Leptin, a hormone produced by fat cells, is crucial for regulating energy equilibrium, managing body mass, and influencing metabolic and cardiovascular well-being. Leptin decreases appetite, boosts energy usage, and has a significant impact on glucose metabolism by primarily activating the JAK2/STAT3 signaling pathway in the hypothalamus. Obesity leads to the development of leptin resistance, which is marked by high levels of leptin in the bloodstream and a decreased responsiveness to its signals. This leads to increased food consumption, weight gain, and metabolic issues, such as type 2 diabetes (T2DM) and cardiovascular disease (CVD). This study explores the many roles of leptin in metabolic regulation, with a specific emphasis on its interaction with insulin and its impact on peripheral organs like the pancreas, liver, and muscles. Leptin resistance worsens chronic inflammation, oxidative stress, endothelial dysfunction, and insulin resistance, all of which are strongly linked to the development of cardiovascular disease (CVD). Moreover, there is a correlation between genetic variations in the leptin receptor (LEPR) gene and a higher susceptibility to stroke and other cardiovascular issues. Therapeutic interventions, such as leptin replacement therapy, have demonstrated potential in the treatment of congenital leptin insufficiency and lipodystrophy while also enhancing glycaemic control, lipid profiles, and neuroendocrine function. Recent studies have indicated that manipulating leptin levels or enhancing its responsiveness by specific treatments, such as chemical chaperones and inhibitors of negative regulators like SOCS3 and PTP1B, might potentially restore the efficacy of leptin.