High echogenicity, or unusual brightness, of the deltoid muscle on ultrasound may be a warning sign of diabetes, according to a study led by musculoskeletal radiologist Steven B. Soliman, DO, of Henry Ford Hospital in Detroit. This research will be presented next week at the annual meeting of the Radiological Society of North America (RSNA).

For the study, researchers compiled 137 shoulder ultrasounds from patients with type 2 diabetes, including 13 with pre-diabetes. The researchers also obtained 49 ultrasounds from obese patients without diabetes.

The researchers showed the ultrasounds to two musculoskeletal radiologists who were unaware of patients’ diabetes status .The radiologists  classified the patients, based on the brightness of their shoulder muscle, into one of three categories: normal, suspected diabetes and definite diabetes. A third musculoskeletal radiologist acted as an arbitrator in the cases where the other two radiologists disagreed.

The results revealed that by using the echogenicity of the deltoid muscle, radiologists were able to correctly predict diabetes in 70 of 79 patients, or 89%. Brightness on ultrasound also was an accurate predictor of pre-diabetes, a condition of abnormally high blood sugar that generally progresses to diabetes without changes in lifestyle.

The findings could allow for earlier interventions. “If we observe this in patients with pre-diabetes and diabetes, we can get them to exercise, make diet modifications and lose weight,” Soliman says. “If these interventions happen early enough, the patients may be able to avoid going on medications and dealing with all the complications that go with the disease.”The reasons for the brighter-appearing shoulder muscle on ultrasound among patients with diabetes is not completely understood, but may be due to low levels of glycogen in the muscle, a key source of energy for the body that is stored primarily in the liver and muscles.

The researchers plan to continue studying the connection between shoulder muscle echogenicity and diabetes with an eye toward quantifying the phenomenon and seeing if it is reversible.