Insomnia Modifies the Association Between Insulin Resistance and Incident Hypertension in Hispanic/Latino Adults: A 6-Year Longitudinal Study

Purpose: We aimed to explore whether insomnia modifies the relationship between insulin resistance (IR) and incident hypertension (HTN) over a 6-year longitudinal period. Methods: To explore the longitudinal relationship between IR, insomnia, and HTN, we included data from 3300 participants over a 6-year follow-up period in a large Hispanic/Latino cohort. IR was defined using the Youden index to select the optimal homeostasis model assessment of insulin resistance cut‑point based on ROC curve analysis, while insomnia was assessed using the Women’s Health Initiative Insomnia Rating Scale. Cox regression analysis was performed to assess the relationship between IR, insomnia and incident HTN. Results: We found neither IR nor insomnia alone was associated with incident HTN, whereas IR combined with insomnia increased the risk of HTN by 39% (HR, 1.39; 95% CI, 1.05– 1.85) after adjustment for potential confounders. Meanwhile, a significant interaction between IR and insomnia was observed (P = 0.045). Post-estimation linear combination analyses showed that IR was associated with a 60% higher risk of incident HTN among participants with insomnia (HR, 1.60; 95% CI, 1.16– 2.21), but not among those without insomnia. Moreover, this synergistic association was significantly associated with incident HTN among men and participants younger than 42 years. Conclusion: This large, longitudinal study identified a significant longitudinal relationship that IR was associated with a higher HTN risk only among participants with insomnia, suggesting that coexisting insomnia may identify a subgroup particularly susceptible to hypertension. Plain Language Summary: Insulin resistance occurs when the body does not respond effectively to insulin and may increase the likelihood of developing high blood pressure. Insomnia has also been linked to cardiovascular and metabolic problems, but it remains unclear whether insomnia makes people with insulin resistance more susceptible to hypertension. We analyzed data from 3,300 Hispanic and Latino adults who were followed for approximately 6 years. Insulin resistance alone was not associated with a significantly higher risk of hypertension. However, among participants with insomnia, insulin resistance was associated with a 60% higher risk of developing hypertension. These findings suggest that people with both insulin resistance and insomnia may represent a subgroup at increased risk of hypertension. Further studies are needed to confirm these findings and determine whether improving sleep can help reduce this risk.