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New study finds that type 2 diabetics with lower BMI have higher mortality rate

Published: 06 Jan. 2026, 13:56

A blood sugar level measurement device for diabetic patients [KIM HYUN-DONG]

It turns out that losing weight might not be the answer to diabetes. Underweight patients with type 2 diabetes face a significantly higher risk of death than those who are obese, with mortality up to five times higher in the most severe cases, according to a large-scale Korean study.

The study, titled “Underweight and Mortality in Type 2 Diabetes: A Nationwide Retrospective Cohort Study,” analyzed National Health Insurance Service data on 1,788,996 Koreans aged 40 or older diagnosed with type 2 diabetes, tracking them via their health checkups from 2015 through 2022.

The study was conducted by four professors: Hong Eun-gyoung and Choe Hun-jee of Hallym University Dongtan Sacred Heart Hospital, Moon Sun-joon of Kangbuk Samsung Hospital and Han Kyong-do of Soongsil University.

Participants were categorized into eight groups based on their body mass index (BMI), ranging from severely underweight to severely obese. The study found that underweight patients risked death 3.8 times more than those in higher BMI categories. That mortality risk increased as BMI decreased, with it being 5.2 times higher for patients with a BMI under 16 compared to participants with mild obesity.

The underweight group also had a higher mortality risk in relation to diabetes and cardiovascular diseases, with rates 1.9 to 5.1 times greater than those of nonunderweight groups.

Mortality risk was 1.8 times higher for underweight patients under age 65 than for those over 65.

Even after adjusting for variables such as age, sex and income, the mortality risk of underweight patients remained significant, as they were more likely to be older, smoke, exercise less regularly and have lower income.

An illustration of the so-called lean diabetic patient common in Asia [JOONGANG ILBO]

These findings challenge the conventional focus on weight loss in diabetes care, especially for Asian populations for which "lean diabetes” is more common.

“Underweight diabetic patients are often malnourished or have low muscle mass, which can reduce their survival rate,” said Prof. Hong. “Instead of focusing solely on losing weight, it’s critical to maintain proper nutrition and balanced body composition.”

The study was published in the latest issue of the Journal of Cachexia, Sarcopenia and Muscle.

This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
BY JEONG JONG-HOON [[email protected]]