O24.313Unspecified pre-existing diabetes mellitus in pregnancy, third trimester

O24.313 is the ICD-10-CM diagnosis code for unspecified pre-existing diabetes mellitus in pregnancy, third trimester. 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 O24.31 (unspecified pre-existing diabetes mellitus in pregnancy), O24.313 is specifically for unspecified pre-existing diabetes mellitus in pregnancy, third trimester. Related codes cover first trimester (O24.311), second trimester (O24.312) and unspecified trimester (O24.319).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 817 (Other Antepartum Diagnoses with O.R. Procedures with MCC, relative weight 2.0534), DRG 818 (Other Antepartum Diagnoses with O.R. Procedures with CC, relative weight 1.2942), DRG 819 (Other Antepartum Diagnoses with O.R. Procedures without CC/MCC, relative weight 0.7739), DRG 831 (Other Antepartum Diagnoses without O.R. Procedures with MCC, relative weight 1.1558), DRG 832 (Other Antepartum Diagnoses without O.R. Procedures with CC, relative weight 0.7585) and DRG 833 (Other Antepartum Diagnoses without O.R. Procedures without CC/MCC, relative weight 0.5002), 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 648.01 (diabetes mellitus of mother, complicating pregnancy, childbirth, or the puerperium, delivered, with or without mention of antepartum condition) and 648.03 (diabetes mellitus of mother, complicating pregnancy, childbirth, or the puerperium, antepartum condition or complication).