Dietary
antioxidant compounds such as
bioflavonoids may offer some protection against the early stage of
diabetes mellitus and the development of complications. We investigated the effect of citrus
bioflavonoids on
blood glucose level, hepatic
glucose-regulating
enzymes activities,
hepatic glycogen concentration, and plasma
insulin levels, and assessed the relations between plasma
leptin and
body weight,
blood glucose, and plasma
insulin. Male C57BL/KsJ-db/db mice (db/db mice, 5 wk old), an animal model for
type 2 diabetes, were fed a nonpurified diet for 2 wk and then were fed an AIN-76 control diet or the control diet supplemented with
hesperidin (0.2 g/kg diet) or
naringin (0.2 g/kg diet).
Hesperidin and
naringin supplementation significantly reduced
blood glucose compared with the control group. Hepatic
glucokinase activity and
glycogen concentration were both significantly elevated in the
hesperidin- and the
naringin-supplemented groups compared with the control group.
Naringin also markedly lowered the activity of hepatic
glucose-6-phosphatase and
phosphoenolpyruvate carboxykinase compared with the control group. Plasma
insulin,
C-peptide, and
leptin levels in the db/db mice from the 2
bioflavonoid-supplemented groups were significantly higher than those of the control group. Furthermore, plasma
leptin was positively correlated with plasma
insulin level (r = 0.578, P < 0.01) and
body weight (r = 0.541, P < 0.05), and was inversely correlated with the
blood glucose level (r = -0.46, P < 0.05). The current results suggest that
hesperidin and
naringin both play important roles in preventing the progression of
hyperglycemia, partly by increasing hepatic glycolysis and
glycogen concentration and/or by lowering hepatic gluconeogenesis.