Exploring the TyG Index and the Homeostasis Model Assessment of Insulin Resistance As Insulin Resistance Markers: Implications for Fibromyalgia Management and Understanding-A Narrative Review

Fibromyalgia (FM) is a chronic musculoskeletal disease with a higher prevalence among women. To date, there has been no definitive laboratory or imaging assessment for FM, and hence, the diagnosis criteria for FM remained based on subjective assessment of symptoms with high overlap with other rheumatological disorders. Many patients with FM suffer from metabolic disorders leading to insulin resistance (IR). There have been several methods to assess IR, among which the Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) and the triglyceride-glucose (TyG) index have been used more frequently, with the latter being more available and cost-effective. As higher IR has been reported for patients with FM with various mechanisms, in this review, we sought to investigate the association between IR and FM using the current evidence. One of the possible underlying mechanisms of this association might be mitochondrial dysfunction and oxidative stress observed in IR conditions and its role in FM. Studies have also shown that IR indices are higher in patients with FM, compared to healthy controls, while higher HOMA-IR levels were also reported for higher severities of FM based on Fibromyalgia Impact Questionnaire-Revised (FIQR) scores. While these findings suggest the possible involvement of IR in FM pathophysiology and add to the value of IR measurement in FM clinical assessment, further large-scale studies are needed to establish a definitive causal association between them.