Effects of carob (Ceratonia siliqua) and carob-derived products on glycaemic control and insulin resistance: a systematic review of clinical trials

Abstract

Carob (Ceratonia siliqua L.) is a traditional Mediterranean ingredient rich in dietary fibre, polyphenols, and inositols that is increasingly incorporated into modern foods. However, clinical evidence regarding its effects on glycaemic control and insulin resistance remains fragmented. This systematic review synthesised evidence from randomised and controlled human clinical trials evaluating the effects of carob and carob-derived products on postprandial and fasting glycaemic outcomes, as well as insulin resistance markers, across different metabolic phenotypes. PubMed, Scopus, the Cochrane Library, and Web of Science were searched from inception to the final search date following PRISMA 2020 guidelines and PROSPERO registration (CRD420251241518). Fifteen clinical trials conducted in healthy adults, individuals with prediabetes or insulin resistance, and patients with type 2 diabetes were included. In healthy subjects, carob-containing solid foods generally elicited low to moderate postprandial glycaemic responses compared with conventional carbohydrate controls, whereas isolated carob powder or fibre administered in liquid form showed weaker or more variable effects. In metabolically compromised populations, carob-pod-derived inositol-enriched preparations and selected carob-based functional foods were associated with modest improvements in insulin resistance indices, although intervention duration and background dietary changes may influence effect magnitude. Evidence in established type 2 diabetes was limited and frequently confounded by multi-component interventions. Overall, selected carob-containing foods may contribute to lower postprandial glycaemic responses, whereas carob-specific insulin-sensitising effects remain preliminary. Longer, adequately powered trials with standardised comparators and clinically meaningful endpoints, particularly glycated haemoglobin, are required to clarify its role in glycaemic management.