Study investigates how natural selection and medical advances affect type 1 diabetes rates

The global increase in type 1 diabetes rates is directly linked to advances in medical care which are helping people live longer, according to scientists from the University of Adelaide.
The Adelaide team, led by Dr Wenpeng You, also reported that the underlying genetics of type 1 diabetes makes it more likely to be passed from one generation to the next.
The researchers used a measure called the Biological State Index to find that increased worldwide rates were directly linked with increases in human life expectancy, particularly in Western countries.
You explained that up until the early 20th century, people with type 1 diabetes would most commonly die during their teens or early 20s. As a result, they had a limited opportunity to pass on their genetic material to future generations. This is what is known as natural selection.
“[Due to] improvements in modern medicine, life expectancy for people with type 1 diabetes has now increased to about 69 years,” said You, and this means that there is a reduction in natural selection.
Instead, “the genetic material leading to the development of type 1 diabetes may be accumulating at a rapid rate within the world’s population.”
The global prevalence of type 1 diabetes remains uneven in different parts of the world, though. “Not every country has access to good health care, or freely available insulin. In a number of poor countries, such as in African, the life expectancy for people with type 1 diabetes is much lower than in the Western world,” said You.
“This means more people are dying prematurely, with less opportunity to produce offspring who will carry those genes from generation to generation.”
The researchers have called for a type 1 diabetes epidemiology study in total populations to identify the causes of increasing type 1 diabetes.
The findings appear in BMJ Open Diabetes Research and Care.