New research published in the journal Diabetologia and presented at this year’s annual meeting of the American Diabetes Association suggests adolescents with an excessively high BMI (Body Mass Index) in their late teenage years may be more susceptible to developing type 1 diabetes in early adulthood.

The study was completed by Professor Gilad Twig and team at Sheba Medical Center in Israel.

Type 1 diabetes has been traditionally referred to as childhood diabetes, occurring in children of any age and weight, although it can also develop in adolescence and well into adulthood.

The new study analysed the association between BMI in late adolescence (from age 18 years) and incidence of type 1 diabetes in young adulthood.

In this nationwide study, all Israeli adolescents, ages 16–19 years, undergoing medical evaluation in preparation for mandatory military conscription between January 1996 and December 2016, were included for analysis unless they had a history of abnormal blood sugar. A total of 1.46 million adolescents were included. Data were linked with information about adult onset of type 1 diabetes in the Israeli National Diabetes Registry. Weight and height were measured at study entry, and statistical modelling was used to calculate any excess risk of type 1 diabetes associated with overweight or obesity. In a model adjusted for age, sex and socio-demographic variables, the increased risk of type 1 diabetes increased as BMI increased.

“Given that, in our cohort, there was an association between adolescent obesity and type 1 diabetes even when excluding those with pre-existing autoimmune conditions, additional factors may link obesity specifically to type 1 diabetes.”

They explain that several biological mechanisms have been suggested to explain the association between obesity and type 1 diabetes. The ‘accelerator’ hypothesis suggests that both type 1 and type 2 diabetes are caused by insulin resistance set against various genetic backgrounds that affect the rate of loss of the insulin-producing beta cells in the pancreas and thereby ultimately resulting in clinical presentation of diabetes. According to this hypothesis, the increasing demand for insulin renders the beta cells more ‘antigenic’ (prone to auto-destruction), and thus accelerates their loss through autoimmune injury.

The current study projects that around 1 in 8 (12.8%) of the newly diagnosed cases of type 1 in the study can be attributed to abnormally excessive weight at adolescence.

“Further work needs to be done to unravel this association so that we can better address the full spectrum of risks posed by obesity or identify common environmental factors affecting both weight and type 1 diabetes.”