Published 28th September 2026
Diabetes and the gut microbiome: New ZOE research
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Type 2 diabetes is a serious public health concern. In the United Kingdom, it affects around 6 million people (almost 1 in 12 people). And in the United States, that figure is 37.3 million people (around 1 in 10).
Linked to an increased risk of heart disease and premature death, scientists are keen to understand who is most at risk, how to catch it earlier, and how best to treat it.
With these questions in mind, scientists have turned their attention to the microbiome, identifying links between gut bacteria and type 2 diabetes. However, the details of this relationship remain hazy.
A new study by ZOE scientists and colleagues from the University of Trento reopens the investigation, aiming to bring a little more clarity.
The research team identified hundreds of microbes associated with type 2 diabetes. And, importantly, differences in the gut microbiome could be seen before the onset of type 2 diabetes.
According to Prof. Tim Spector, ZOE’s Scientific Co-Founder, they “represent a major step forward in understanding how our gut microbiome is linked directly with metabolic disease."
"Identifying these clear microbial changes long before blood sugar rises or a standard fasting test means earlier intervention with personalized food and lifestyle choices, as well as treatment options, can help to prevent type 2 diabetes.”
Our results were presented at the annual meeting of the European Association for the Study of Diabetes in Milan, Italy (Sept 28 – Oct 2).
What is type 2 diabetes?
When we eat foods that contain digestible carbs, our digestive system breaks them down into glucose, which crosses the intestinal wall and enters our bloodstream.
It then travels around our body to be used as energy.
As with so much in human biology, health is about balance. If blood glucose levels are too low for too long, our body is left without adequate energy, and we’ll die. But if levels are too high for too long, it can also be fatal.
To manage this tightrope walk, the hormone insulin is released when blood glucose levels rise.
Insulin helps muscles and other tissues take up glucose into their cells, helping keep blood glucose levels stable.
People with type 2 diabetes either can’t produce enough insulin, or the insulin they do produce doesn’t work efficiently enough (insulin resistance).
This means that blood sugar levels can quickly become too high, increasing the risk of heart disease and death.
What is prediabetes?
Prediabetes describes someone who has elevated blood glucose levels, but their levels are not yet high enough to be considered diabetes.
These individuals are at an increased risk of developing type 2 diabetes if they don’t make lifestyle changes.
Type 2 diabetes and the gut microbiome
Over the last couple of decades, researchers have found associations between many chronic conditions and the gut microbiome; type 2 diabetes is no different.
Early studies have shown that the gut microbiome of people with type 2 diabetes is measurably different from that of those without the condition.
Scientists hope that understanding how the gut microbiome changes before type 2 diabetes occurs might provide a window of opportunity to intervene before the condition develops and becomes much more difficult to reverse.
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They also want to discover whether modulating the gut microbiome with dietary changes could reduce the risk of developing type 2 diabetes or perhaps even help treat it.
However, many of the studies to date have been conducted on relatively small groups of people, and the species-level differences often varied across studies, making it hard to draw conclusions.
Another challenge is that diabetes medications, such as metformin, can themselves influence the makeup of the gut microbiome.
This makes it difficult to pinpoint what differences are due to the medication and which are related to type 2 diabetes.
ZOE’s scientists decided to take a fresh look at these questions. Thanks to our members, we have a huge dataset, making this recent study the largest of its type to investigate the relationship.
What did we do?
ZOE’s scientists and colleagues used data from 229,025 individuals from the UK and the US who are part of our ZOE PREDICT 3 study. Of these individuals, 3,687 had type 2 diabetes, and 14,022 had prediabetes.
Each participant provided a stool sample and other important information, including which medications they were taking, their BMI, age, sex, and family history of diabetes.
This information allowed us to compare the gut microbiomes of people with type 2 diabetes, prediabetes, and healthy glucose control.
What did we find?
These are some of the most important findings from the analysis:
Almost 800 gut bacteria species were associated with type 2 diabetes: 168 were more abundant, and 621 were less abundant than in people without diabetes.
Of the 800 species, almost 600 were also associated with prediabetes.
And more than 500 of the species were found in people with healthy blood glucose control but who had a family history of type 2 diabetes, and were therefore at an increased risk.
The researchers also found that diabetes-related differences in the gut microbiome were present among those taking metformin and those who were not taking it. However, the differences were larger among those taking medication.
This might be because metformin amplified the gut microbiome changes associated with type 2 diabetes, or because people with untreated diabetes have, on average, less severe diabetes.
Also, the scientists showed that the measurable differences in gut microbes were not dependent on age, sex, BMI, or geographical location.
In other words, the type 2 diabetes-related differences were independent of other factors known to be associated with changes in the microbiome.
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Why does it matter?
In this study, the scientists found measurable differences in the gut microbiome “along the continuum of insulin resistance.” So, even before type 2 diabetes develops, differences in the gut microbiome could be measured.
This means that the gut microbiome could one day be a useful way to identify who is at greatest risk of developing type 2 diabetes.
This would allow doctors to intervene with lifestyle advice earlier, potentially preventing the onset.
If further work confirms associations between individual bacterial species and type 2 diabetes, we may also be able to design dietary interventions that specifically target diabetes-associated gut microbes.
Although there’s a long road ahead, this study could help pave the way for potentially life-saving diabetes interventions.
