Glycemic and cardiometabolic effects of rare sugars allulose and tagatose: a systematic review and meta-analysis of controlled human intervention trials

BACKGROUND: Allulose and tagatose are rare monosaccharides gaining attention as potential alternatives to added sugars. OBJECTIVES: This systematic review and meta-analysis aimed to evaluate the effects of allulose and tagatose supplementation on glycemic, cardiometabolic, and anthropometric outcomes in adults. METHODS: The Medline, Embase, and Cochrane libraries were searched through 30 April, 2025, for controlled human intervention trials reporting the effects of tagatose or allulose on postprandial and fasting glucose and insulin concentrations, blood lipids, uric acid, and anthropometric measures of adiposity in adults. Meta-analyses were conducted using mean differences (MDs) with random-effects models applied to all analyses. The risk of bias was evaluated using the Cochrane Risk of Bias 2 and Risk of Bias In Nonrandomized Studies-Interventions tools, and the certainty of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation approach. RESULTS: = 96%; P = 0.03; moderate certainty], with no significant effects on glycated hemoglobin (HbA1c), fasting glucose or insulin, lipids, uric acid, or body composition (very low to moderate certainty). Tagatose intake similarly lowered postprandial glucose [SMD = -1.03 (-1.36, -0.71)] and insulin [SMD = -1.05 (-1.61, -0.49); both moderate certainty] and also reduced HbA1c [MD = -0.25 (-0.44, -0.06); moderate certainty] and fasting insulin [MD = -80.40 (-136.96, -23.84); very low certainty]. No other significant pooled effects were observed. CONCLUSIONS: Supplementation of allulose or tagatose attenuates postprandial glycemic and insulin responses, albeit with no improvements in blood lipids and body composition. This trial was registered at PROSPERO as CRD42024567433.