In a recent clinical study, researchers found that muscle ultrasound may serve as a noninvasive, low-cost method for detecting early signs of insulin resistance and reduced muscle mass in patients with obesity as well as for identifying at-risk patients prior to the onset of type 2 diabetes.
The researchers recruited 20 adult patients with obesity, all of whom were free from prediabetes or type 2 diabetes, and five lean individuals serving as healthy controls. They focused on two major muscle groups: the deltoid in the upper arm and the vastus lateralis in the thigh. The researchers captured ultrasound images to calculate muscle echo intensity (MEI)—a measure that reflects how much fat or fibrotic tissue is present in the muscle. A higher MEI value typically signals abnormal tissue composition, which can interfere with insulin action.
MEI values were found to be higher in the participants with obesity compared with the controls. In the vastus lateralis, MEI in the obese group was more than double that of the control group, with similar increases seen in the deltoid.
Sixteen participants with obesity also underwent hyperinsulinemic-euglycemic clamps, the gold standard for evaluating insulin sensitivity. Half met the criteria for insulin resistance, and nearly 44% showed impaired insulin sensitivity. All of the participants with these metabolic impairments also had elevated MEI, suggesting a strong association between ultrasound findings and early metabolic dysfunction.
The study also found that MEI correlated negatively with muscle mass. Using dual-energy x-ray absorptiometry (DEXA), the researchers calculated two muscle health indices: appendicular skeletal muscle index and fat-free mass index. MEI demonstrated a strong inverse correlation with both indices, indicating that higher MEI may reflect early sarcopenia.
Notably, MEI didn't correlate with body mass index (BMI). Some of the participants with similar BMIs had very different MEI values, highlighting ultrasound’s potential to provide more detailed insights into muscle and metabolic health.
Compared with traditional methods, muscle ultrasound offered practical advantages. The clamp procedure is complex and time-consuming, while DEXA and magnetic resonance imaging scans, though effective, are expensive and less accessible. DEXA and computed tomography also involve radiation exposure. Conversely, ultrasound is portable, radiation-free, and suitable for bedside use, including with handheld devices. These features could broaden its application in clinical and community settings.
The researchers noted that further studies with larger samples are needed. They also plan to investigate the biological factors contributing to elevated MEI,csuch as fat infiltration, fibrosis, and inflammation in skeletal muscle, among insulin-resistant patients.
The study added to growing interest in using ultrasound for the early detection of chronic conditions. Identifying insulin resistance and declining muscle mass early could support more timely interventions and help prevent complications related to type 2 diabetes and sarcopenia.
The authors reported no conflicts of interest.