For years, people with prediabetes have been told that losing weight is the best way to lower their risk of type 2 diabetes.
But new research from Germany suggests that keeping blood sugar levels within a healthy range may be even more important than the number on the scale.
The study, published in Nature Medicine and led by scientists at the University Hospital of Tübingen, Helmholtz Munich, and the German Center for Diabetes Research, shows that people who manage to normalize their blood sugar levels—even if they don’t lose weight—cut their risk of developing type 2 diabetes by more than 70%.
Prediabetes affects an estimated one in ten adults worldwide, though the real number is likely higher since the condition often goes unnoticed.
In prediabetes, blood sugar levels are above normal but not yet high enough to be classified as diabetes.
The condition happens when the body becomes resistant to insulin, the hormone that helps move sugar out of the blood and into cells for energy.
Over time, this resistance pushes blood sugar levels higher, greatly increasing the risk of developing type 2 diabetes.
Type 2 diabetes is one of the world’s most common chronic diseases, affecting more than 460 million people.
It can lead to serious complications, including heart disease, stroke, and even certain cancers. Preventing the disease in people with prediabetes is therefore a major public health goal.
Until now, most prevention guidelines have focused on weight loss through healthy eating and exercise. But the new Tübingen study suggests this approach may be too narrow.
The researchers followed more than 1,100 people with prediabetes over several years.
After one year of lifestyle changes—such as eating a healthier diet and being more physically active—about 22% of participants who had not lost weight, or had even gained some, managed to bring their blood sugar levels back into the normal range.
When researchers tracked these participants for up to nine more years, they found that this group was 71% less likely to develop type 2 diabetes compared with those who did not achieve normal blood sugar. Strikingly, this reduction in risk was nearly identical to that seen in participants who lost weight (73%).
One key difference, however, was in fat distribution.
People who normalized their blood sugar without losing weight tended to have less visceral fat—the deep fat around abdominal organs that is strongly linked to insulin resistance—than those who remained in the prediabetes range.
Unlike the fat that lies just beneath the skin, visceral fat is biologically active, releasing substances that drive inflammation and disrupt hormone balance.
According to Professor Andreas Birkenfeld, who led the study, the findings should reshape how doctors think about diabetes prevention.
“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,” he said. Exercise and balanced eating help regulate blood sugar, even if weight stays the same.
Losing weight can still help, but it is not the only path to protection. The researchers argue that future diabetes guidelines should focus more on blood sugar control and fat distribution rather than weight alone.
For people living with prediabetes, the message is clear: healthy lifestyle habits remain the foundation of prevention, but the main milestone to aim for is normal blood sugar levels, not necessarily dramatic weight loss.
