Metabolic changes in immigrants from Africa to a Western country: Time-lag effects of 20 years since immigration

Background: An increase in the prevalence of type 2 diabetes mellitus occurs in immigrants from developing regions to Western countries. However, the dynamics of these transitions in relation to the duration of residence in the new environment are not clearly defined. Methods: Data concerning cardiovascular risk factors were retrospectively extracted from medical charts of 736 Ethiopian immigrants and 575 randomly-chosen, age and sex matched non-Ethiopian subjects ("reference group"). Ethiopian immigrants were designated "established" (≥20 years of residence), "intermediate" (10-15 years of residence), or "recent" (<10 years of residence). Results: Compared to non-Ethiopians, the age- and sex-adjusted odds ratio (OR) for diabetes was 1.00 (95%CI: 0.66-1.49) for established, 0.55 (95%CI: 0.29-1.03) for intermediate, and 0.15 (95%CI: 0.04-0.50) for recent immigrants (P<0.001). The corresponding OR for hypertension was 0.94 (95%CI: 0.68-1.31), 0.42 (95%CI: 0.26-0.69), and 0.14 (95%CI: 0.06-0.30) for the established, intermediate, and recent immigrants respectively (P<0.001). In contrast to the gradual increase in prevalence of diabetes and hypertension, the Ethiopian immigrants maintained their lower body mass index (BMI) (28.7±5 vs 25.5±5kg/m² respectively, P<0.001) and serum low-density-lipoprotein cholesterol (129±36 vs 118±34mg/dL, P<0.001) compared to the non-Ethiopians even after 20 years of residence in Israel. Conclusions: The prevalence of diabetes and hypertension among the immigrants increased to about half that of the local population within 15 years and became equal to that of the local population after a time-lag of 20 years. These metabolic derangements occurred despite maintaining desirable BMI levels, reinforcing the need for re-defining optimal BMI ranges in relation to the ethnic origin.