Teens who are obese face a higher risk of developing type 1 diabetes, a new study from Israeli researchers reports. The study, which was conducted on military recruits, sheds important new light on type 1 diabetes, which has customarily not been associated with overweight and has usually been thought to begin in childhood.
Type 1 diabetes used to be called juvenile diabetes, but the name was changed when researchers began to realize that it can happen at any age. According to Gilad Twig, MD, of the Sheba Medical Center in Israel and one of the study authors, “By reputation, people think it’s a disease of children. But it’s begun to grow so that now 50% of cases occur after late adolescence.” And because type 1 diabetes is rising among adults, speculation that it might be connected to lifestyle factors is also rising.
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Type 1 risk linked to BMI among teens
The researchers collected health data on nearly 1.5 million 17 year olds (58% male, 42% female) who were given medical evaluations before they began Israeli military service in 1996 and then followed their health histories through 2016. At the beginning of the study, none of the subjects showed any abnormalities in blood sugar levels, but over the succeeding years, 777 cases of type 1 diabetes were observed. Then, over a median follow-up of about 11 years, researchers broke down the incidence of type 1 diabetes by different BMIs among the subjects (BMI, or body-mass index is a standard by which overweight and obesity is measured). They found that the higher the BMI among a cohort of subjects, the more likely they were to develop type 1 diabetes. They did this by using “hazard ratios,” which is a way of measuring how often an outcome happens in one group compared to another.
To study any relationship between overweight and type 1 diabetes, the researchers calculated hazard ratios on BMIs in different ranges of the scale. They determined that the hazard ratio for BMIs in the 50th to 74th percentile was 1.05. For the 75th to 84th percentile it was 1.41. For those who were overweight the hazard ratio was 1.54, and for those who were obese it was 2.05. In other words, as BMIs rose, so did the chances of developing type 1 diabetes. To put it another way, the researchers calculated that for every five-unit increase in BMI there was a 35% greater incidence of type 1 diabetes. The idea that little or no relationship exists between type 1 diabetes and overweight was certainly called into question.
The question then became: why? The researchers could only conjecture and in a separate article offered several possibilities. The first has to do with autoimmune conditions. It appears there is a link between elevated levels of two body chemicals — adipokines and cytokines — and inflammation, and inflammation is a contributing factor in diabetes. Another possibility is based on some modest evidence that overweight people have a greater risk of what’s called islet autoantibody expression, a condition that seems to be linked to type 1 diabetes. Other possibilities include vitamin D deficiency, a high-fat diet, and microorganisms in the gastrointestinal system, or gut microbiota.
Finally, there’s what’s called the “accelerator hypothesis,” which theorizes that both type 1 and type 2 diabetes are the same disorder and are fostered by beta cell death (death of the cells that produce insulin), beta cell autoimmunity, and insulin resistance. Because insulin resistance is caused by weight gain, abdominal fat, and an inactive lifestyle, it’s possible that obesity actually might be a contributing factor to type 1 diabetes — in other words, according to this study, lifestyle seems to indeed play a role. As Dr. Twig put it, “For people who might have a high risk for developing type 1 diabetes, these results emphasize the importance of maintaining a normal weight.”
Want to learn more about raising a child with type 1 diabetes? Read “The Type 1 Diabetes Diagnosis,” “Type 1 Diabetes at School: What Personnel Need to Know,” and “Type 1 Diabetes and Sleepovers or Field Trips.”