2026 ICD-10-CM Diagnosis Code O24.019Pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester

ICD-10-CM Codes›O00-O9A›O20-O29›O24

ICD-10-CM O24.019
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

O24.019 is a billable ICD-10-CM diagnosis code for pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 817 through 819, 831 through 833. The code is restricted by the Medicare Code Editor to maternity cases (age 9 through 64). Coders also document this condition as pre-existing diabetes mellitus in pregnancy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Diabetes mellitus without complication; Diabetes mellitus, Type 1; and Diabetes or abnormal glucose tolerance complicating pregnancy; childbirth; or the puerperium.

This medical diagnosis code is frequently used in OB/GYN medical specialties to designate conditions such maternal disorders related to pregnancy.

Code Identity

ICD-10-CM Code
O24.019
Billable Status
Yes — Valid for Submission
Code Describes
Pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester
Short Description
Pre-exist type 1 diabetes, in pregnancy, unsp trimester
Parent Code
O24.01
Pre-existing type 1 diabetes mellitus, in pregnancy

Code Classification

ChapterO00-O9APregnancy, childbirth and the puerperium
SectionO20-O29Other maternal disorders predominantly related to pregnancy
CategoryO24Diabetes mellitus in pregnancy, childbirth, and the puerperium
This CodeO24.019Pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester

Code EditsBilling

Medicare Code Editor checks that affect claim validity for O24.019.

Maternity diagnoses
The Medicare Code Editor detects inconsistencies in maternity cases by checking a patient's age and any diagnosis on the patient's record. The maternity code edits apply to patients age ange is 9–64 years inclusive (e.g., diabetes in pregnancy, antepartum pulmonary complication).

Quality Payment Program MeasuresBilling

Medicare quality measures that can apply when O24.019 is part of the patient record.

Diabetes: Hemoglobin A1c (HbA1c) Poor Control (>9%)

High Priority: YES

Measure Type: Intermediateoutcome

Submission Methods: Claims, Electronic Health Record, Cms Web Interface, Registry

Description: Percentage of patients 18-75 years of age with diabetes who had hemoglobin A1c > 9.0% during the measurement period.

View Measure

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Pre-existing diabetes mellitus in pregnancy
  • Pre-existing type 1 diabetes mellitus
  • Pre-existing type 1 diabetes mellitus in pregnancy
  • Pregnancy and type 1 diabetes mellitus

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR END002
Diabetes mellitus without complication
Default principal diagnosis: inpatient No · outpatient No
CCSR END004
Diabetes mellitus, Type 1
Default principal diagnosis: inpatient No · outpatient No
CCSR PRG019
Diabetes or abnormal glucose tolerance complicating pregnancy; childbirth; or the puerperium
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Diabetes and Pregnancy

If you have diabetes, your blood glucose, or blood sugar, levels are too high. Glucose comes from the foods you eat. A hormone called insulin helps the glucose get into your cells to give them energy. With type 1 diabetes, your body does not make insulin. With type 2 diabetes, your body does not make or use insulin well.

The full article covers:

  • What is diabetes?
  • What is gestational diabetes?
  • Who is more likely to develop gestational diabetes?
  • How do I know if I have gestational diabetes?
  • How can diabetes affect my pregnancy?
  • How can I manage diabetes during pregnancy?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert O24.019 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
648.00 Diabetes in preg-unspec
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About O24.019Overview

Is O24.019 (Pre-existing type 1 diabetes mellitus, in pregnancy) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does O24.019 group to?

When pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester is the principal diagnosis on an inpatient stay, it groups to MS-DRG 817, 818, 819, 831, 832, 833, with relative weights from 0.5229 to 1.6880 depending on complications. Higher weights mean higher Medicare reimbursement.

Who can O24.019 be reported for?

The Medicare Code Editor checks pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.

What is the ICD-9 equivalent of O24.019?

Under the General Equivalence Mappings, pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester converts to ICD-9-CM 648.00 (diabetes in preg-unspec). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.