Overactive Bladder (OAB) is defined by the International Continence Society as a chronic condition with urinary urgency as the main symptom, accompanied by urinary frequency, nocturia and urge incontinence (UUI), excluding clear pathological changes such as urinary tract infection. Epidemiological data show that the prevalence of OAB has been increasing over the past 20 years, with a global prevalence of OAB ranging from approximately 10.7% to 23.9%, and that its incidence increases significantly with age, especially in women over 44 years of age and men over 64 years of age (1). As a urological condition that severely affects quality of life (2), the medical costs of patients with OAB are more than two and a half times higher than those of patients without the condition (3), resulting in a significant burden on their families and social services. As a disease that seriously affects quality of life, the medical costs of OAB patients are more than 2.5 times higher than those of non-OAB patients, placing a heavy burden on their families and social welfare, and has become a major public health problem (4).

The etiology of OAB is thought to be multifactorial, involving neurogenic, myogenic, uroepithelial, or a combination of factors (5). Despite extensive research, the exact pathogenesis of OAB remains poorly understood, and it is possible that chronic inflammation (6) and elevated levels of oxidative stress may play a role in its development (7). Previous studies have shown that components of the metabolic syndrome (MetS), such as obesity, as well as diabetes mellitus, are associated with higher levels of inflammation and oxidative stress and are strongly correlated with OAB (8). IR may cause autonomic dysfunction, suggesting that insulin resistance (IR) may play a key role. IR may cause autonomic dysfunction and may be associated with OAB. Previous studies have shown that components of the metabolic syndrome (MetS), such as obesity and diabetes mellitus, have higher levels of inflammation and oxidative stress and are strongly correlated with OAB, suggesting that insulin resistance (IR) may play a key role. IR may cause autonomic dysfunction, thereby increasing bladder sympathetic tone, and hyperinsulinemia may directly stimulate urethral myocyte proliferation, which together contribute to the development of OAB (9).

Plasma insulin is the main indicator for assessing IR, and insulin levels are affected by a variety of factors, such as diet, exercise, and sleep (10), leading to greater fluctuations in test results, as well as disadvantages such as its high cost of testing and susceptibility to drug interference, and the results measured may not accurately reflect the patient’s IR level (11). The triglyceride-glucose index (TyG index) reflects the metabolic triglyceride and glucose metabolism, and these changes are closely related to IR, which is another new index used to assess IR in recent years. In comparison with the HOMA-IR model, the TyG index is more sensitive for the prediction and diagnosis of disease in the assessment of homeostatic models of IR and is more convenient and accessible in clinical practice (12, 13). Previous studies have shown that an elevated TyG index is strongly associated with a variety of conditions including asthma (14), kidney stones (15) and erectile dysfunction (16) and has demonstrated predictive value for cardiovascular events, atherosclerosis and chronic kidney disease in several large cohort studies (17).Although the association of TyG index with metabolic diseases has been confirmed by extensive studies, there is a gap in direct research on its association with OAB. Based on the above evidence, we explored the association between TyG index and OAB using data from the 2005–2018 U.S. National Health and Nutrition Examination Survey (NHANES), and we hypothesized that a higher TyG index is associated with an increased likelihood of OAB.

In this study, we explored the association between TyG index and OAB for the first time in a large population based on NHANES data. Through multidimensional analysis, we revealed an independent positive association between TyG index as a metabolic marker and the risk of OAB, and the results remained consistent after different stratification and sensitivity analyses.

In the fully adjusted model, there was an 18% increase in risk of OAB for each 1-unit increase in TyG index, and a significant dose-response relationship was observed when grouped into quartiles. The mechanisms underlying the relationship between TyG index and OAB may be independent of traditional metabolic syndrome components and may affect bladder function either directly or through other unmeasured pathways such as microangiopathy. Possible mechanisms include: Elevated TyG index is positively correlated with inflammatory markers such as interleukin-6 (IL-6) and C-reactive protein (CRP), which may contribute to the activation of related pathways to increase afferent neural sensitivity to the bladder (6, 16). At the same time, insulin resistance may lead to mitochondrial dysfunction and urethral (20) muscle fibrosis through oxidative stress injury mechanisms (17). Finally, through an autonomic dysregulation (21) mechanism, a high TyG index may increase sympathetic activity and induce detrusor overactivity (18). Together, these mechanisms contribute to OAB.

Subgroup analysis showed that the association between TyG index and OAB was still robust after adjustment for metabolic comorbidities such as diabetes mellitus and asthma, suggesting that the association between TyG index and OAB was more pronounced in people younger than 60 years and in female patients. Possible mechanisms include: a greater metabolic compensatory capacity in the younger population (22), and the associated inflammatory response due to insulin resistance is more likely to induce early bladder dysfunction (23). Females have higher levels of estrogen than males, and estrogen may enhance sensory afferents to the bladder by regulating TRPV1 channel expression (24). The urothelium of females is more sensitive to metabolic disturbances (8). The TyG index is independently and positively correlated with the risk of OAB, which is more robust in the younger population and in females. The TyG index, as a simple and inexpensive metabolic marker, may be a potential tool for early screening for OAB, especially in individuals with metabolic abnormalities who do not develop significant metabolic disorders. Prioritizing lifestyle interventions to reduce TyG index levels in patients with a high TyG index may be helpful in improving OAB symptoms. However, the clinical application of the TyG index needs to be further validated and its clinical value as a screening tool needs to be supported by further studies.

The present study also has several limitations. First, this study was based on a cross-sectional design, which provided evidence of a positive correlation between the TyG index and OAB. However, a causal relationship between these two variables could not be explained because OAB is a collection of symptoms caused by multiple factors. Although we controlled for some relevant confounders, we could not completely eliminate the effects of other confounding variables. Therefore, our results should be treated with caution. Second, the study data were derived from the US NHANES database and are not representative of the characteristics of the global population. In addition, the diagnosis of OAB is based on questionnaires, which may be subject to recall bias. Therefore, future studies need to validate the findings of this study in different populations and conduct multicenter prospective cohort studies to further clarify the causal relationship between TyG index and OAB.

This study demonstrates for the first time that TyG index is independently and positively associated with the risk of OAB, and that it is more pronounced in the younger age group and in females.TyG index may provide a potential tool for early screening for OAB, especially in individuals with metabolic abnormalities but who have not developed significant metabolic disorders. Further cohort studies are still needed in the future to demonstrate the potential association.