The Role and Potential Therapeutic Implications of the Fibroblast Growth Factors in Energy Balance and Type 2 Diabetes

Purpose of Review Obesity and its associated metabolic diseases have reached epidemic proportions worldwide, reducing life expectancy and quality of life. Several drugs have been tested to treat these diseases but many of them have damaging side effects. Consequently, there is an urgent need to develop more effective therapies. Recently, endocrine fibroblast growth factors (FGFs) have become attractive targets in the treatment of metabolic diseases. This review summarizes their most important functions as well as FGF-based therapies for the treatment of obesity and type 2 diabetes (T2D). Recent Findings Recent studies demonstrate that circulating levels of FGF19 are reduced in obesity. In fact, exogenous FGF19 administration is associated with a reduction in food intake as well as with improvements in glycaemia. In contrast, FGF21 levels are elevated in subjects with abdominal obesity, insulin resistance and T2D, probably representing a compensatory response. Additionally, elevated levels of circulating FGF23 in individuals with obesity and T2D are reported in most clinical studies. Finally, increased FGF1 levels in obese patients associated with adipogenesis have been described. Summary FGFs constitute important molecules in the treatment of metabolic diseases due to their beneficial effects on glucose and lipid metabolism. Among all members, FGF19 and FGF21 have demonstrated the ability to improve glucose, lipid and energy homeostasis, along with FGF1, which was recently discovered to have beneficial effects on metabolic homeostasis. Additionally, FGF23 may also play a role in insulin resistance or energy homeostasis beyond mineral metabolism control. These results highlight the relevant use of FGFs as potential biomarkers for the early diagnosis of metabolic diseases. In this regard, notable progress has been made in the development of FGF-based therapies and different approaches are being tested in different clinical trials. However, further studies are needed to determine their potential therapeutic use in the treatment of obesity and obesity-related comorbidities.