The world witnesses an
explosive increase in diabetes, demanding intensified prevention and treatment not least for the low-income population. The plant, Stevia rebaudiana Bertoni, has been used for the treatment of diabetes in
traditional medicine. We have previously demonstrated that
stevioside, a
diterpene glycoside isolated from the plant Stevia rebaudiana Bertoni, possesses insulinotropic, glucagonostatic,
antihyperglycemic, and blood pressure-lowering effects in animal studies. We have also found that a dietary supplement, Abalon, of
soy protein,
isoflavones, and cotyledon fiber has beneficial effects on cardiovascular risk markers in
type 2 diabetes. The aim of this study was to investigate if the combination of
stevioside and a dietary supplement of
soy protein possesses beneficial qualities in the treatment of
type 2 diabetes and the
metabolic syndrome. We randomized male Zucker diabetic fatty rats into 4 groups and fed them the different test diets for 10 weeks: (A) standard
carbohydrate-rich laboratory diet (chow), (B) chow+stevioside (0.03 g/kg
body weight [BW] per day), (C) 50% soy (Abalon)+50% chow (adjusted for
vitamins and minerals), and (D) 50% soy (Abalon)+50% chow+stevioside 0.03 g/kg BW per day. We measured plasma
glucose, blood pressure, weight, and food intake once weekly. The animals were equipped with an intra-arterial
catheter, and at week 10, the conscious rats underwent an intra-arterial
glucose tolerance test (2.0 g/kg BW).
Stevioside exerts beneficial effects in type 2 diabetic Zucker diabetic fatty rats, that is, lowers
blood glucose (area under the
glucose curve [AUC(30min)]: group A vs B,
a 19% reduction; and group C vs D, a 12% reduction; P<.001). We did not detect any effect on
insulin or
glucagon responses. After 2 weeks of treatment, a decrease in the systolic blood pressure was observed in the
stevioside-treated groups (P<.01). Abalon had beneficial effects on cardiovascular risk markers, that is, (1) lowers total
cholesterol (P<.01), (2) reduces
triglycerides (P=.01), and (3) reduces
free fatty acids (P<.001). The combination of
stevioside and soy supplementation appears to possess the potential as effective treatment of a number of the characteristic features of the
metabolic syndrome, that is,
hyperglycemia,
hypertension, and
dyslipidemia. A long-term human study of the concept in type 2 diabetic subjects is needed to verify these promising results in animal diabetes.