Combined myo-inositol and Banaba (1% Corosolic Acid) improve HOMA-IR and hepatic insulin extraction index in overweight and obese postmenopausal women

Objective: To assess the effects of a 12-week combined treatment with myo-inositol (2 g) and Banaba extract (48 mg) standardized to 1% corosolic acid (MBN) on insulin resistance (HOMA-IR) and hepatic insulin extraction index (HIEI) in overweight and obese postmenopausal women. Methods: We conducted a retrospective observational study including 31 postmenopausal women (mean age 51 ± 1.2 years) attending the Gynecological Endocrinology Center of Modena, Italy. All patients received daily supplementation with MBN for 12 weeks. Hormonal and metabolic parameters—including fasting glucose, insulin, C-peptide, and HOMA-IR—were assessed before and after treatment. In addition, an oral glucose tolerance test (OGTT) was performed at both time points, with glucose, insulin, and C-peptide curves measured and corresponding area under the curve (AUC) values at 240 minutes calculated. HIEI was calculated as the insulin/C-peptide ratio. Data were analyzed globally and then stratified by family history of diabetes. Results: After treatment, fasting insulin, HOMA-IR, and HIEI were significantly reduced. The OGTT showed a 23.5% decrease in glucose AUC, with greater reductions in insulin AUC (−42%) compared to C-peptide AUC (−16.8%), suggesting enhanced hepatic insulin clearance. Patients with a family history of diabetes showed reductions in insulin and C-peptide, while those without showed only a decrease in insulin and HIE, with no changes in C-peptide. Conclusions: Combined MBN supplementation improved insulin sensitivity and hepatic insulin clearance in overweight and obese postmenopausal women, with particularly pronounced effects in those with a family history of diabetes. These findings underscore the potential of targeted integrative strategies to mitigate insulin resistance in this population.