Racial/ethnic disparities in the prevalence of gestational diabetes mellitus by BMI

OBJECTIVE

To examine whether the association between gestational diabetes mellitus (GDM) and BMI category varies by racial/ethnic group.

RESEARCH DESIGN AND METHODS

In a cohort of 123,040 women without recognized pregravid diabetes who delivered babies between 1995 and 2006 at Kaiser Permanente of Northern California, we examined racial/ethnic disparities in the prevalence of GDM by BMI category and the population-attributable risk (PAR) associated with overweight/obesity.

RESULTS

Among all racial/ethnic groups, the age-adjusted prevalence of GDM increased with increasing BMI (kg/m²) category. However, Asian and Filipina women had a prevalence of GDM of 9.9 and 8.5%, respectively, at a BMI of 22.0–24.9 kg/m², whereas in Hispanic, non-Hispanic white, and African American women, the prevalence of GDM was >8.0% at a higher BMI, such as 28–30, 34–36, and ≥37 kg/m², respectively. The estimated PARs suggest that the percentage of GDM that could be prevented if all pregnant women were of normal weight (BMI <25.0 kg/m²) ranging from 65% for African American women to only 23% among Asian women.

CONCLUSIONS

Clinicians should be aware that the BMI thresholds for increased risk of GDM varies by racial/ethnic group and that the risk is high even at relatively low BMI cutoffs in Asian and Filipina women. Asian women may benefit from different prevention strategies in addition to weight management.Gestational diabetes mellitus (GDM) is carbohydrate intolerance with onset of or first recognition during pregnancy and is one of the most common pregnancy complications in the U.S. GDM is associated with increased risk for perinatal morbidity (1,2), and, in the long-term, women with GDM have an almost sevenfold increased risk of developing type 2 diabetes after pregnancy (3). The prevalence of GDM has increased in all racial/ethnic groups, and this has been observed in several populations in recent decades (4,5). Recent data suggest that the association between glucose and risk of adverse outcomes is continuous; gestational impaired glucose tolerance (IGT) is also associated with both pregnancy complications (6) and subsequent diabetes and cardiometabolic risk (7).Race/ethnicity and obesity are the two strongest independent risk factors for GDM (8–11). However, the demographic distribution of obesity (highest among African Americans and lowest among Asians) does not mirror the demographic distribution of GDM (lowest among African Americans and highest among Asians) (12). Yet there is ongoing debate surrounding the definition of overweight and obesity in Asian populations: the World Health Organization proposed a BMI cutoff of 23.0 kg/m² for overweight among Asians in 2000 (13), compared with a cutoff of 25.0 kg/m² for non-Asian populations. More recently, the World Health Organization stated that the definition of overweight in Asians likely varies depending on the outcome of interest (14). Currently, little is known about racial disparities in the risk of GDM by BMI categories.In a cohort of 123,040 women without recognized pregravid diabetes who delivered babies between 1995 and 2006 at Kaiser Permanente of Northern California (KPNC), we examined racial/ethnic disparities in the prevalence of GDM and IGT in pregnancy by BMI category and the estimated proportion of cases that could be prevented if overweight/obesity in pregnant women were eliminated (the population-attributable risk [PAR]).