Latinos in the United States have a higher lifetime risk of diabetes than those in other racial or ethnic groups (1). The age-standardized prevalence of diabetes among Mexican-American adults — the largest subgroup of US Latinos — is 20.1%, compared with 11.0% for non–Hispanic whites and 18.7% for non–Hispanic blacks (2). The prevalence of diabetes in the United States is expected to increase approximately 200% during the next 40 years, and this growing epidemic will continue to disproportionately affect Latinos (3). The magnitude of the diabetes burden among US Latinos, combined with this population’s rapid growth (4), underscores the relevance of identifying factors related to their diabetes risk.

Acculturation is the process whereby individuals from one culture adopt the behaviors, attitudes, and values of the prevailing culture (5). Acculturation has been measured by using validated instruments that explore this construct in-depth or widely available survey questions that serve as proxy measures for this complex social process (6). Studies have consistently demonstrated that acculturation is associated with worsening diet quality (7) and increased weight (8). Such evidence may suggest that acculturation is also positively associated with diabetes risk among Latinos, considering the role of obesity in the pathogenesis of type 2 diabetes. However, studies examining the relationship between acculturation and diabetes in Latinos have reported conflicting results, some showing that acculturation increases diabetes risk (9–12), and others showing no association (13–15). The lack of consistency in these findings may be due to differences in the study populations, or measurement of the exposure or outcome. The nature of the relationship between acculturation and diabetes in Latinos may have implications for the prevention, clinical care, and self-management of diabetes in this high-risk population.

By using data from the 2007–2010 National Health and Nutrition Examination Survey (NHANES), we examined the association between acculturation and diabetes. We used an acculturation score based on country of birth, predominant spoken language, and years of US residence. We also tested whether this association was mediated by body mass index, diet, and physical activity — factors that are influenced by acculturation and known to affect diabetes risk. Our study is the first to include a nationally representative sample of all US Latinos, whereas previous nationally representative studies have included only Mexican-Americans. Studying this novel population may provide further insight into the relationship between acculturation and diabetes in Latinos.

Our analysis of the NHANES data was deemed exempt from review by the Temple University Institutional Review Board. NHANES, which is conducted by the National Center for Health Statistics, uses a complex multistage probability sample designed to be nationally representative of the US civilian, noninstitutionalized population. Beginning in 2007, the NHANES sampling strategy was modified to oversample all Latinos, rather than only Mexican Americans, as in previous cycles (16). This modified sampling strategy allows for reliable national estimates of health indicators for all Latinos from 2007 to 2010, whereas previous cycles could yield reliable estimates only for Mexican Americans (16).

NHANES participants complete a home-based interview and a subsequent physical and laboratory examination in a mobile exam center. Procedures for blood collection and processing are described elsewhere (17). Of the 12,153 participants aged 20 years or older, 3,471 Latinos completed the household interview, 96.1% of whom underwent a physical and laboratory examination. The following numbers of Latino participants had glycemic testing as part of the laboratory examination: glycated hemoglobin (HbA_1c) (n = 3,185; 92%), fasting plasma glucose (FPG) (n = 1,621; 47%), and oral glucose tolerance test (OGTT) (n = 1,172; 34%).

We included adult Latinos who reported having received a doctor’s diagnosis of diabetes (n = 444), and those without doctor-diagnosed diabetes who had available data for HbA_1c (n = 2,721). We excluded participants in whom diabetes prevalence could not be determined — those without previously diagnosed diabetes who were missing HbA_1c data (n = 253). This accounted for 7.3% of the total Latino sample during this time period (unweighted). Pregnant women were also excluded (n = 53), leaving a final analytic sample of 3,165 Latino adults.

Overall, the prevalence of diabetes in our cohort was 12.4%. The prevalence at each acculturation level was as follows: lowest (35.2%), low (21.6%), high (12.4%), and highest (30.9%). Nearly two-thirds of study participants were of Mexican origin, more than half were aged less than 40 years, and nearly one-third achieved more than a high school education (Table 1). There were significant associations between diabetes and participant age, educational attainment, marital status, health insurance, usual source of care, BMI, total dietary calories, and physical inactivity (Table 1). The same participant characteristics, in addition to the income-to-poverty ratio, were significantly associated with acculturation (Table 2). The prevalence of obesity in our sample was 38.1%. BMI had a strong positive association with diabetes prevalence (Table 1). Although the association between BMI and acculturation was significant, the relationship was not linear (Table 2).

The unadjusted prevalence of diabetes by acculturation level was as follows: lowest (6.7%), low (20.5%), high (14.5%), and highest (12.5%). After adjusting for Hispanic origin, age, sex, insurance status, usual source of care, educational attainment, household income, and marital status, the likelihood of diabetes increased with the level of acculturation. Compared with those with an acculturation score of 0, the odds of having diabetes were 1.71 (95% confidence interval [CI], 1.31–2.23), 1.63 (95% CI, 1.11–2.39), and 2.05 (95% CI, 1.27–3.29) for those with acculturation scores of 1, 2, and 3, respectively. Adding BMI, total dietary calories, and physical inactivity to the fully adjusted model reduced the magnitude of the association between acculturation and diabetes only marginally, with this association remaining significant (Table 3, Model 4). Bootstrapped mediation testing confirmed that BMI is a partial mediator of this primary relationship, with the following coefficients (95% CIs) for the indirect, direct, and total effects: 0.049 (0.032–0.065), 0.132 (0.041–0.223), and 0.180 (0.084–0.277), respectively.

We conducted additional regression analyses for which results are not shown. When each proxy measure of acculturation was examined in a regression model without the other 2, each was associated with a significantly increased risk of diabetes after controlling for covariates.

In a nationally representative sample of US Latinos, the risk of diabetes was higher in those who were more acculturated, even after adjusting for demographic factors and socioeconomic status. The association between acculturation and increased diabetes risk remained significant after adjusting for BMI and weight-related behaviors in multivariable models. Mediation testing revealed that BMI only partially mediated this association between acculturation and diabetes.

This is the first study to examine the relationship between acculturation and diabetes in a nationally representative sample of all US Latinos. Previous NHANES studies on this topic did not involve a nationally representative sample of all Latinos because such a sample was assembled for the first time during the 2007–2010 waves of data collection. Combining all Latinos into 1 group presents both strengths and weaknesses when compared with the existing literature on acculturation and diabetes. Previous studies have documented differences in diabetes rates by Latino subgroup (20), which may provide an argument against aggregating all Latinos in one group. On the other hand, many hospital and clinic systems, government organizations, and other health care stakeholders report health data by Hispanic ethnicity, rather than by individual Latino subgroup. Therefore, many consumers of health data may find a sample of all Latinos more useful in representing their diverse Latino populations in many US communities (21).

Another strength of our study is that we examined undiagnosed diabetes, rather than only including those with doctor-diagnosed diabetes. An HbA_1c value of 6.5% or higher was used to classify those with undiagnosed diabetes — an approach that has been formally recommended for diagnosing diabetes by both national and international authorities and is commonly used for that purpose in clinical practice (22). Because those with undiagnosed diabetes constituted almost one-quarter of our sample with diabetes, previous studies that did not examine undiagnosed diabetes or used a different HbA_1c cut-off may have been biased by misclassification (11,12).

The cross-sectional nature of this analysis precludes drawing causal inferences about the relationship between acculturation and diabetes. NHANES does not collect data on whether individuals have type 1 or type 2 diabetes. However, on the basis of other studies, more than 90% of cases in NHANES are likely to be type 2 diabetes (23). Using HbA_1c as the diagnostic criterion for undiagnosed diabetes limits direct comparison of these findings to other studies that used different diagnostic tests. Although Latinos have higher HbA_1c levels than non–Hispanic whites (24), this difference would not be likely to affect the associations we found in our study between acculturation and diabetes among Latinos. Our acculturation score used the 3 most widely used proxy measures for acculturation (5), but the score does not assess all aspects of acculturation, some of which may be related to the risk of diabetes. For example, NHANES does not assess cognitive, emotional, or structural factors that are part of the acculturation process, and some detailed questions in NHANES on language use were not included in the 2007–2010 surveys. More complex measures including other dimensions of the acculturation experience have been developed, but are not available in NHANES or other national data sets.

Our findings are consistent with those of 4 other studies showing that the risk of diabetes increases with acculturation among Latinos (9–12). Only one of these other studies was nationally representative (11), and another found this risk only among Latinos who were not of Mexican ancestry (9). Other studies have found no significant association between acculturation and diabetes among Latinos (13–15). Our findings may have differed from those of other studies using NHANES data that only included Mexican Americans (14,15). In addition, conflicting reports about acculturation and diabetes in US Latinos may reflect the changing nature of this relationship over time as diabetes has become more common in Latin America and is present in more Latinos before they leave their home countries (25).

A novel finding in this study is that BMI and weight-related diet and physical activity behaviors explain only a small proportion of the relationship between acculturation and diabetes risk in Latinos. Like other covariates in our analysis, the association between BMI and acculturation was significant but nonlinear, which may partly explain its small effect on our multivariate mediation model. However, this relatively small contribution of BMI and weight-related behaviors to the relationship between acculturation and diabetes prompts consideration of other bio-behavioral mechanisms underlying this association. The stressful impact of acculturation on immigrants, or “acculturative stress” (26), may cause adverse metabolic consequences unrelated to BMI that contribute to the positive association found here between acculturation and diabetes. Experimental evidence from both animal and human studies has linked the perception of stress with physiologic responses that are harmful to health (27). This physiologic stress response, which involves activation of the hypothalamic-pituitary axis and chronic inflammation, has been implicated in the development of type 2 diabetes (28). A recent NHANES study reported unhealthier inflammatory and metabolic profiles, including HbA_1c, among US-born versus foreign-born Mexican Americans (29).

A recent study revealed significant heterogeneity in diabetes risk among Latino subgroups (20), which may stem in part from their different acculturation experiences in the United States. Future research should explore the relationship between acculturation and diabetes among all major Latino subgroups separately. Longitudinal studies of Latinos should explore biologic correlates of acculturation — including physiologic markers of psychological stress — and their associated diabetes risk, which may imply a causative role for acculturation in diabetes incidence. Large survey studies should include standardized, validated instruments to measure acculturation, which would facilitate interpretation of study findings and comparisons across studies. Qualitative research in this area may serve as an important complement to epidemiologic studies by exploring the process of acculturation in more depth than is possible using standard survey questions. Using such knowledge about Latino culture in health care interactions may improve providers’ efforts to address diabetes in the clinical setting (30). Therefore, future studies that examine the social context surrounding acculturation and diabetes in US Latinos may provide unique insights into how to prevent and treat diabetes in this high-risk population.