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ICD-10-CM 2027 diagnosis code

O24.012Pre-existing type 1 diabetes mellitus, in pregnancy, second trimester

✓ Billable / specificCC — complication/comorbidityMaternity · age 9–64Female only

O24.012 is a valid, billable ICD-10-CM code for pre-existing type 1 diabetes mellitus, in pregnancy, second trimester. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.Short description: Pre-existing type 1 diabetes, in pregnancy, second trimester

Code last changed in FY2017 (effective October 1, 2016). Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About O24.012

O24.012 is the ICD-10-CM diagnosis code for pre-existing type 1 diabetes mellitus, in pregnancy, second 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 O24.01 (pre-existing type 1 diabetes mellitus, in pregnancy), O24.012 is specifically for pre-existing type 1 diabetes mellitus, in pregnancy, second trimester. Related codes cover first trimester (O24.011), third trimester (O24.013) and unspecified trimester (O24.019).

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 changed in FY2017 (title revised).

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).

Notes that apply from higher levels

Instructions written at a parent level also apply to O24.012.

› From O24.0 Pre-existing type 1 diabetes mellitus, in pregnancy, childbirth and the puerperium
Use additional code
  • code from category E10 to further identify any manifestations

Broader instructions also apply from O20-O29 Other maternal disorders predominantly related to pregnancy and Chapter 15: Pregnancy, childbirth and the puerperium.

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 648.01Diabetes mellitus of mother, complicating pregnancy, childbirth, or the puerperium, delivered, with or without mention of antepartum conditionapproximate
  • 648.03Diabetes mellitus of mother, complicating pregnancy, childbirth, or the puerperium, antepartum condition or complicationapproximate

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • FY2017 (effective 10/1/2016): Title revised — was “Pre-existing diabetes mellitus, type 1, in pregnancy, second trimester”

Common questions about O24.012

Is O24.012 billable?

Yes. O24.012 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can O24.012 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict O24.012 as a principal diagnosis.

Is O24.012 a CC or MCC?

O24.012 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does O24.012 group to?

O24.012 is used in the MS-DRG v44.0 logic for MS-DRG 817 (Other Antepartum Diagnoses with O.R. Procedures with MCC), MS-DRG 818 (Other Antepartum Diagnoses with O.R. Procedures with CC), MS-DRG 819 (Other Antepartum Diagnoses with O.R. Procedures without CC/MCC), MS-DRG 831 (Other Antepartum Diagnoses without O.R. Procedures with MCC), MS-DRG 832 (Other Antepartum Diagnoses without O.R. Procedures with CC) and MS-DRG 833 (Other Antepartum Diagnoses without O.R. Procedures without CC/MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for O24.012?

The CMS General Equivalence Mappings map O24.012 to ICD-9-CM 648.01 and 648.03.