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Comparing Metformin and Insulin for Gestational Diabetes Treatment

DECIDE: A Comparative Effectiveness Trial of Oral Metformin Versus Injectable Insulin for the Treatment of Gestational Diabetes

Phase 4 Interventional Ohio State University · NCT06445946

This study is testing whether metformin is as effective as insulin for treating gestational diabetes in pregnant people and looks at how safe both treatments are for mothers and their babies.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment1572 (estimated)
Ages18 Years and up
SexFemale
SponsorOhio State University Academic / other
Locations21 sites (Tuscaloosa, Alabama and 20 other locations)
Trial IDNCT06445946 on ClinicalTrials.gov

What this trial studies

This trial compares the effectiveness of metformin versus insulin in treating gestational diabetes mellitus (GDM) in pregnant individuals. It is a randomized controlled trial involving 1,572 participants across 20 U.S. sites, focusing on whether metformin is as effective as insulin in reducing adverse pregnancy outcomes. The study also aims to assess the safety of both treatments for mothers and their children, as well as to explore patient-reported experiences regarding the use of these medications. Participants will be followed from pregnancy through two years postpartum to gather comprehensive data.

Who should consider this trial

Good fit: Ideal candidates for this study are pregnant individuals aged 18 and older diagnosed with gestational diabetes who require medication for glucose control.

Not a fit: Patients with renal disease, major fetal malformations, or contraindications to metformin or insulin will not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide evidence that metformin is a safe and effective alternative to insulin for managing gestational diabetes, potentially improving treatment options for patients.

How similar studies have performed: Previous studies have indicated that both metformin and insulin are effective for managing gestational diabetes, but this study aims to provide more definitive comparative effectiveness data.

Eligibility criteria

Show full inclusion / exclusion criteria 
Inclusion Criteria:

* Singleton gestation. Twin reduction to singleton, either spontaneously or therapeutically, is eligible if it occurred before 14 weeks gestational age.
* Age 18 years or older
* Gestational age at randomization between 20 0/7 - 33 6/7 weeks based on project gestational age.
* GDM diagnosis less than or equal to 33 6/7 weeks based on project gestational age.
* Requires medication for glucose control defined as ≥ 30% elevated glucose values (either fasting or postprandial or both) prior to randomization per determination of the provider or documented in the medical record.
* Patient willingness and ability to attend 2-year follow-up visit.

Exclusion criteria:

* Renal disease (serum creatinine \>1.3 mg/dL) due to the potential impact of metformin on renal function.
* Major structural malformation of the fetus.
* Known fetal aneuploidy based on invasive testing or positive for aneuploidy on cell-free fetal DNA screening.
* Contraindication to metformin or insulin, including: history of lactic acidosis, intractable nausea and vomiting, prior documented allergy and/or anaphylaxis.
* For individuals with GDM diagnosed \<20 0/7 weeks, documented A1c ≥\>6.5% within prior 6 months.
* Pregestational diabetes documented in the medical record or prior A1c\>= 6.5%
* Fasting hyperglycemia \>115 mg/dl for ≥ 50% of fasting glucose values in the past week (due to the high risk of metformin failure with fasting hyperglycemia).
* Enrolled in a trial that influences primary study outcomes (composite neonatal outcome at delivery or childhood body mass index at 2 years).
* Prenatal care or delivery planned at a location where access to the complete electronic medical record will not be available to research staff.
* Language barrier (appropriate translation resources unavailable at the site)
* Participation in this trial in a previous pregnancy. Patients who were screened in a previous pregnancy, but not randomized, may be included.

Where this trial is running

Tuscaloosa, Alabama and 20 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
View on ClinicalTrials.gov → Find more trials like this →
Conditions Gestational Diabetes MellitusPregnancy, High RiskInsulinPregnancyGlycemic controlMetforminGestational diabetesDiabetes
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.