Of many proxies for acculturation, duration of US residence is one of the most frequently used indicators in the literature on immigrant health (see a review paper done by Lara et al. 2005). Prior studies that used length of residence typically assumed that longer duration of stay is correlated with higher levels of acculturation. From this perspective, researchers posit that immigrants’ favorable health upon arrival erodes with additional years in the country, converging to native-born levels, as they adopt unhealthy lifestyles of the US population (Scribner 1996; Jasso et al., 2004). For instance,
immigrants with longer duration of residence are more likely to be a current smoker and smoke more frequently than those who have spent less time in the country (Abraido- Lanza et al., 2005; Gorman, Read, & Krueger, 2010; Kimbro, 2009). This negative effect of duration has been reported with alcohol consumption (Abraido-Lanza et al., 2005; Lopez-Gonzalez, Aravena, & Hummer, 2005), chronic conditions (Singh and Siahpush 2002), high BMI or being overweight/obese (Antecol & Bedard, 2006; Bostean, 2013b), activity limitations (Cho, Frisbie, Hummer, & Rogers, 2004), allostatic load (Peek et al., 2010), acculturative stress (Devylder et al., 2013) and self-reported health (Kimbro, Gorman, & Schachter, 2012). In contrast, several studies have also found that longer duration of US residence to be beneficial, including increased earnings, better English proficiency, access to healthcare and knowledge on US healthcare system (Chesney et al. 1982; Kaushal and Kaestner 2013; Marks, Garcia, and Solis 1990; O’Malley et al. 1999; Pérez-Stable, Marín, and Marín 1994; Wong, Díaz, and Higgins 2006). Because health
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behaviors and using healthcare services are directly associated with the development and detection of diabetes, it is expected that a large share of variation between foreign-born individuals in terms of diabetes and undiagnosed diabetes could be captured when duration of residence is accounted for.
Given a positive association between length of residence and several health indicators that are key risk factors for diabetes, such as BMI (Gregg et al., 2004), smoking (Willi, Bodenmann, Ghali, Faris, & Cornuz, 2007) and psychosocial stress (Kelly & Ismail, 2015), it is logical to assume that immigrants with longer US duration have a higher risk of diabetes than recent arrivals. Although findings vary depending on study designs, prior studies in general reported a positive relationship between longer duration of US residence and the prevalence of diabetes. Riosmena, Wong and Palloni (2013) found that Mexican immigrants with 15+ years of duration of residence in the US had a significantly higher risk of reporting self-reported diabetes than those with <5 years of duration. However, there were no significant differences between 5-9 years and 10-14 years, and <5 years of duration of stay. Horlyck-Romanovsky et al. (2019) reported a significant difference in the odds of self-reported diabetes between foreign-born blacks with less than 10 years of US residence and those with 10 years or longer stay. Another national study using NHIS waves of 1997-2005 found an increase in adjusted prevalence of diabetes with increased length of residence in the United States, independent of BMI (Oza-Frank, Stephenson and Narayan, 2011). One study that measured diabetes based on fasting glucose level and the use of diabetes medication found that immigrants living in the US for 20 years or longer had a higher adjusted risk of incident diabetes than those
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with less than 20 years of duration of stay, but this study is limited to a small sample size and focuses on incident diabetes only (Oza-Frank et al., 2013).
Most of these studies focused on self-reported diabetes. As discussed earlier, using self-reported diabetes is subject to a underreporting problem, which leads to an underestimation of the actual prevalence of diabetes among immigrants. Using a variety of measures of diabetes, such as self-reported diabetes, biomarkers of diabetes and undiagnosed diabetes, can help to elucidate how duration of stay may be correlated with diabetes. First, immigrants with a longer duration of stay may have an increase in the risk of diabetes if they adopt unfavorable US health behaviors, i.e., cigarette smoking and unhealthy diet, over time. This process results in an increase in the prevalence of both self-reported diabetes and diabetes identified by biomarkers. Second, as immigrants have improved healthcare access and better health insurance with increasing duration of residence, the immigrants can have a better chance of finding out their diabetes status, resulting in an increase in detected cases and thus an increase in the prevalence of self- reported diabetes, regardless of changes in the actual incidence of the disease in this population (Antecol & Bedard 2006; McDonald and Kennedy 2004). Lastly, given that a longer duration of stay is associated with access to preventive healthcare and timely screening of diabetes, the prevalence of diabetes may not be associated with longer duration of US residence.
It is likely that all three pathways operate at the same time offsetting each other, attenuating the reliability of the association between duration of stay and diabetes. One way to avoid this problem is to further estimate the association between time in the US and biomarkers for diabetes and undiagnosed diabetes. If the second scenario is true, the
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prevalence of diabetes identified by biomarkers would remain constant over time, while the prevalence of self-reported diabetes among the foreign-born would increase with the decrease in undiagnosed diabetes.