In the largest longitudinal study of the microbiome to date:

Researchers from the Broad Institute of MIT and Harvard, Massachusetts General Hospital (MGH), and the DIABIMMUNE Study Group have identified a connection between changes in gut microbiota and the onset of type 1 diabetes (T1D). The study, which followed infants who were genetically predisposed to the condition, found that onset for those who developed the disease was preceded by a drop in microbial diversity -- including a disproportional decrease in the number of species known to promote health in the gut. These findings, published by Cell, Host & Microbe, could help pave the way for microbial-based diagnostic and therapeutic options for those with T1D.

The human microbiome, which consists of the trillions of microorganisms (bacteria, viruses, and other assorted "bugs") that reside in our bodies, has become an area of growing interest to the medical community as researchers have begun to probe the role it plays in human health and disease. While most bugs in our microbiome are harmless, and even beneficial, changes in the microbiome (and in the interactions microbial species share with their human hosts) have been linked to various disease states, including diabetes and Inflammatory Bowel Disease (IBD).