It is often easy to think that diabetes patients must be obese to suffer or have a high mortality rate. This is because it is common knowledge that the more weight one has, the more difficult it is to manage blood sugar and the greater the risk of various complications.
However, contrary to this common belief, a large domestic study has found that underweight type 2 diabetes patients have a higher risk of death than obese diabetes patients. In particular, the mortality rate for underweight patients was found to be as much as 5.2 times higher than that of obese patients.
A joint research team led by Professors Hong Eun-kyung and Choi Hoon-ji from Hallym University Dongtan Sacred Heart Hospital, along with Professor Moon Seon-jun from Gangbuk Samsung Hospital and Professor Han Kyung-do from Soongsil University, recently published these findings in the prestigious international journal 《Journal of Cachexia, Sarcopenia and Muscle》.
The research team utilized big data from the National Health Insurance Service to track 1,788,996 type 2 diabetes patients aged 40 and older who underwent health screenings from 2015 to 2016 until 2022. The analysis was conducted by subdividing the entire population into 8 categories based on body mass index (BMI), ranging from severe underweight (BMI less than 16.0) to severe obesity (BMI 35.0 and above), and then comparing the mortality risk for each group.
As a result, after adjusting for all variables, when the mortality risk of the mild obesity group (BMI 25.0–29.9) was set at 1, the mortality risk for severe underweight (BMI less than 16.0) patients reached 5.2 times.
The mortality risk for moderate underweight (BMI 16.0–16.9) was 3.6 times, and for mild underweight (BMI 17.0–18.4) it was 2.7 times. This indicates that all underweight groups had a significantly higher mortality risk than the severe obesity group (mortality risk 1.5 times). Additionally, the underweight group had mortality rates from diabetes itself, as well as from cardiovascular diseases and cerebrovascular diseases, that were 1.9 to as much as 5.1 times higher than those of the normal and obese groups.
In particular, the risk of being underweight was even more fatal for younger patients. The mortality risk for underweight patients under 65 years old was 6.2, which is 1.84 times higher than that of those aged 65 and older (3.4), indicating that underweight is more fatal for younger diabetes patients.
Type 2 diabetes is the most common type of diabetes, and as weight increases, managing blood sugar becomes more difficult and the risk of complications increases. Because of this, there is a widespread perception that weight loss is essential for diabetes patients. However, this study is significant in that it has demonstrated the risks of being underweight in Asian populations, where the prevalence of 'thin diabetes' is higher compared to Western populations.
The research team pointed to malnutrition and muscle deficiency among underweight patients as the reasons for these results. Professor Hong Eun-kyung, who led the study, stated, "Underweight diabetes patients are likely to be in a state of relative malnutrition or muscle loss, which can negatively impact their survival rate," and recommended, "Instead of excessive weight loss for blood sugar management, it is important to maintain a harmonious overall nutritional status and focus on balanced body composition management."
Professor Hong emphasized, "This study's results demonstrate the need to reassess the BMI criteria for type 2 diabetes patients in Asians not just from the perspective of preventing obesity but from the viewpoint of minimizing mortality risk," and added, "Diabetes patients should shift their focus from merely lowering weight to maintaining an appropriate nutritional status and muscle mass."
