The University Hospital

New Insight into Prediabetes: Blood Sugar Level Is More Important Than Body Weight

Analysis shows that a normalized blood sugar level is possible even without losing weight

Until now, weight reduction has been the primary therapeutic goal for people with prediabetes. An analysis of a large Tübingen study shows that patients who bring their blood sugar levels back within the normal range through a healthy lifestyle but do not lose weight, or even gain weight, still reduce their risk of type 2 diabetes by 71 percent. Researchers from the University Hospital of Tübingen, Helmholtz Munich, and the German Center for Diabetes Research (DZD) were involved in the study.

Millions of people worldwide live with prediabetes. It is estimated that one in ten adults is affected, although the number of unreported cases means the real figure is significantly higher. Prediabetes is a condition in which blood sugar values are elevated but do not yet meet the criteria for diabetes. It often remains undetected for a long time, as affected individuals initially have no symptoms. The body’s cells become more resistant to endogenous insulin hormone. As a result, less sugar moves from the blood into the body cells and the blood sugar level increases. The risks are considerable: If left untreated, there is a high risk of developing type 2 diabetes later on—a disease that affects more than 460 million people worldwide. It can lead to serious complications, such as cardiovascular disease or cancer. 

Normal Blood Sugar Level as a Milestone

Strategies recommended to date—including in current guidelines—for the prevention of type 2 diabetes in people with prediabetes primarily focus on reducing weight through a healthy diet and increased physical activity. This strategy, which is limited to weight alone, could be broadened on the basis of the new analysis results. 

A long-term study conducted by the Department of Diabetology, Endocrinology and Nephrology at the University Hospital Tübingen showed that 234 of the more than 1100 study participants lost no weight or even gained weight over the course of a year despite undergoing lifestyle changes. Nevertheless, a good 22 percent of them normalized their blood sugar levels. The development of type 2 diabetes was monitored over a period of up to a further 9 years. Without weight loss, this group was up to 71 percent less likely to develop diabetes. This figure is almost identical to that of individuals who were able to reduce their risk of type 2 diabetes by losing weight (73 percent).

Fat Distribution as a Decisive Factor

The analysis paid particular attention to fat distribution. The relationship between visceral fat (the inner abdominal fat surrounding the organs) and subcutaneous fat (the fatty tissue located directly under the skin) was examined. Visceral fat releases signaling molecules that promote inflammation and disrupt hormone balance, which leads to insulin resistance and is thus directly linked to type 2 diabetes. Study participants whose blood sugar levels returned to normal without losing weight had a lower percentage of abdominal fat as a result of lifestyle changes compared to those whose blood sugar levels remained in the prediabetes range.   

Body Weight No Longer the Sole Indicator

“Restoring a normal fasting blood sugar level is the most important goal in preventing type 2 diabetes and not necessarily the number on the scale,” says Prof. Dr. Andreas Birkenfeld, study leader and director of the Institute for Diabetes Research and Metabolic Diseases (IDM) of Helmholtz Munich at the University of Tübingen. “Exercise and a balanced diet have a positive effect on blood sugar levels, regardless of whether weight is reduced. Losing weight remains helpful, but our data suggests that it is not essential for protection against diabetes,” he continues. “In future, guidelines for the prevention and treatment of type 2 diabetes should not only take weight into account, but above all blood glucose control and fat distribution patterns,” adds Prof. Dr. Reiner Jumpertz-von Schwartzenberg, who, as last author, was involved in the study alongside Prof. Dr. Birkenfeld.

A Healthy Lifestyle as a Recipe for Success

However, the study results highlight the importance of including target glycemic values, i.e., guideline blood sugar values, in practice guidelines in addition to weight reduction targets. Prediabetes remission is the most effective way to prevent future type 2 diabetes, and the analysis suggests that this is partly independent of weight loss. Nevertheless, sufficient physical activity and a balanced diet remain the key means to bring blood sugar values within a normal range.

Title of publication: Prevention of type 2 diabetes through prediabetes remission without weight loss

DOI: 10.1038/s41591-025-03944-9