Impact of Non-Pharmacological Complementary Therapies on Glycemic Control in Prediabetic Adults

Background: Prediabetes is a reversible metabolic condition characterized by disrupted glucose regulation and an increased risk of developing type 2 diabetes mellitus and cardiovascular disease. Complementary or non-pharmacological therapies, such as lifestyle changes, exercise, mind–body interventions, dietary modifications and nutraceutical supplementation, are increasingly recognized as preventive strategies. The aim of this systematic review was to determine the effects of these therapies on glycemic control in adults with prediabetes. Methods: The review was conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and registered in PROSPERO (CRD420261291327). The databases searched included MEDLINE, PubMed, Scopus, and the Science Citation Index. Eligible studies were interventional studies published in English between January 2010 and January 2025. Both non-randomized interventions and randomized controlled trials involving adults with prediabetes were included. Glycemic parameters, including HbA1c, fasting plasma glucose, and glucose tolerance, were the primary outcomes. The Cochrane Risk of Bias Tool and Grading of Recommendations Assessment, Development and Evaluation were used to assess methodological quality. Results: A total of 11 studies were included after screening 910 records. Lifestyle interventions (dietary modification, exercise, and behavioral modification) demonstrated the most consistent improvements in glycemic control, body weight, and metabolic risk factors, with some participants achieving normoglycemia. Exercise and mind–body approaches improved insulin sensitivity and cardiometabolic health. Nutraceuticals demonstrated limited effects, whereas digital and sleep-based interventions showed emerging potential. Conclusion: Non-pharmacological complementary therapies are effective in improving glycemic control in individuals with prediabetes, particularly when delivered as integrated lifestyle programs. Greater emphasis should be placed on multicomponent behavioral interventions as a diabetes prevention tool; however, additional large-scale studies with long-term follow-up are required to determine the sustainability of these benefits.