Bold claim: gestational diabetes is a hidden accelerator of health risk for American Samoan women, and new research aims to untangle why this condition hits so hard and so early. But here’s where it gets controversial: could genetic differences and early pregnancy biology be driving differences in diabetes risk that aren’t fully captured by standard screening? This is the question at the heart of a new study from Yale and partners that seeks to answer with unprecedented depth and initial hope.
A study led by the Yale School of Public Health, titled Gestational Diabetes - Risk Factors and Outcomes among American Samoan Women (GROW), is examining gestational diabetes in pregnant American Samoan women—an group facing markedly higher risk for this condition. GROW stands as the first long-term, population-specific investigation into why Pacific Islander women experience such high rates of gestational diabetes and why a subset progresses rapidly to type 2 diabetes after delivery. The study protocol has recently appeared as a preprint on medRxiv.
We anticipate that GROW will yield practical insights in several ways. By identifying early biological and behavioral indicators of risk in this relatively understudied population, researchers hope to refine targeting of prevention efforts to those most in need, based on data gathered very early in pregnancy.
Gestational diabetes mellitus (GDM) is glucose intolerance that first surfaces during pregnancy. While it raises the risk of complications for both mother and baby during pregnancy and birth, it also elevates the likelihood that the mother will develop type 2 diabetes later in life. In a typical pregnancy, rising blood sugar supports fetal growth, and the body normally compensates by increasing insulin production. When this compensatory response falls short, GDM emerges.
Risk factors for GDM include age, family history of diabetes, obesity, and high blood pressure. However, some populations face substantially higher risk. Early findings from Hawley’s work suggest that GDM prevalence in American Samoa could be as high as 40%, compared with around 9% in the U.S. population more broadly.
Despite the substantial burden, the roots of GDM among Pacific Islander communities remain poorly understood. GROW aims to fill that knowledge gap.
Nicola Hawley, PhD, associate professor of epidemiology (chronic diseases) at Yale, explains that the project unites researchers from the University of Pittsburgh, Emory University, and the Obesity, Lifestyle and Genetic Adaptations (OLaGA) Research Center in American Samoa. The team plans to enroll 350 Samoan women early in pregnancy and follow them for 18 months after birth. They will deploy cutting-edge tools—including continuous glucose monitoring, advanced oral glucose tolerance testing, and genetic analyses—to track how glucose regulation shifts before, during, and after pregnancy.
A central focus is the CREBRF gene variant (rs373863828), carried by roughly 40% of Samoan individuals. This variant is linked to higher body weight but, interestingly, a lower risk of developing type 2 diabetes. Early data hint that it may even confer protection against gestational diabetes. GROW will be the first program to closely investigate how this gene variant influences insulin production, glucose control, and overall diabetes risk in pregnancy—a period described as a natural metabolic stress test for the body.
By coupling high-quality metabolic measurements with postpartum follow-up, the study will also explore who develops pre-diabetes or type 2 diabetes after pregnancy and why. The findings could inform new clinical guidelines, community-based diabetes prevention initiatives, and precision-medicine approaches tailored to Pacific Islander communities. Hawley notes that the timing of screening might need adjusting for this population; standard practice screens between 24 and 28 weeks gestation, but earlier screening could be more effective here.
The team hopes the results will improve screening recommendations and treatment strategies going forward.
Implementing novel methods in a low-resource setting has presented challenges. American Samoa’s warm, humid climate complicates long-term use of continuous glucose monitors, particularly the adhesive patches required for a 10-day wear. The project forged a new partnership with Not Just a Patch, an Australian company that provides waterproof sensor patches and now supports the study’s need for reliable monitoring in tropical conditions. Hawley remarks that the company founder’s lived experience with type 1 diabetes brought valuable guidance, and in return the collaboration aims to generate data that could benefit Not Just a Patch as it expands into similar climates and markets.
In short, GROW seeks to transform understanding of gestational diabetes in American Samoan women, with potential ripple effects for screening timing, prevention programs, and personalized care for Pacific Islanders.
Author: Michelle So
Tags: Health Disparities, Diabetes, Global Health, Genetics, Maternal Health
Learn more: Yale Institute for Global Health in Samoa
