Every health care professional sees patients who don’t fit a diagnostic mold, and diabetes is no exception. While the majority of people with diabetes have a diagnosis of type 1 or type 2 diabetes, others do not have a medical history or signs consistent with these diagnoses. NIDDK hopes to shed light on these unusual forms of the disease in a new study called the Rare and Atypical Diabetes Network, or RADIANT.

Launched in September 2020, the nationwide study will gather detailed health information about participants to help researchers identify and describe unusual forms of diabetes, develop better diagnostic methods, and investigate their causes, which may eventually lead to new treatments —ultimately improving patients’ quality of life. Researchers for RADIANT plan to screen about 2,000 adults and children and conduct more in-depth studies in about 800 of them.

People with atypical diabetes often are not diagnosed correctly and don’t get proper treatment, according to the RADIANT website. They include, for example, patients who are diagnosed with type 2 diabetes before the onset of puberty and those who do not have typical type 2 diabetes risk factors, such as being overweight or having abnormal cholesterol levels and high blood pressure. The atypical group also includes people who are diagnosed with type 1 diabetes but do not have detectable levels of diabetes autoantibodies, which are usually found in type 1 diabetes. Other examples include people diagnosed with diabetes who respond in unexpected ways to standard treatments, have an atypical disease course, or have other unusual systemic disorders.

“In general, we are looking for new forms of diabetes,” said RADIANT project scientist Christine Lee, MD, program director in the NIDDK’s Division of Diabetes, Endocrinology, and Metabolic Diseases. “Any patient who does not fit the typical picture of type 1 or type 2 diabetes can be referred to the study.” The RADIANT website details characteristics and symptoms of possible participants (see “Who Can Join RADIANT?”).

Potential participants can be screened on the RADIANT website, with questions about personal medical history, medications, and other health information. Those who are eligible will complete additional surveys; provide blood samples for genetic and other testing; and have a comprehensive physical exam. Some family members of enrollees may also be invited to take part. All participants will get their clinical test results.

RADIANT will recruit participants for at least three years at 14 clinical centers. The University of South Florida, Tampa, is the study’s coordinating center. In addition, Baylor College of Medicine, Houston, and the Broad Institute, Cambridge, Massachusetts, serve as genomic sequencing centers that process genetic samples. The central laboratory is located at the University of Florida, Gainesville.

In addition to describing the clinical and genetic characteristics of atypical forms of diabetes, RADIANT researchers hope that their efforts to clarify new diagnoses will inform future studies to determine their prevalence. Dr. Lee said, “Our first step is to identify and characterize these new forms of diabetes. Once we know how best to screen for them, broader studies among people with diabetes or in the general population can be conducted to find out exactly how common or uncommon they are.”

While the study will focus on helping health care professionals and patients understand these rare, unusual forms of diabetes, it may also help scientists and health care professionals broaden their ideas about the spectrum of common forms of diabetes, like type 2 diabetes. “Our patients with type 2 diabetes are all different from each other, and there’s no one size fits all. By studying the extreme differences, we hope to get a better understanding of the similar but less extreme differences that may be present. This may have implications for more tailored approaches to type 2 diabetes,” Lee said.

For researchers, RADIANT will offer access to patient data and samples—some of it through the NIDDK Data Repository—and an opportunity to conduct ancillary studies in partnership with the RADIANT study group. “We want to generate a set of data and biospecimens and make it available to the broader research community in a secure way,” Dr. Lee said.

For more information about RADIANT, read the NIDDK press release. See the RADIANT website for more information for researchers.