Plant derived compounds, e.g. flavonoids from dark chocolate, green tea, or blueberries, show great potential as nutraceuticals for the treatment of various diseases such as type 2 diabetes (T2D). Flavonoids have been suggested to improve glucose metabolism, reduce blood lipids, reduce oxidative stress and improve vascular function. For these reasons we recently investigated the effects of daily consumption of locally produced blueberry tea and demonstrated that this could partially restore insulin sensitivity in an animal model. We propose to translate these findings to assess the efficacy of this nutraceutical as a new treatment for improving glucose tolerance in people with T2D.
Current treatments for T2D are limited, have unwanted side effects, and lose effectiveness over time. There is a growing public interest in the use of complementary and alternative approaches for treating insulin resistance and T2D. Blueberries, blueberry leaves and cinnamon have each been reported to improve insulin sensitivity or insulin action. Blueberry Boost™ is a locally produced Blueberry Tea and is a proprietary blend of dried blueberries (37% wt/wt), blueberry leaves, raspberry leaves, spearmint leaves and cinnamon. It is well established that improving glycemic control is important for managing insulin resistance and T2D and the associated vascular pathologies that directly contribute to end-organ damage (microvascular disease), hypertension and cardiovascular disease (stroke, heart attack and heart failure). We have recently demonstrated that a unique blueberry tea blend fully restores the vascular insulin sensitivity in muscle of the high-fat fed insulin-resistant rat model and is associated with substantial improvements in muscle glucose uptake and whole body insulin sensitivity. We propose to translate these findings to assess the efficacy of this nutraceutical as a new treatment for improving glucose tolerance in people with T2D. Aim: Determine whether chronic consumption (4 weeks) of blueberry tea can improve metabolic and vascular health in people with and without T2D.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
36
Blueberry Tea
Menzies Institute for Medical Research
Hobart, Tasmania, Australia
RECRUITINGImprovement in Glucose Tolerance after 4 weeks of drinking blueberry tea.
Oral glucose tolerance test (75g glucose) measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design). Blood glucose and plasma insulin levels measured at 0, 15, 30, 60, 90 and 120 min following consumption of glucose load.
Time frame: 4 weeks
Improvement in Hemoglobin A1c (HbA1c) levels after 4 weeks of drinking blueberry tea.
HbA1c levels measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks.
Improvement in fasting Serum Lipid (cholesterol, HDL, LDL,triglycerides) levels after 4 weeks of drinking blueberry tea.
Fasting serum lipids (cholesterol, HDL, LDL,triglycerides) measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks
Improvement in fasting serum pro-inflammatory cytokine (IL-6, IL-1b, CRP, TNFa) levels after 4 weeks of drinking blueberry tea.
Fasting serum pro-inflammatory cytokines (IL-6, IL-1b, CRP, TNFa) assessed by ELISA will be measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks
Improvement in fasting serum albumin levels after 4 weeks of drinking blueberry tea..
Fasting serum albumin levels measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks
Fasting serum electrolytes (Na, K, Cl, HCO3).
Fasting serum electrolytes (Na, K, Cl, HCO3) measured on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks
Improvement in Resting Blood Pressure (central and brachial blood pressure) after 4 weeks of drinking blueberry tea.
Blood Pressure (central and brachial blood pressure) will be measured by Mobil-O-Graph and assessed on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks
Improvement in resting Augmentation Index after 4 weeks of drinking blueberry tea.
Augmentation index will be measured by Mobil-O-Graph and assessed on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks
Improvement in large artery stiffness after 4 weeks of drinking blueberry tea.
Large artery stiffness will be measured by Mobil-O-Graph and assessed on 3 occasions: at baseline, after 4 weeks of drinking blueberry tea, and after 4 weeks of no treatment (randomized cross-over design).
Time frame: 4 weeks
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