Losing weight can help lower the risk of type 2 diabetes, but new research suggests the benefits may not be the same for everyone.
In a long-term observational study published in Diabetes, researchers found that one group of adults at elevated risk for type 2 diabetes continued to have rising blood sugar, declining insulin secretion and a persistently high diabetes risk despite losing a substantial amount of weight and keeping it off for years.
The study looked at participants in the Tübingen Lifestyle Intervention Program, a two-year lifestyle program for people at increased risk of type 2 diabetes. Researchers then followed participants for about nine years, focusing on those who achieved substantial and sustained long-term weight loss.
The key finding was not that lifestyle changes do not matter. Rather, it was that some people may have underlying metabolic patterns that make standard diabetes prevention strategies less effective.
Researchers wanted to know whether certain high-risk groups responded differently to long-term weight loss.
“We were very surprised to find that, despite a large and sustained weight loss of 8% ... individuals in risk cluster 5 showed increasing blood glucose levels ... and a persistently high risk of type 2 diabetes,” said lead author Professor Norbert Stefan.
That risk cluster was linked to insulin resistance and fatty liver disease. Researchers said these factors may help explain why blood sugar continued to worsen even after long-term weight loss.
The study adds nuance to a familiar public health message. Healthy eating, physical activity and weight management remain important tools for reducing diabetes risk. But the findings suggest body weight alone may not capture the full picture of metabolic health.
That distinction matters because two people can lose similar amounts of weight but have different changes in blood sugar, insulin function and liver health. For someone with prediabetes, fatty liver disease, a strong family history of type 2 diabetes or worsening blood sugar despite weight loss, this research points to the importance of looking beyond the scale.
The study does not prove that fatty liver disease caused diabetes risk to remain high. It also does not show that lifestyle changes are ineffective. Because the research was observational, it can identify patterns and possible explanations, but it cannot prove cause and effect.
The authors said the findings need to be confirmed in prospective studies. If they are, diabetes prevention may need to become more personalized, with higher-risk groups receiving more intensive or targeted support.
The Tübingen Lifestyle Intervention Program was supported by a grant from the Deutsche Forschungsgemeinschaft. The current study was supported by a grant from the German Federal Ministry of Education and Research to the German Centre for Diabetes Research.