November 3, 2025

Gestational Diabetes

Gestational Diabetes Definition

Any pregnant person that shows abnormal glucose tolerance that was not present prior to the pregnancy. The American College of Obstetricians and Gynecologists (ACOG) define GDM as "a condition in which carbohydrate intolerance develops during pregnancy.” Preexisting (pregestational) diabetes refers to type 1 or 2 diabetes diagnosed before pregnancy. 


Common Risk Factors: 

  • GDM in a prior pregnancy 
  • Family history of diabetes 
  • Pre-pregnancy BMI ≥30 kg/m2, significant weight gain in early adulthood or between pregnancies, or excessive gestational weight gain during the first 18 to 24 weeks of pregnancy 
  • Maternal age >/=35 years of age 

 

Key Points for Accurate Documentation 

 

  • Specify Diagnosis Clearly 
  1. Use the term “Gestational Diabetes Mellitus (GDM)” and indicate if it is diet-controlled (A1) or insulin/medication-controlled (A2). 
  2. Avoid vague terms like “borderline diabetes” or “glucose intolerance.” 
  • Document Diagnostic Basis 
  1. Include OGTT results or note that diagnosis was based on ADA/ACOG criteria (e.g., abnormal 1-hour or 3-hour glucose tolerance test). 
  • Capture Clinical Significance 
  1. Note any maternal or fetal complications (e.g., polyhydramnios, macrosomia, preeclampsia). 
  2. Document treatment plan: diet modification, insulin, oral agents, or glucose monitoring. 
  • Differentiate from Pre-existing Diabetes 
  1. Confirm that hyperglycemia was first recognized during pregnancy. If diabetes existed before pregnancy, code as pre-gestational diabetes. 
  • Postpartum Follow-up 
  1. Indicate if postpartum glucose testing or counseling for future diabetes risk was provided. 

 

Why It Matters: 

Precise documentation supports accurate ICD-10 coding (e.g., O24.41–O24.43), reflects severity of illness, and impacts quality metrics and reimbursement. AHRQ’s Maternity Care Measure Set includes post-partum glucose careening for gestational diabetes patients in Measure 10 – Post-Partum Follow-up and Care Coordination. This measure applies to all patients regardless of age, who gave birth during a 12-month period seen for post-partum care visit before or at 8-weeks of giving birth. There are no exceptions. 


Alyce Reavis, RN,MSN,CCDS,CCS Senior CDI Educator, Consulting Services at UASI

Alyce Reavis, RN,MSN,CCDS,CCS 

Senior CDI Educator, Consulting Services at UASI


Drawing on clinical experience in adult, pediatric, and neonatal acute care, Alyce brings valuable insight to CDI education and documentation improvement. She holds an MSN in Leadership/Education along with CCDS, CCS, and AHIMA’s outpatient CDI micro credential, supporting health systems in strengthening documentation accuracy, quality reporting, and reimbursement integrity. Passionate about truthful, clinically aligned health records, she helps organizations ensure documentation reflects true patient acuity. She is a past presenter for the ACDIS National Convention, Local chapter meetings, and the ACDIS Virtual Best Practices conference. 



Works Cited:

ACOG / National Committee for Quality Assurance. (2012). Maternity Care Performance Measures Set.
Available at https://www.ahrq.gov/sites/default/files/wysiwyg/CHIPRA-BMI-Maternity-Care-Measures.pdf


American College of Obstetricians and Gynecologists. (2018). Gestational Diabetes Mellitus (Practice Bulletin No. 190).
Available at https://www.acog.org/clinical/clinical-guidance/practice-bulletin/articles/2018/02/gestational-diabetes-mellitus


Centers for Medicare & Medicaid Services. (2025). Official Guidelines for Coding and Reporting: ICD-10-CM, FY 2026.
Available at https://www.cms.gov/files/document/fy-2026-icd-10-cm-coding-guidelines.pdf


American Diabetes Association. (2025). Management of Diabetes in Pregnancy. Diabetes Care, 48(Supplement 1), S306–S320.
Available at https://diabetesjournals.org/care/article/48/Supplement_1/S306/157565/15-Management-of-Diabetes-in-Pregnancy-Standards


Durnwald, C. (2025). Gestational diabetes mellitus: Screening, diagnosis, and prevention. UpToDate.

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