The Benefits of Non-Pharmaceutic Interventions on Intrinsic Capacity in Insulin-Resistant Adult and Geriatric Populations—A Narrative Review

Insulin resistance (IR) is a well-established metabolic disorder characterized by reduced responsiveness of peripheral tissues to insulin, leading to hyperglycemia and compensatory hyperinsulinemia. Background: In older adults, IR tends to develop gradually and may remain undiagnosed for years due to the insidious nature of the condition, which often lacks overt symptoms. Non-pharmacological interventions refer to the sum of all measures taken in order to improve a certain biological determination or physical parameter and they consist of lifestyle and dietary modifications. Although insulin resistance is recognized as a central mechanism involved in the development of numerous chronic diseases associated with aging, its impact on intrinsic capacity and the mechanisms underlying this relationship are insufficiently synthesized in the literature. In this context, the present narrative review aims to integrate the current evidence on the interaction between insulin resistance and intrinsic capacity, highlighting common biological mechanisms and potential therapeutic and preventive strategies to promote healthy aging. Methods: We conducted a literature search in PubMed, Scopus and Web of Science databases, screening the literature published between 2010 and January 2026. The search strategy included keywords and Boolean operators in order to refine the suggestions. Relevant articles, reviews, studies and guidelines were selected based on their relevance to the objective of this review. Results and Conclusions: The results of the review highlight that insulin resistance represents a central mechanism contributing to the decline in intrinsic capacity through chronic inflammation, oxidative stress, mitochondrial dysfunction and alteration of the gut microbiota. Current evidence suggests that nutritional interventions, in particular the Mediterranean diet and the DASH diet, can improve insulin sensitivity by modulating the microbiota and reducing systemic inflammation, with the potential to contribute to maintaining functional capacity and promoting healthy aging.