Additive Effects of Quercetin-Rich Allium cepa L. Juice and Dapagliflozin on Glycemic Variability in Streptozotocin-Induced Diabetic Rats

Glycemic variability is a stand-alone risk factor for diabetic complications. Background/Objectives: We investigated whether combining quercetin-rich Allium cepa L. (white onion) juice with the sodium-glucose cotransporter-2 (SGLT2) inhibitor dapagliflozin could reduce glycemic variability beyond that achieved with monotherapy in experimental diabetes.

Methods

Wistar rats were made diabetic with streptozotocin (35 mg/kg) and maintained for 60 days in the following groups: vehicle, dapagliflozin (0.1 mg/day), fresh onion juice (5 mL twice daily), and dapagliflozin + fresh onion juice (5 mL twice daily). Diabetic Wistar rats (n = 10/group) were gavaged with vehicle, dapagliflozin (0.1 mg/day), fresh onion juice (5 mL twice daily), or both. The juice was expected to contain phytochemicals (quercetin derivatives and organosulfur compounds) based on published reports on similar A. cepa cultivars. A validated immunoassay was used to measure glycated hemoglobin (HbA1c) every 10 days. All treatments reduced HbA1c to the same level (~7.1–7.2%) as compared to diabetic controls (9.0 ± 0.3%) (p p Results: Across the 10-day sampling schedule, the combination kept HbA1c within a narrow 6.8–7.2% band, whereas the monotherapies fluctuated more widely; because intraday and postprandial glucose were not captured, effects on short-term excursions could not be directly assessed. There were no cases of severe hypoglycemia and only infrequent and non-repeated cases of mild hypoglycemia.