GDM Rates in American Samoa: New Study Seeks Answers

What This Study Found

Researchers have launched a major new study called GROW (Gestational Diabetes — Risk Factors and Outcomes among American Samoan Women) to understand why gestational diabetes mellitus (GDM) is so common in American Samoa. Estimates suggest that between 26% and 42% of pregnant women there develop GDM — one of the highest rates anywhere in the world. This study protocol lays out how scientists plan to track 350 pregnant women from early pregnancy through 18 months after birth to find answers.

Why This Matters for You

Gestational diabetes is not just a pregnancy concern. It raises the risk of type 2 diabetes (T2DM) for the mother later in life and can affect a baby's long-term health too. Despite how common GDM is among Pacific Islander women, no studies have ever looked closely at why these women are at such high risk — or whether their biology plays a unique role. The GROW study is the first to do that.

What the Researchers Will Do

Starting in the first trimester, 350 women in American Samoa will be enrolled and followed closely. Researchers will use several tools to track blood sugar patterns, including:

• Oral glucose tolerance tests (OGTTs) — to measure how the body handles sugar
• HbA1c blood tests — to check average blood sugar over time
• Continuous glucose monitors (CGMs) — small wearable sensors that track blood sugar around the clock

Participants will also answer questions about their diet, physical activity, sleep, and mental health.

The Gene Factor: What Is CREBRF?

One of the most exciting parts of this study is its focus on a gene variant called CREBRF rs373863828. This variant is found almost exclusively in Pacific Islander populations and is known to have a protective effect against type 2 diabetes. However, it is also linked to higher body weight — which is itself a risk factor for GDM. Researchers want to understand whether this gene helps or complicates blood sugar control during pregnancy.

This kind of research is called precision medicine — tailoring prevention and treatment to an individual's biology, background, and community. If scientists can identify who is most at risk and why, doctors can offer more targeted support.

Important Note About This Study

The GROW study has not yet published results — this article describes the study design, published as a preprint in 2025. The findings will come in future years as data is collected and analyzed.

What This Could Mean Going Forward

Results from GROW are expected to help shape clinical guidelines and public health programs specifically for Pacific Islander women — a population that has long been underrepresented in diabetes research. Better understanding of GDM in this group could lead to earlier screening, more effective prevention, and healthier outcomes for mothers and babies.

If you are managing gestational diabetes or concerned about your risk of type 2 diabetes after pregnancy, blood sugar monitoring tools — like those available at mdsdiabetes.com — can play an important role in staying on top of your health.

Citation: Carson, Faasalele-Savusa, Loia (2025). Gestational Diabetes — Risk Factors and Outcomes among American Samoan Women (GROW): A Longitudinal Cohort Study Protocol. medRxiv: the preprint server for health sciences. PMID: 41282747. DOI: 10.1101/2025.10.24.25338761. Note: This is a preprint and has not yet been peer-reviewed.