Hypertension, characterized by consistently elevated blood pressure (BP) levels, stands as a primary risk factor for cardiovascular disease (CVD) and mortality in middle-aged and older adult individuals (1, 2). A nationwide survey conducted in China in 2012 revealed that approximately 23.2% of adults were afflicted with hypertension (3), with estimates suggesting this prevalence could reach up to half among individuals aged 35–75 years (4). The aging demographic has witnessed a notable surge in cases of hypertension, with projections indicating that by 2025, roughly one-third of the global population will grapple with hypertension (5). Despite its pervasive presence in China, the rates of awareness, drug therapy, and effective control of hypertension remain suboptimal, necessitating urgent attention toward early and precise identification of risk factors to preemptively thwart its onset and alleviate the associated burden.

Recent studies have emphasized the importance of prediabetes, characterized by consistently elevated blood glucose levels below the diabetic threshold, in increasing the risk of developing type-2 diabetes and CVD (6, 7). Specifically, a cohort study conducted by Yue et al. (8) in Northeast China, which recruited adults aged 40 and above, demonstrated that individuals in this age group with both hypertension and prediabetes faced a significantly higher risk of CVD mortality compared to those with prediabetes alone. Therefore, identifying individuals with prediabetes who are at a heightened risk of progressing to hypertension is of paramount importance.

Obesity, typified by excessive fat accumulation, has emerged as a strong correlation of hypertension development (9, 10). Amidst China’s rapid economic growth in recent decades, the prevalence of overweight and obesity has surged among adults and adolescents, posing substantial challenges to public health systems (11). Studies have highlighted the association between elevated BP and excessive visceral adipose tissues (VAT), particularly over subcutaneous or total fat (12, 13). However, accurately gauging VAT in large-scale studies poses challenges due to factors like radiation exposure risks, time constraints, and the prohibitive costs linked with gold standard methods such as computed tomography (CT) or magnetic resonance imaging (MRI). Conventional anthropometric measures like body mass index (BMI) and waist circumference (WC) fall short in precisely assessing abdominal fat distribution.

Originally devised based on Caucasian populations, the visceral adiposity index (VAI) has emerged as a dependable proxy for evaluating VAT dysfunction and is significantly tied to an escalated risk of hypertension in Western populations (14, 15). Nevertheless, the utility of VAI in appraising VAT has been found wanting in Asian subjects owing to differing body fat distribution characteristics. The Chinese visceral adiposity index (CVAI), a novel all-encompassing surrogate VAT index tailored for Chinese adults, integrates demographic factors (age), anthropometric metrics (BMI and WC), and lipid profiles (serum triglyceride (TG) and high-density lipoprotein (HDL)) (16). CVAI has exhibited strong alignment with CT validation outcomes and has been linked to a markedly increased risk of CVD (17), hypertension (18), and diabetes (19).

The question remains as to whether CVAI exhibits a positive association with the risk of new-onset hypertension in middle-aged and older adult populations with prediabetes. This study seeks to explore the prospective predictive value of CVAI for new-onset hypertension and assess its efficacy relative to other obesity and insulin resistance-related indices (including triglyceride-glucose index (TyG), TyG-BMI, WC to height ratio (WHtR), BMI and WC) using data from the China Health and Retirement Longitudinal Study (CHARLS).

To the best of our knowledge, this study is the first to investigate the predictive value of CVAI for the development of hypertension in middle-aged and older Chinese individuals with prediabetes. The main findings of this study are as follows: (1) Participants with higher CVAI levels had a significantly increased risk of developing hypertension, even after adjusting for potential confounding factors. (2) There was a linear dose–response relationship between CVAI and the incidence of hypertension. (3) CVAI demonstrated superior predictive ability for new-onset hypertension compared to other indices related to obesity and insulin resistance.

Currently, there exists inconsistency in the diagnostic criteria for prediabetes. The World Health Organization (WHO) defines prediabetes as FPG levels between 6.1 mmol/L and 6.9 mmol/L (110-125 mg/dL) (21). On the other hand, the American Diabetes Association (ADA) recommends a lower cutoff value for FPG (5.6–6.9 mmol/L or 100–125 mg/dL) or hemoglobin A1c (HbA1c) levels of 5.7–6.4% to diagnose prediabetes (20). In this study, we adopted the ADA criteria for prediabetes diagnosis, as previous studies have shown that individuals diagnosed with prediabetes according to ADA criteria have a significantly increased risk of CVD, cardiovascular events, and mortality.

Prediabetes represents a significant risk factor for the development of diabetes, with approximately 5–10% of individuals with prediabetes progressing to diabetes within 1 year, which is significantly higher than the general population’s annual progression rate of around 3.5% (22). In our study, we observed a higher prevalence of prediabetes in rural populations compared to urban individuals (68.02% vs. 31.98%, p < 0.001), which is consistent with a previous cohort study conducted in Northeast China (8).

With the rapid economic and technological development in recent years, obesity, particularly abdominal obesity, has become a significant public health burden in China. An epidemiological study reported an overall obesity rate of 15.76% (BMI ≥28.0 kg/m² for both women and men) and an abdominal obesity rate of 38.65% (WC ≥ 85 cm for women or WC ≥90 cm for men) among middle-aged and older Chinese individuals (23). Visceral obesity, characterized by excessive VAT accumulation, has been found to be strongly associated with an increased risk of cardiovascular disease compared to overall obesity. While WC indeed provides some insights into visceral obesity, its ability to distinguish between subcutaneous and visceral fat levels is limited (24). VAI, initially developed by Amato et al. (14) in Western populations, has been found to be significantly associated with an increased risk of metabolic syndrome (MetS) components, cardiovascular and cerebrovascular events, making it a valuable indicator for assessing visceral obesity function and insulin sensitivity. However, it’s important to note that there are notable variations in body fat percentage and distribution across different racial groups. Asians, in particular, exhibit higher body fat percentage at lower BMI compared to Caucasians and are more prone to accumulating visceral fat (25). Therefore, CVAI, a more comprehensive index, integrating age, HDL, LDL, BMI, and WC, was developed specifically for Chinese populations. In a prospective cohort study involving rural Chinese adults, elevated CVAI levels at baseline and over time were found to be significantly associated with an increased risk of developing hypertension in both males and females. Furthermore, CVAI demonstrated superior predictive capabilities for hypertension compared to other indices of visceral obesity in both genders (26). Cheng et.al (27) also found that CVAI had the best discriminative value for hypertension in patients with type-2 diabetes compared to other abdominal obesity-related indices. Consistent with these findings, our study also revealed a significant association between elevated CVAI levels and an increased risk of developing hypertension in middle-aged and older Chinese individuals with prediabetes. Additionally, CVAI outperformed other obesity and lipid-related indices in identifying individuals at higher risk for developing hypertension.

The detailed mechanisms linking visceral obesity to the development of hypertension in individuals with prediabetes are still not fully understood and warrant further investigation. However, potential explanations include: (1) Upregulated activity of the renin-angiotensin aldosterone system (RAAS) induced by adipose tissue, which may significantly contribute to the development of hypertension in adults with prediabetes. The local RAAS plays a crucial role in adipocyte differentiation and triglyceride modulation (28). Adipocytes secrete Angiotensin II type 2 receptors, which promote the proliferation of mature, insulin-sensitive adipocytes and the differentiation of preadipocytes (29). A prediabetes animal model induced by a high-fat, high-carbohydrate diet showed significantly increased expression of renin, angiotensinogen (AGT), and angiotensin II type 1 receptor (AT1R) in adipose tissue, and importantly, all components of RAAS were significantly increased in the heart in the prediabetes group (30). (2) Insulin resistance, a common pathophysiological process in the development of prediabetes and diabetes, significantly contributes to the pathogenesis of hypertension through various mechanisms in adults with prediabetes, including endothelial dysfunction, sodium retention, heightened sympathetic activity, and vascular hypertrophy (31, 32). An animal study using aged mice found that decreased accumulation of visceral fat was associated with alleviated insulin resistance (33). In our study, we also observed a significant positive correlation between CVAI and TyG-BMI, a well-established surrogate marker of insulin resistance (Pearson analysis: r = 0.70, p < 0.001).

Several limitations should be acknowledged in this study. Firstly, although we observed a significant association between CVAI and the onset of hypertension, the nature of observational study precludes us from establishing a causal relationship. Secondly, the study participants were exclusively Chinese, and therefore, the generalizability of the findings to other ethnic populations, particularly Western adults, warrants further investigation. Thirdly, in this study, we only included adults aged 45 years or older, which restricts the generalizability of our findings to younger populations. Future research should consider including a broader age range of Chinese individuals to assess potential age-related differences in the outcomes. Additionally, the reliance on self-reported data during interviews for the diagnosis of hypertension and diabetes introduces the potential for recall bias. Finally, the recruitment of participants aged 45 and above may limit the broader applicability of the findings, necessitating further large-scale studies involving the general population.

In this study, we found that increased baseline CVAI was positively associated with the risk of developing hypertension, and CVAI may applied as a useful tool for risk stratification of the hypertension incidence in middle-aged and older Chinese adults with a prediabetes stage.