Type 1 diabetes (T1D), previously known as juvenile diabetes, accounts for just 5% of diabetes cases, but it is considered more severe because it is usually diagnosed in children and young adults. It is a chronic condition in which the pancreas produces little or no insulin, a hormone needed to allow sugar (glucose) to enter cells to produce energy.

People with T1D require lifelong insulin therapy. The far more common type 2 diabetes occurs when the body becomes resistant to or doesn't make enough insulin.

Now it appears possible that type 1 diabetes might be preventable, simply by making sure that babies and young children have a healthy mix of microbes in their digestive tracts.

A new joint study from MIT, Harvard, Massachusetts General Hospital and the DIABIMMUNE study group have noted a connection between T1D and the microbes living in our guts, the collection of which is referred to as the human microbiome.

When researchers looked at infants who were predisposed to develop T1D, they observed a striking reduction in microbial diversity — especially in those microbes considered to promote gut health — among the children who went on to develop the disease.

The findings could pave the way for diagnostic and therapeutic advances in the treatment of T1D, a disease which is increasing in children.

If the microbial changes that precede the development of diabetes can be detected early, it may be possible to counteract these changes with probiotics and delay or prevent the disease's progression.

Like any other ecosystem, the human microbiome consists of a balance of different organisms that coexist within a common environment. Changes in this balance have been linked to several health conditions, including inflammatory bowel disease and type 2 diabetes.

Breastfeeding appears to help promote diversity in infants' gut bacteria.

The scientists found that among children who went on to develop diabetes, microbiome diversity dropped by 25% one year prior to the onset of T1D. This shift in the balance of microbes included a reduction in those considered to be beneficial and an increase in those known to cause inflammation within the gut.

While previous studies have linked microbiome diversity to T1D, this is the first study to show specific changes that occur before an individual develops the disease.

Since many of the children in the study sample did not develop T1D, the researchers were also able to gather information on how healthy microbiomes develop. They analyzed both the composition of different microbes and the functions that those microbes served.

The team determined that while there was microbial variation from one individual to the next, the composition and function of the microbiomes of healthy infants remained stable over time.

By understanding how microbiome development is related to health from a very young age, researchers hope to one day design diagnostic or therapeutic interventions for T1D. If the microbial changes that precede the onset of diabetes can be detected early, it may be possible to counteract these changes with probiotics and delay or prevent the disease's progression.

The findings are published in Cell, Host & Microbe.