A simple blood sugar test one hour after drinking a glucose solution may help doctors spot early signs of type 2 diabetes—even before prediabetes begins.
That’s the finding from a new study by researchers from the University of Tübingen, Helmholtz Munich, and the German Center for Diabetes Research (DZD), in partnership with Professor Michael Bergman of New York University. The research has been published in the journal Metabolism.
Prediabetes is known as a warning stage before type 2 diabetes. However, not everyone with prediabetes develops diabetes. In fact, more than 40% of people with prediabetes do not go on to get diabetes within 10 years.
Even more concerning, current medical guidelines may miss up to 20% of people who eventually develop diabetes. These people never get an early warning.
To solve this problem, scientists searched for a better marker to detect diabetes risk earlier. They focused on a reading called “1-hour plasma glucose” (1h-PG). This number comes from the oral glucose tolerance test (OGTT), where the patient drinks a sugary solution and has blood sugar checked at several points in time.
A 1h-PG reading of 155 mg/dl or higher could show problems earlier than other measures like fasting sugar or two-hour sugar levels.
To test this idea, the research team ran a lifestyle program in Tübingen, Germany. They followed 317 adults with different levels of blood sugar control for nine months. The goal was to help each person lose at least 5% of their weight through healthy eating and regular exercise.
At the start of the study, people were divided into three groups: those with normal blood sugar, those with only elevated 1-hour glucose levels, and those with prediabetes. People with high 1-hour readings were already showing early warning signs.
Their insulin sensitivity and beta-cell function were worse than healthy people, and they had higher levels of fat in the liver and belly. But these changes were still reversible.
After nine months of lifestyle changes, those in the 1h-PG group had made big improvements. Their insulin function and beta-cell response became as good as those in the healthy group. Their liver fat also dropped back to normal levels. The improvements were much better than in the group with full prediabetes.
When the researchers followed these participants for up to 12 years, they found even more promising results. People who had elevated 1-hour glucose at the start but joined the lifestyle program were 80% less likely to get type 2 diabetes compared to people with prediabetes.
Nearly half of them reached normal blood sugar levels—twice the success rate of the prediabetes group.
The first author of the study, Yiying Wang, said the improvements were likely due to both weight loss and reduced liver fat, which helped the body respond better to insulin and sugar. Fixing these key issues could help people return to a healthy and stable metabolism.
Senior author Professor Andreas Birkenfeld said the 1-hour glucose value turned out to be the best early warning sign. It was more helpful than traditional tests like HbA1c, fasting sugar, or the two-hour reading. He believes that this could become a new tool for doctors to find and help at-risk people before they even have prediabetes.
If widely adopted, the 1-hour blood sugar reading could change how diabetes is prevented. By catching problems earlier, more people could return to normal blood sugar levels—and avoid diabetes altogether.
If you care about diabetes, please read studies about Vitamin D and type 2 diabetes, and to people with diabetes, some fruits are better than others.
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