Ultrasound of Key Muscles May Predict Insulin Resistance Before Diabetes Onset

A simple ultrasound scan of specific muscles could serve as an early indicator of insulin resistance, potentially identifying the condition before it develops into diabetes.

Researchers at Michigan Medicine recently explored the effectiveness of using muscle echo intensity measurements—specifically of the deltoid and vastus lateralis muscles—to detect insulin resistance. According to their findings, the approach was “100% accurate” in identifying insulin sensitivity, even when standard blood markers were absent.

The research was inspired by clinical observations made by musculoskeletal specialists at Michigan Medicine, who began noticing a recurring trend in their patient population.

“We perform a large number of shoulder ultrasounds and noticed that many patients' muscles appear unusually bright,” said lead author Steve Soliman, DO, director of musculoskeletal ultrasound and the MSK radiology fellowship at the University of Michigan, in a news release. “We found it interesting that most of these patients have type 2 diabetes. Seeing this pattern, we often thought, 'This patient must have diabetes.' More importantly, many were unaware of their condition until we verified with their electronic records and confirmed with their bloodwork that they indeed had type 2 diabetes or prediabetes.”

To test this hypothesis, Soliman and his team conducted ultrasound evaluations on 25 participants with varying medical backgrounds. The study included 20 individuals with obesity but no diabetes diagnosis and five healthy controls. Ultrasound imaging was performed on the shoulder region.

Two independent reviewers, who had no knowledge of the patients' health status or demographics, assessed the ultrasound images and measured muscle echo intensity. These readings were then compared against peripheral insulin sensitivity metrics. In addition, dual-energy x-ray absorptiometry was used to analyze body composition and calculate sarcopenia indices.

The results revealed that patients in the obese group showed notably elevated muscle echo intensity in both the deltoid and vastus lateralis muscles. These higher values strongly correlated with insulin resistance and reduced insulin sensitivity. The researchers also identified a negative correlation between muscle echo intensity and muscle mass, overall body weight, and obesity, indicating that this method can effectively distinguish insulin resistance from other variables.

This increased muscle brightness on ultrasound is believed to represent abnormal fat deposits and potential fibrosis, both of which can harm muscle health and performance.

Notably, these ultrasound findings were observed before any abnormal blood glucose levels—such as elevated HbA1C—were detected, suggesting that high muscle echo intensity might be an early biomarker for prediabetes and diabetes.

Though limited by a small sample size, the researchers are optimistic that these insights could lead to broader use of ultrasound in primary care settings, allowing for earlier detection of insulin resistance.

“Clinicians increasingly use these point-of-care and handheld ultrasound devices, sometimes called ‘the stethoscope of the future,’ for rapid diagnosis of various conditions,” Soliman said. “This information could be automatically analyzed by these noninvasive devices. A medical assistant or clinician with little to no training could easily use this device on a patient’s upper arm or thigh, as routinely as checking weight or blood pressure, and potentially flag patients as 'high risk' or 'low risk' for further testing.”