Can Green Tea Be Beneficial to Blood Glucose Control?


Glycemic Control is a daily struggle for Type 1 Diabetics. However, now with Type 2 Diabetes on the increase, due to our obese population something has to be done about our wayward glucose levels before they cause too much harm?

Glycemic control doesn’t only happen in diabetics but in all of us. It is constantly working as we digest and as we rest. Glycemic control mechanisms maintain our blood sugar between two narrow limits. As soon as we eat a meal the mechanism is kicked into action. This prevents our blood sugars from soaring too high (hyperglycaemia) our plummeting too low (hypoglycaemia).

How is glucose absorbed and how does the body react to Glucose?

Glucose is a form of simple sugar. Glucose in its purest form comes from the breakdown of starch. Foods rich in this are foods such as bread, pasta, rice and potatoes. Glucose is then partially broken-down in the mouth, then broken down in full within the stomach and small intestine. Glucose will the enter the blood stream and travel to active cells to be used as energy, or go into storage.

Naturally, when we eat our blood glucose levels increase. It is the role of the pancreas to oversee the blood glucose level. It does so because it has a very good blood supply, even the slightest change can spark the pancreas into action. The Pancreas houses a group of cells called the Islets of Langerhans, which contains an alpha and a beta cell type. The alpha cells produce the hormone glucagon. The Beta cells produce the hormone Insulin. So, when food is consumed and blood glucose levels are up the beta cells are stimulated to release Insulin. Insulin encourages the GLUT4 transporter (Glucose Transporter Type 4) to move to surface of the cell and present itself so that glucose can be taken into the cell. This is an example of facilitated diffusion. The transporter attaches then engulfs glucose into the cell. These types of transporters are predominantly found in muscle, fat and cardiac cells. When Glucose is taken up it can be stored as glycogen. This can be released if and when the body’s glucose levels drop or when more energy is required [1].

The best way to test glycemic control is is by measuring the HbA1c, which is the volume of glycated haemoglobin. This simply describes the number of red blood cell haemoglobin carrying a glucose molecule. The higher the number, the greater the risk or severity of diabetes related side effects. The HbA1c is indicative of how much glucose in the overall system, particularly over a substantial amount of time. Our red blood cells regenerate approximately every 8-12 weeks, so it can demonstrate on average how well our body is able to cope with this. A normal value for this is 6% glycated haemoglobin, anything over 6.5% demonstrates a greater problem, such as poor glycemic control and diabetes [2].

What Problems can Occur as Result of Poor Glycemic Control?

  • Hypertension
  • A Microvascular complication, burst blood vessels, constipation, a decline in eyesight.
  • Tachycardia (increased heart rate)
  • Macrovascular problems, coronary heart disease or Ischemia (loss of blood flow).
  • Reduced Cognitive function [3].

What is the best way to encourage Glycemic control?

There are a number of methods that are used to regulate glycemic control, this can include losing weight, increasing activity, controlling dietary intake of simple sugars and taking supplements. The most effective supplements that help to control blood glucose include Cinnamon, Aloe Vera Garlic, White kidney bean, Chromium and Green Tea.

Green tea and Glycemic Control.

Green Tea is a popular herbal and fragrant beverage mainly associated with Asian cultures. It is a leaf extract of the Camellia Sinensis or Assam Tea Plant. It is the potent natural compounds of this plant that lends its self to the celebrated as the therapeutic health drink that it is today.

The active ingredients of Green Tea are polyphenols such a catechins and epigallocatechin gallate (EGCG). They have had extensive effects in aiding Alzheimer's, Hypertenisve and Cancer patients recover, but recent developments have shown the effect that EGCG can have an effect on diabetics and people with poor glycemic control. Some studies have shown that EGCG may mimic the role of Insulin. Thus, encouraging a reduction in blood glucose for utilisation within the cell or for storage. By mimicing Insulin it also prevents the liver and muscle cells from reacting to glucagon and releasing their storage from of glucose (glycogen) into the blood stream [4].

Current Studies have shown that Green Tea can have great effect on not only lowering small fluctuations of blood glucose but also long term HbA1c. Increasing long term glycemic control can help prevent the disastrous effects of poor blood glucose control [5]. As a result there was a 0.09mmol/L decrease in fasting blood glucose level and 0.3% decrease in HbA1c concentration [6].

We recommend consuming all your meals within green tea. This will help the body to metabolise glucose in a steady and controlled manner and will help to moderate the large blood glucose fluctuations generated[7].

  1. Huang. S. (2007). Shaohui Huang, Michael P. CzechcorrespondencePress enter key for correspondence informationemailPress enter key to Email the author Open Archive DOI: show. Cell metabolism. 5 (4), Pg. 237-252.
  2. Diabetes UK. (2016). Guide to HbA1c. Available:
  3. Johnson. T. (2006). Comorbidities and Complications of Poor Glycemic Control. Univerisity of Tennessee Advanced Studies in Pharmacy. 3 (6), Pg. 212-219.
  4. Pacific College of Oriental Medicine . (2016). Green Tea Lowers the Blood Sugar Level. Available:
  5. Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-. Effect of green tea on glucose control and insulin sensitivity: a meta-analysis of 17 randomized controlled trials. 2013. Available from:
  6. Daniells.S. (2013). Green Tea Shows Benefits for Blood Sugar Management: Meta-analysis. Available:
  7. J. Josic, A.T. Olsson, J. Wickeberg, S. Lindstedt, J. Hlebowicz. “Does green tea affect postprandial glucose, insulinand satiety in healthy subjects: a randomized controlled trial” Nutrition Journal Volume 9, Issue 63, doi: 10.1186/1475-2891-9-63

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