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BackgroundDiabetes is a kind of common and chronic lifelong disease. As a cause of disability and mortality, diabetes ranks third, just below cancer and cardiovascular disease. The prevalence of diabetes is increasing with the development of the economy and the change of life style. In China, about95%diabetes patients develop type2diabetes mellitus. According to the prediction of the WHO, there will be about300million patients with diabetes all over the world by2025, most of which will be in China, the subcontinent of India and Africa. Owing to this situation, we can draw the conclusion that the worsening situation of diabetes is becoming a serious public health problem. Type2diabetes, symptoms of which are chronic high blood glucose and hyperinsulinemia, results from insulin resistance with relatively low insulin production, or from the body’s failure to produce insulin with or without insulin resistance. Type2diabetes can cause many chronic complications, such as cardiovascular disease, chronic renal failure, diabetic retinopathy and nerve injury. This polygenetic disease is caused by the interaction of genetic and environmental factors, in which the latter are more important. Diabetes itself is not transmitted to next generation. The one transmitted is the susceptibility of diabetes, which causes the disease with the effect of environmental factors. Previous studies paid attention to the relationship between age/smoke and diabetes. Many epidemiological and clinical results show that obesity, type2diabetes, hyperlipidemia and hypertension always co-exist. Research shows that blood pressure is associated with diabetes, with a positive correlation between blood pressure and blood glucose levels. Foreign and domestic studies have found an find the association between normal serum lipids and type2diabetes.Recently, with the completion of the human genome project and the development of functional genomics, a set of susceptibility gene loci were found, abstracting the attention of researchers. Such loci are the genes for leptin, angiotensin converting enzyme, calpain, interleukin-6, TNF-a and the target genes of the current research, the adipoQ gene and insulin receptor gene, etc.Related studies have indicated that prevalences of diabetes are different among different races. The hypertension prevalence in the Yi people is the lowest in China. Since diabetes is associated with hypertension, we could infer that the prevalence of diabetes in the Yi people is probably low as well. The Liangshan Yi autonomous prefecture is located in south-western Sichuan province, with0.601million square kilometers and17counties. There are Yi, Han, Meng, Zang, Hui and other ethnic people living in this area, with a total population of41.55million. With20million Yi people in this area (43.6%), the Liangshan Yi prefecture has the largest population of Yi in China. The Yi people live in remote mountain areas with genetic isolation. Recent decades, some emigrate to towns and cities, offering an important natural field for migration epidemiology research.ObjectiveThe current migrantion epidemiologic research carried out in Yi and Han people to understand prevalence of diabetes in Yi and Han people in liangshan area. This study focused on the prevalence and risk factors for diabetes in the Yi and Han people in the Liangshan Yi prefecture. By comparison of prevalence and risk factors among Yi farmers, Yi migrants and Han people, this study may provide some suggestions to prevent T2DM.MethodsThis is a cross-sectional study on T2DM in Yi and Han people in the Liangshan area (including Xichang, Jinyang, Zhaojue, Butuo, Xide, Deyang and Ningnan), Sichuan, China. A sample of2878Yi people (Yi farmers:1549, Yi migrants:1329) and2150Han people were selected. Questionnaire survey, anthropometric measurement and blood test were carried out. For the further purpose to explore the association between adipoQ/insulin receptor genes and type2diabetes in Yi and Han people. All the type2diabetes patients were for the case group, and healthy controls were randomly and frequently matched by race, age and sex. PCR-RFLP was used to test the target gene in case and control group.ResultsThe prevalence of T2DM in Yi farmers is4.33%(male:6.15%, female:2.89%), and that of Yi migrant is9.03%(male:11.31%, female:5.81%). The prevalence of T2DM in Han people is7.58%(male:7.34%, female:7.83%). Yi farmers have the lowest total prevalence of T2DM and Yi migrants have the highest prevalence. Among female participants, Yi farmers have the lowest prevalence and Han people have the highest. For males, it is lowest in Yi farmers and highest in Yi migrants. Yi farmer females have the lowest prevalence and Yi migrant males have the highest. For Yi farmers and migrants, the prevalence of T2DM in males is higher than in females. In Han people, the prevalence is not significantly different between males and females. The age standardized prevalences among Yi farmers, Yi migrants and Han people(4.01%,8.88%and6.22%respectively) are significantly different. The standardized prevalence in Yi migrant male is10.35%, significantly higher than in Yi farmer and Han people males. The prevalence in Yi farmer females is2.41%, significantly lower than in the other two groups. Comparison made in different groups by race and sex shows that the standardized prevalence T2DM in female Yi farmers is the lowest, and is significantly different from the other five groups. The age-and sex-standardized prevalences among Yi farmers, Yi migrants and Han people are4.26%,8.41%and6.08%, respectively and the significant difference is observed between Yi farmers and migrants. Multivariate analysis shows that age, sex, hypertension and abnormal TG level are the risk factors for type2diabetes, and in Yi people drink is a protective factor. The associated factors in Yi farmers are age, sex, hypertension, BMI, drink and TG, and drink is a protective factor as in Yi people. For Yi migrant, age, blood pressure and HDL-c lower level are the risk factors for type2diabetes, as well as time before and after emigration. In Han people, only age and HDL-c are associated with T2DM. In Yi farmer females, no associated factors are found. ConclusionsThe prevalence of T2DM in Yi farmers is lower than the national level in the same period. After emigration, with the life style urbanization, the prevalence of type2diabetes goes up significantly and becomes even higher than in Han people. Age, sex, blood pressure, blood lipid, body weight and drink are associated with T2DM. Association between the target SNPs and T2DM in the research group is not significant.
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