AsianScientist (May 12, 2016) – Researchers from the University of Adelaide have shown how the global increase in cases of Type 1 diabetes is directly linked to advances in medical care. With an increased life expectancy, the underlying genetics of the disease are more likely to be passed from one generation to the next.
This study, published in BMJ Open Diabetes Research & Care, involved data for Type 1 diabetes only and has no relevance for Type 2 diabetes in the population.
In the present study, researchers looked at the prevalence of Type 1 diabetes in 118 countries and changes in life expectancy from 1950 to 2010. After applying a measure known as the Biological State Index to the data, they found that the rapid increase in Type 1 diabetes over the last few decades was directly linked with increases in human life expectancy, especially in Western countries—and therefore a reduction in natural selection.
“Up to the early 20th century, Type 1 diabetes was a horrible and dangerous disease, usually leading to people’s deaths during their teens or early 20s,” said lead author, PhD student Mr. You Wenpeng from the University of Adelaide.
This meant there was limited opportunity for people with the disease to have children and pass on their genetic material to future generations, according to You. In evolutionary terms, this is called ‘natural selection.’
“However, with the widespread introduction of insulin from the 1920s onwards, and improvements in modern medicine, life expectancy for people with Type 1 diabetes has now increased to about 69 years,” You said.
“That is a remarkable achievement, but it also means that with reduced natural selection, the genetic material leading to the development of Type 1 diabetes may be accumulating at a rapid rate within the world’s population.”
The researchers decided to investigate the link because although cases of Type 1 diabetes have been increasing globally, its prevalence is uneven in different parts of the world.
According to You, not every country has access to good health care—or, for that matter, freely available insulin. In a number of poor countries such as Africa, the life expectancy for people with Type 1 diabetes is much lower than in the Western world. This means more people are dying prematurely, with less opportunity to produce offspring who will carry those genes from generation to generation.
“Natural selection is one of the major evolutionary forces that inform changes in our genes, across populations and over generations,” said project supervisor and co-author Professor Maciej Henneberg.
“This is the first major disease we have shown that is accumulating due to a relaxation of natural selection over time. It’s unlikely this situation will ever be reversed, meaning that in order to overcome the problems associated with Type 1 diabetes for our population, some form of gene therapy to repair the faulty genes may need to be considered.”
The article can be found at: You and Henneberg (2016) Type 1 Diabetes Prevalence Increasing Globally and Regionally: the Role of Natural Selection and Life Expectancy at Birth.
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Source: The University of Adelaide; Photo: Shutterstock.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.
