O24.011 Pre-existing type 1 diabetes mellitus, in pregnancy, first trimester

ICD-10-CM O24.011: Pre-existing type 1 diabetes mellitus, in pregnancy, first trimester

ICD-10-CM code O24.011 identifies pre-existing type 1 diabetes mellitus occurring during the first trimester of pregnancy. Type 1 diabetes involves the body not producing insulin, leading to elevated blood glucose levels. Pre-existing diabetes in pregnancy increases risks of adverse maternal and neonatal outcomes. 1 2 3

Plain-language overview

Type 1 diabetes is a condition where the body does not make insulin, causing blood glucose levels to become too high, and this diagnosis applies when such pre-existing diabetes occurs during pregnancy. 3 1

What this code represents

The code O24.011 represents the diagnosis of pre-existing type 1 diabetes mellitus in pregnancy, specifically during the first trimester, and its terminology record is currently active. 1

O24.011 is classified as a Disease or Syndrome and falls under the parent concept O24.01, which covers pre-existing type 1 diabetes mellitus in pregnancy. 1

Clinical context

The presence of pre-existing type 1 diabetes in pregnancy increases the risk of adverse maternal and neonatal outcomes, including preeclampsia, caesarian section, pre-term delivery, macrosomia, and congenital defects. 2

Women with type 1 diabetes should undergo retinal examination ideally prior to conception or within the first trimester to screen for diabetic retinopathy. 2

Documentation considerations

The terminology record for O24.011 includes the full preferred name of pre-existing type 1 diabetes mellitus, in pregnancy, first trimester, along with a published abbreviation of the same phrase. 1

Coding details

The O24.011 terminology record has narrower concepts, and a separate code O24.019 exists for pre-existing type 1 diabetes mellitus in pregnancy when the trimester is unspecified. 1 4

What the sources add

While the terminology record defines the code structure, clinical literature adds that pre-existing type 1 diabetes in pregnancy increases risks for adverse outcomes like preeclampsia and congenital defects. 1 2

A clinical review provides operational context by recommending first-trimester retinal examinations for women with type 1 diabetes, while the terminology record establishes the first-trimester timeframe for this code. 2 1

Sources

1. ICD-10-CM O24.011 terminology record — National Cancer Institute Enterprise Vocabulary Services; accessed 2026-07-27.
2. Management of preexisting diabetes in pregnancy: A Review — pmc.ncbi.nlm.nih.gov; accessed 2026-07-27.
3. O24.011 — Pre-existing type 1 diabetes mellitus, in pregnancy, first trimester | ICD-10 Code · Eleplan — eleplan.com; accessed 2026-07-27.
4. O24.019 - Pre-existing type 1 diabetes mellitus, in pregnancy, unspecified trimester | ICD-10-CM — unboundmedicine.com; accessed 2026-07-27.