Diabetes is a major problem around the world. The reason why diabetes is such a problem is most likely due to the mismatch between our ancestral environments and modern environments. Modernization and urbanization along with technology has led to changes in our environment. For example, the development of myopia or shortsightedness is due to the increase in near work. Also, the increase availability of foods has led to change in dietary habits, which has placed an increase emphasis on the development of diabetes. Given the environmental aspect, it's also important to consider the genes involved. Genomics has helped a lot in the aspects of preventative medicines because it allows us to associate gene variants with susceptibility to disease. Most importantly, how these gene variants interact with environmental factors could tell us lot about how a disease develops in an individual. This is where epidemiology becomes important because it allows us to consider environmental and social factors that could influence disease development. Also, many genes are involved in this development of this disease and linkage of these genes plays a major role in diabetes development as well. Finally, it's important to see how these genes interact with us and how a problem with a gene can influence notable symptoms reminiscent of diabetes.
Genes and environment
Susceptibility of diabetes in Southeast Asia is influenced by mutations next to or within genes. Most of these genes have complex traits that interact and control multiple systems in the body. The genes are important, but they alone do not influence diabetes in this population. Westernization and globalization in Asia have led to changes in food supply and dietary patterns, coupled with risk alleles in genes of interest. Foods with high glycemic index, such as rice, have contributed to an increased risk of type 2 diabetes. These high glycemic foods, coupled with loss of gene function, have led to increase in blood glucose levels in Japanese populations. Researchers have used Genome Wide Association Studies (GWAS) to identify several genetic variants of genes that are found in white and Asian populations; however, they found that there are interethnic differences in risk allele frequency of these genes and the location of those mutations.
Epidemiology
Age and gender are critical variables to track diabetes within a population overtime. Another very important factor of diabetes development is the environment in which that population lives. Factors like smoking or alcohol consumption has been seen to be prevalent in Japanese populations. For example, smoking was very prominent in Japan in the 1980s where 40% of the population smoked. As of 2020, smoking has declined to around 16% of the population. The more resounding knowledge on the effect of smoking and the link to disease susceptibility has most likely driven this decline. Smoking generally leads to problems because it leads to insulin resistance and/or decrease insulin secretion.
Genes involved
Many diabetic studies have tried to deduce as to what and how many genes are involved in susceptibility to disease in Japanese populations. Researchers use tools such as GWAS and quantitative trait loci (QTLs), which can be very helpful in determining what mutations are associated with disease in a population. Most of these mutations are called single nucleotide polymorphisms (SNPs) leading to different variants of a gene, and these mutations can be different or the same across varying populations. If they are the same mutations, a population could have varied allelic frequencies of the gene or genes that lead to that disease. For example, a genetic variation of TCF7L2 in Japanese population influences one’s susceptibility to diabetes; however, the at-risk allele frequency in Japanese population accounted for 4% of the population compared to 21% in European and European-origin population.