Research shows that a high BMI is also associated with type 1 diabetes, not just type 2.

New research published in Diabetology and presented at the annual meeting of the American Diabetes Association in New Orleans, Louisiana, USA, shows that an excessively high body mass index (BMI) in adolescents is associated with the development of type 1 diabetes (the form of the condition that is more associated with autoimmune disease). complications), not just the type 2 form commonly associated with being overweight. The study was conducted by Professor Gilad Twig, Sheba Medical Center, Israel and colleagues.

Type 1 diabetes is traditionally referred to as childhood diabetes and affects children of any age and weight, although it can also develop in adolescence and well into adulthood. However, the rapidly increasing diabetes epidemic growth in almost all countries today consists mainly of cases of type 2 diabetes, linked to risk factors such as: obesity†overweightlow physical activity and increased sedentary behavior.

More recently, studies in younger children have reported an association between elevated BMI and risk of developing type 1 diabetes, but evidence in late adolescence is limited. This is important as approximately 50% of type 1 diabetes cases develop after late adolescence (from the age of 18). In this new study, the authors analyzed the association between BMI in late adolescence and type 1 diabetes in young adults.

In this nationwide study, all Israeli adolescents, ages 16-19 who underwent a medical evaluation in preparation for mandatory military service between January 1996 and December 2016, were included for analysis unless they had a history of abnormal blood sugar levels. A total of 1.46 million adolescents were included. Data were matched with information on the onset of type 1 diabetes in adults in the Israel National Diabetes Registry. Weight and height were measured at study entry and statistical models were used to calculate any increased risk of type 1 diabetes associated with being overweight or obese.

There were 777 new cases of type 1 diabetes during 15,819,750 person-years of follow-up (mean age at diagnosis 25 years). BMI was found to be associated with incident type 1 diabetes. In a model adjusted for age, gender, and sociodemographic variables, the increased risk of type 1 diabetes increased as BMI increased.

Compared to those adolescents classified as optimal BMI (5^e-49^e BMI percentiles by age and sex according to the US Centers for Diseases Control and Prevention), adolescents with obesity (≥95^e percentile) had a double chance of developing type 1 diabetes, while overweight people (85^e-94^e BMI percentile) had a 54% increased risk of type 1 diabetes. A slightly increased risk (41%) was evident in BMI values ​​of the higher normal range (75^e-84^e BMI percentiles). Across the BMI range, authors reported that every 5 kg/m² the adjusted risk of developing type 1 diabetes increases by 35%.

The authors discuss that there is growing evidence of a link between obesity and several autoimmune diseases. One possible explanation they provide is that the elevated levels of inflammatory adipokines and cytokines associated with obesity reduce self-tolerance by promoting pro-inflammatory processes that lead to diabetes.

They add: “Additional factors linked to obesity may contribute to the development of autoimmunity, including vitamin D deficiency, consumption of a high-fat diet and modulation of the gut microbiota. Given that there is an association in our cohort was between adolescent obesity and type 1 diabetes, even when excluding those with pre-existing autoimmune diseases, 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 against various genetic backgrounds that affect the rate of loss of the insulin-producing beta cells in the pancreas and thereby ultimately result in clinical presentation of diabetes. According to this hypothesis, the increasing demand for insulin makes the beta cells more ‘antigen’ (susceptible to autodestruction), thus accelerating their loss through autoimmune damage.

The authors conclude: “Our findings have public health implications. The prevalence of adolescent obesity is rising at an alarming rate worldwide, with bleak prognosis for the foreseeable future. It is currently estimated that nearly 60% of today’s American youth (age group, 2 -19 years) develop obesity by age 35, most of them in adolescence, with half progressing to severe obesity.The current study projects that approximately 1 in 8 (12.8%) of newly diagnosed cases of type 1 in the study can be attributed to abnormal overweight during adolescence. So, with increasing levels of obesity, especially that of the severe form, we can expect the current annual increase in type 1 cases (which varies between +2% and +4% in most high-income countries) will be even more pronounced.”

“Our study adds to the growing evidence regarding the health risks associated with adolescent obesity. Not only is obesity in adolescents correlated with the onset of type 2 diabetes in adults, as previously reported, but also with type 1 diabetes.” More work needs to be done to unravel this association so we can better address the full spectrum of risks from the obesity epidemic or identify common environmental factors that affect both weight and type 1 diabetes mellitus†