex-conflict edit itself was retired in FY2025).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 648.81 (abnormal glucose tolerance of mother, delivered, with or without mention of antepartum condition).