Carob (Ceratonia siliqua L.) in Glucose Homeostasis and Energy Balance: The Role of D-Pinitol

The global rise in obesity and metabolic disorders has intensified interest in dietary bioactives capable of improving glycemic control and metabolic health. Inositols, particularly D-pinitol, have emerged as insulin-sensitizing cyclitols with potential metabolic relevance. Carob (Ceratonia siliqua L.), one of the richest natural sources of D-pinitol, represents a promising nutritional matrix for metabolic regulation. This narrative review critically evaluates current evidence on the role of D-pinitol in glucose homeostasis and energy balance, integrating data from chemical characterization studies, mechanistic research, preclinical models, and human clinical trials assessing purified D-pinitol and D-pinitol–rich preparations, particularly from carob-derived sources. Available evidence suggests that D-pinitol may enhance insulin signaling efficiency, primarily through PI3K/Akt-dependent pathways, modulate hepatic metabolic flexibility, and influence endocrine balance without acting as a classical hypoglycemic agent. Preclinical models consistently report improvements in insulin sensitivity, lipid handling, oxidative stress parameters, and tissue-specific metabolic adaptations. In contrast, clinical trials in healthy, prediabetic, and type 2 diabetic individuals show more heterogeneous outcomes, including attenuation of postprandial glycemia, reductions in circulating insulin and HOMA-IR, and modest improvements in lipid and inflammatory markers. Overall, carob-derived D-pinitol appears to act as a potential insulin-sensitizing metabolic modulator with context-dependent effects influenced by metabolic phenotype and food matrix composition. However, available data remains limited and heterogeneous, with most data derived from preclinical studies and relatively small clinical trials. These findings should therefore be interpreted with caution. Larger, longer-term randomized controlled trials using standardized preparations are required to establish clinical relevance and translational applicability. Notably, the contribution of other bioactive components within the carob matrix cannot be excluded.