Type 1 Diabetes ‘Boom’: A Case of Reduced Natural Selection?

The increasing prevalence of type 1 diabetes worldwide may be related to reduced natural selection, which is likely associated with advances in medical care, according to data published BMJ Open Diabetes Research & Care.

“Up to the early 20th century, type 1 diabetes was a horrible and dangerous disease, usually leading to people’s death during their teens or early 20s,” lead author Wen-Peng You, a PhD student in University of Adelaide School of Medicine in Australia, said in a press release.

“This meant there was limited opportunity for people with the disease to have children and to pass their genetic material onto future generations. In evolutionary terms, this is what we call ‘natural selection.’”

You also noted that the advent of new medicines and technologies has perhaps interfered with this process.

“… [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 noted in the release.

“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.”

You and Maciej Henneberg, PhD, also from the University of Adelaide and the Institute of Evolutionary Medicine at the University of Zurich in Switzerland, evaluated the prevalence of type 1 diabetes in 118 countries and changes in life expectancy from 1950 to 2010 and used the Biological State Index to determine if a relationship between prevalence of type 1 diabetes and reduced natural selection exists.

Results linked prevalence of type 1 diabetes worldwide to both Biological State Index and life expectancy at birth. Prevalence, however, did not correlate with longevity increase, which was measured as life expectancy at age 50 years.

Partial correlation analysis showed that prevalence of type 1 diabetes was significantly associated with Biological State Index and newborn life expectancy, even after controlling for per capita total sugars availability, per capita gross domestic product (GDP), urbanization, and obesity prevalence, the researchers reported.

Globally, both life expectancy at birth and Biological State Index exponentially correlated with prevalence of type 1 diabetes after the researchers removed 2 outliers of extremely high type 1 diabetes prevalence in Finland and Sweden, according to the data.