Insulin resistance and impaired glucose regulation are major contributors to the development of type 2 diabetes mellitus (T2DM). Inositol, a naturally occurring carbocyclic sugar, has shown as a low-risk intervention to improve metabolic outcomes. Although its efficacy in managing polycystic ovary syndrome (PCOS) is well established, its metabolic applications remain unclear.This systematic review aimed to evaluate the effects of inositol supplementation in adults with various metabolic risk factors.A systematic search of PubMed was conducted to identify studies published between January 2015 and May 2025 that investigated the effects of myo-inositol or D-chiro-inositol supplementation in adults with metabolic risk factors. Eligible studies were limited to human and English trials with outcomes related to glycemic parameters. Studies exclusively focused on PCOS or lacking relevant metabolic endpoints were excluded. The primary outcome was change in insulin resistance, assessed by the homeostasis model assessment of insulin resistance (HOMA-IR). Secondary outcomes included fasting plasma glucose (FPG), oral glucose tolerance test (OGTT) results, incidence of gestational diabetes mellitus (GDM), and adverse effects. Key study characteristics and metabolic outcomes were extracted and synthesized descriptively.A total of twelve studies were included. Most trials reported significant reductions in HOMA-IR following myo-inositol supplementation, either alone or in combination with other agents. Improvements were also observed in glycemic markers such as fasting glucose and OGTT results. Four out of five studies reported significantly lower GDM incidence in intervention groups. No serious adverse events were reported.Inositol supplementation appears to be a safe and effective for improving insulin resistance, as evidenced by consistent reductions in HOMA-IR across diverse at-risk populations. The observed improvements in secondary glycemic outcomes and the low incidence of adverse effects further suggest its potential role as an adjunctive therapy for early metabolic risk management. However, variations in study design and participant characteristics highlight the need for more standardized research protocols.Current evidence supports inositol supplementation as a promising adjunctive intervention to enhance insulin sensitivity and metabolic outcome. Future studies should determine the optimal dosage, timing, and target populations—particularly among individuals with prediabetes—to facilitate its integration into routine metabolic care.